WEPL
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Wednesday Poster Session: WEPL
10 May 2023, 16:30 -
18:30
WEPL001
Progress on the 6BA lattice for ALBA-II
3098
The ALBA-II upgrade lattice to a diffraction limited soft X-rays storage ring calls for an emittance smaller than 200 pm*rad in a 269 m circumference at an energy of 3 GeV. In this paper we report on progress of the 6BA lattice with distributed chromatic correction. This lattice relies on transverse gradient dipoles and reverse bends to suppress the emittance. Several modifications to the lattice presented in 2021 have been introduced in order to easy the injection with high horizontal beta function and a longer section for the septum, to make more efficient the chromaticity correction with the sextupoles, and to provide room for the orbit correctors. The last performances of the linear and non-linear beam dynamics are presented in this paper.
Paper: WEPL001
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL001
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL002
ALBA beam lifetime optimization using RCDS
3101
The ALBA synchotron operates in a Touschek dominated lifetime regime, which depends mainly on the momentum acceptance and the transverse beam size along the machine. Although in the current ALBA machine the RF dominates the momentum acceptance, this will not be the case for the foreseen upgrade of the machine ALBA-II. For this reason, we have developed an algorithm to optimize the beam lifetime by varying the sextupole magnets. This algorithm is based on the Powell optimization of the Robust Conjugate Direct Search (RCDS) method, and several tests have been performed at the present ALBA machine. In this case the sextupole settings are first modified so that the RF is no longer the only limiting factor in the momentum acceptance. The algorithm optimizes the ALBA beam lifetime by varying the sextupoles to follow a constant chromaticity, while the skew magnets are tweaked to keep the beam sizes constant during the optimization. This paper shows the experimental results using this algorithm, and discusses its application to the ALBA-II case.
Paper: WEPL002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL002
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
WEPL003
ALBA-II first tolerance studies
3104
While the design of the ALBA-II is in progress, it is required to assess the consequences of realistic imperfections such as alignment tolerances and magnetic errors. Compensation of insertion device induced optics variation has been studied, as well as the small impact on the emittance due the introduction of 3 T superbends. We demonstrate that non-linear optics is rather robust in the presence of realistic imperfections, rendering a ±6 mm dynamic aperture sufficient for off-axis injection and a large momentum acceptance that supplies more than 5 hour lifetime including errors. Moreover, studies in preceding low emittance light sources required simulating the full accelerator tuning, starting from the commissioning phase. To this end, the Simulated Commissioning (SC) toolbox has been used intensively. Specific set of tests have been developed to complement the SC simulations including lifetime and dynamical aperture calculations assuming a possible operation in full coupling.
Paper: WEPL003
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL003
About: Received: 02 May 2023 — Revised: 08 Aug 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL004
Differentiable beam optics optimization and measurement
3108
Particle accelerators require extensive optics measurement and correction. Due to the complexity of analytic treatments, numerical optimizations are often employed. A disadvantage of this approach is the lack of gradients, limiting optimization methods to derivative-free ones such as simplex or genetic algorithms. We explore a reformulation of beam optics that preserves gradient information by making use of efficient automatic differentiation tools from machine learning frameworks. First, standard beam dynamics computations are converted to a graph of operations on tensors that calculates objectives. Backpropagation is then performed to find parameter gradients and higher order derivatives. Using gradient-aware optimizer algorithms, we showed improved performance in beamline optics matching over existing tools. We also demonstrated an important use of differentiable models in Bayesian inference, whereby probabilistic estimates of magnet parameters and linear optics functions can be obtained from experimental measurements. Our results on test problems showed robust performance and estimates in agreement with standard LOCO methods.
Paper: WEPL004
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL004
About: Received: 05 May 2023 — Revised: 18 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL006
Improvements to the commissioning simulations of the APS Upgrade storage ring
3112
The commissioning of the APS Upgrade storage ring will need to be completed fast in order to minimize the dark time for APS users. To help speed up commissioning, lattice commissioning simulations were developed that allow to test commissioning algorithms and automate the entire process. In this paper, we describe recent improvements and additions to the commissioning simulations. We cover the addition of the transfer line commissioning, handling of larger than expected errors, use of survey results in the first-turn trajectory correction, and discuss lattice correction results.
Paper: WEPL006
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL006
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL007
Measurement and simulations of the energy variation-induced orbit motion in a low momentum compaction APS lattice
3116
The APS Upgrade storage ring will keep the same rf system that is currently used at APS. This rf system has amplitude and phase noise dominated by the lines at 60, 180, and 360 Hz. APS presently operates with a synchrotron frequency close to 2 kHz, which is far away from the rf noise frequencies, but APS-U will operate with a bunch-lengthening cavity, which could lower the synchrotron frequency down to the range between 100 to 500 Hz depending on the cavity setup. Such low synchrotron frequency could lead to resonant amplification of the energy variation-induced orbit motion. In this paper, we describe measurements of the orbit motion at APS in a specifically designed low momentum compaction lattice that allowed us to lower synchrotron frequency below 300 Hz. We also show good agreement with our simulations.
Paper: WEPL007
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL007
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL008
Nonlinear optics from hybrid dispersive orbits
3119
We expanded the capability of the nonlinear optics from off-energy closed orbits technique proposed by Olsson et al. to include harmonic sextupole correction in storage rings. The existing technique was successfully used to correct the errors of chromatic sextupoles on the MAX-IV machine. However, it was not applicable to harmonic sextupoles, which are widely used in $3^{rd}$-generation light sources, and even some $4^{th}$-generation diffraction-limited machines. By introducing vertically dispersive orbits with skew quadrupoles, we were able to observe a measurable dependency on harmonic sextupoles. We used both simulations and beam measurements at the National Synchrotron Light Source II storage ring to demonstrate the expanded capability of our technique.
Paper: WEPL008
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL008
About: Received: 30 Mar 2023 — Revised: 11 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL009
Linear optics compensation for the HEX superconducting wiggler at NSLS-II
3123
At the NSLS-II ring, a 1.2 m long superconducting wig- gler with the maximum 4.34T magnetic field has been in- stalled at a low-β straight section (cell 27) to drive the high energy engineering X-ray scattering (HEX) beamline. To mitigate the potential performance degradation due to the linear optics distortion, a local compensation scheme was adopted and confirmed with the online beam measurement. A feedforward control to enable a dynamic compensation of the linear optics distortion was deployed. It can maintain the storage ring lattice performance when the device main coil current ramps.
Paper: WEPL009
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL009
About: Received: 30 Mar 2023 — Revised: 07 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL011
Commissioning of orbit feedforward system for HEX superconducting wiggler at NSLS-II
3126
A 1.2-m-long superconducting wiggler with the peak field of 4.3 T and period length of 70 mm has been recently installed for the High energy Engineering X-ray (HEX) Diffraction beamline at Cell 27 of NSLS-II Storage Ring. The commissioning result for the orbit feedforward system will be presented, including the uncorrectable dispersive pattern in horizontal orbit and non-negligible hysteresis effects. The impact of large residual field integrals on the active interlock envelope will be also discussed.
Paper: WEPL011
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL011
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL013
Study of the systematic error contributions to the measurement of beam size using sextupole magnets
3130
We present a study of the systematic uncertainties in beam size determination using sextupole strength variations. Variations in strength of a sextupole magnet in a storage ring result in changes to the closed orbit, phase functions and tunes which depend on the position of the beam relative to the center of the sextupole and on the beam size. We take advantage of the beam-based measurements of sextupole alignment errors and calibration correction factors obtained in 2022 to improve our model of the Cornell Electron/positron Storage Ring optics and assess accuracy limits in the beam size determination. Two measurement sets for the 76 sextupole magnets are compared: 1) the commonly used method of measuring tune variation for a single sextupole strength change at a given set of beam positions in the sextupole, and 2) using the linear term in the dependence of orbit and quadrupole kicks resulting from a set of sextupole strength changes. The latter are determined from polynomial fits to the difference orbits, phase functions and tunes arising from the sextupole strength changes. The first analysis neglects the effect of the beam size, leading to a small error in the offset determination. The second method fully accounts for the beam size and gives a second estimate for the alignment error. The differing sources of uncertainty in the two methods are assessed and discussed.
Paper: WEPL013
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL013
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL014
Higher-order spin depolarization analysis
3133
Current and historic tracking studies of the RHIC accelerator lattice find difficulty in explaining the transmission efficiency of spin polarization from the AGS extraction to RHIC storage energies. In this paper, we discuss mechanisms that result in resonant depolarizing behavior, beyond the usual intrinsic and imperfection resonance structures. In particular, the focus of this paper will be on higher-order resonances that become apparent in the presence of snakes. The set of conditions that identify higher-order spin-orbit resonances are 𝜈 = 𝑗0 + 𝑗 ⃗ ⋅𝑄⃗for integers (𝑗0, 𝑗) ∈ ℤ^4, where 𝜈 is the spin tune and 𝑄⃗ contains the orbit tunes. Note that we do not use the closed-orbit spin tune 𝜈0 but rather the amplitude-dependent spin tune 𝜈(𝐽𝑥, 𝐽𝑦, 𝐽𝑧) that depends on the phase-space amplitudes. While Sibrian snakes keep 𝜈0 at 1/2, the amplitude-dependent spin tune can deviate from 1/2 and can cross resonances during acceleration.
Paper: WEPL014
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL014
About: Received: 03 May 2023 — Revised: 14 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL015
Generalized Gradient Field Description Using the Bmad and PTC Toolkits
3136
The Generalized Gradient (GG) formalism of Venturini and Dragt for describing static magnetic or electric fields has been implemented in the Bmad toolkit for accelerator simulations. In conjunction with this, a new method for calculating GG derivatives from a field table has been developed which avoids some of the problems of the Venturini and Dragt method. Generalized gradients are also implemented in the PTC toolkit developed by Etienne Forest which is interfaced to Bmad. This allows for construction of spin/orbital Taylor maps useful for nonlinear analysis and rapid tracking.
Paper: WEPL015
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL015
About: Received: 06 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL016
High angular magnification for accessing structural information in Ultrafast Electron Diffraction
3140
Pulsed electron beams probe the dynamics of matter out of equilibrium with high spatial and temporal resolution. Ultrafast electron diffraction in particular is sensitive to sub-angstrom, sub-picosecond scale atomic motion. To collect all the structural information available in an electron diffraction pattern, the experimentalist must control the angular magnification onto the detector plane. We present a case study demonstrating the advantage of angular magnification: investigating periodic strain in moiré materials. Strain waves with 10 nm wavelength appear in diffraction as satellites closely clustered around brighter Bragg peaks. We describe a quadrupole lens triplet that varies the effective drift distance $M_{12}$ between sample and detector from 80 cm to 8 m for our 140 keV electron beam, allowing us to zoom in on these moiré satellites. Three independently powered quadrupoles make it possible to eliminate astigmatism from a point-like probe. With the field strength achievable using quadrupole magnets, this magnification technique is also suitable for MeV beam energies.
Paper: WEPL016
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL016
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL017
Orbit-response based optics corrections for FCC-ee
3143
The new generation of storage rings aims to push the limits of the luminosity and the size of the electrons beam that can be achieved. One of such planned machines is the e+/e- Future Circular Collider (FCC-ee) with 100km circumference. The FCC-ee lattice components can be subject to random misalignments and field errors. These errors can adversely affect the beam's closed orbit and beam optics properties, resulting in a significant reduction in the future collider's performance. This issue requires linear optics correction methods to be utilized, One of these methods is linear optics from closed orbit (LOCO) in which the measured ORM is fitted to the lattice model in order to determine the appropriate quadrupole strengths. n this study we demonstrate the application of closed orbit-based optics correction LOCO for FCC-ee lattices. The code was implemented using the Python accelerator toolbox (PyAT). The impact of alignment errors on FCC the lattice optics parameters were studied.
Paper: WEPL017
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL017
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL018
Analysis of the Diamond-II booster dipole magnets
3147
As part of the Diamond-II upgrade project, the booster synchrotron is due to be replaced with a low-emittance solution that enables efficient injection into the Diamond-II storage ring. The new booster lattice uses cells of combined-function gradient bends that integrate dipole, quadrupole and sextupole components into single magnets, alternating between focussing and defocussing bends. Accurate modelling of these magnets in particle tracking codes is vital to ensure the beam dynamics is accurately simulated during the entire ramp. In this paper we report on the methods used to correctly model the Booster-II dipole magnets and summarise the impact on lattice performance.
Paper: WEPL018
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL018
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL019
BPM offset measurements at rapid cycling synchrotron in China Spallation Neutron Source
3151
The Rapid Cycling Synchrotron is the key part of the China Spallation Neutron Source with the repetion rate of 25Hz. The lattice of the RCS is based on triplet cells with the superperiod of four. Due to ultilizing the trim quadrupoles in June 2021, the BPM OffSets were carefully measured, and the beam operation is more steady. In this paper, we will review the preparation of BPM OffSets measurements with the virtual accelerator, and the results of the measurements with beam.
Paper: WEPL019
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL019
About: Received: 02 Apr 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL022
Emittance reduction of the actual Booster for Elettra2.0
3155
A crucial common parameter for the new 4th generation machines is the reduced dynamic aperture at injection point. Will be presented the analyzed strategies and what have already been done in order to reduce the emittance of the injected beam and garantee a good injection efficiency.
Paper: WEPL022
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL022
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL023
Progress of the FCC-ee optics tuning working group
3158
FCC-ee is a proposed lepton collider with a circumference close to 100 km to produce an unprecedented amount of luminosity. The FCC-ee optics tuning working group is addressing one of the most critical aspects of the FCC-ee, that is the recovery of the optics design performance in presence of realistic imperfections. Various teams from laboratories all around the world have got together to assess field quality tolerances and review and share experience gained at synchrotron light sources and lepton colliders such as SuperKEKB. This paper reports the latest results on optics measurements and tuning simulations for various techniques, the development of simulation tools, and possible layout design changes to optimize the tuning performance.
Paper: WEPL023
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL023
About: Received: 03 May 2023 — Revised: 28 Jun 2023 — Accepted: 28 Jun 2023 — Issue date: 26 Sep 2023
WEPL024
Impact of two-dimensional decoherence on the measurement of resonance driving terms
3162
In the presence of a tune spread induced by chromaticity or amplitude detuning, decoherence will lead to the damping of the beam centroid motion after a single transverse excitation. This in turn has implications for the analysis of turn-by-turn based optics measurements, as it affects the precision of the spectral analysis. In the past, it has been shown how the effect of decoherence on spectral lines in a single plane can be accounted for. In this paper, this work will be extended to include the effect from both transverse planes. The derivations are then applied on data taken at the IOTA ring at FNAL to study resonance driving terms.
Paper: WEPL024
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL024
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL025
Application of beam-based alignment to the CLEAR facility
3166
The CERN Linear Electron Accelerator for Research (CLEAR) has been operating since 2017 as a user facility providing beams for a large variety of experiments. Its RF photocathode-based linear accelerator can accelerate electrons up to 220 MeV with a bunch charge of 0.1-1.5nC with single or up to 150 bunches per train. The flexibility of providing various beam parameters following user demands brights drawbacks and complexity in operating the accelerator. Standard beam steering based on the sequential variation of quadrupole and corrector magnets, performed by an operator manually, results in a very time-consuming process. This paper presents a tool we developed for automatic and global Beam-Based Alignment (BBA) for CLEAR based on dispersion-free steering and one-to-one corrections to transport beams with various charges and time structures.
Paper: WEPL025
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL025
About: Received: 04 May 2023 — Revised: 14 Jun 2023 — Accepted: 14 Jun 2023 — Issue date: 26 Sep 2023
WEPL026
Derivation and interpretation of parameters describing betatron mismatch and chromaticity
3170
Expressions to quantify betatron mismatch and chromatic effects are frequently used in accelerator physics, but their derivations are not given in standard text books, making their interpretation difficult. First parameters describing betatron mismatch are introduced using normalization with respect to reference Twiss parameters describing a lattice. In a second step, the derivatives of these mismatch parameters with respect to the relative momentum offset are considered and lead naturally to the Montague W functions and a phase angle computed as well by standard lattice programs.
Paper: WEPL026
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL026
About: Received: 02 May 2023 — Revised: 05 Jun 2023 — Accepted: 05 Jun 2023 — Issue date: 26 Sep 2023
WEPL027
Limitations of radial magnetic field estimates from counter-rotating beams in an electro-static EDM ring
3173
Proposals to measure a possible Electric Dipole Moment (EDM) of protons in an electro-static machine are studied by a world-wide community. The machine is operated at the so-called magic energy to satisfy the "frozen spin" condition such that, without imperfections and the well-known magnetic moment of the particle, the spin is always oriented parallel or antiparallel to the direction of movement. The effect of a finite EDM is a build-up of a vertical spin component. A small average radial magnetic field leads as well to a build-up of a vertical spin component, which cannot be disentangled from the effect due to a finite EDM, and thus generates a systematic error of the measurement. Essential ingredients of the concept are to install the machine inside a state-of-the-art magnetic shielding and to measure the vertical orbit separation of two counter-rotating beams, enhanced by choosing a very low vertical tune, with high precision pick-ups. In this paper, we analyse limitations of this method and, in particular, the impact of wanted ("strong focusing" lattice) and unwanted variations of the betatron functions and of coupling.
Paper: WEPL027
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL027
About: Received: 02 May 2023 — Revised: 31 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL029
Mini-beta optics for the European Synchrotron Radiation Facility
3177
The ESRF presently operates with the HMBA lattice that features beta-functions of 6.9 m and 2.7 m in the horizontal and vertical planes at the center of the the straight sections. These are not optimal for a length of in-vacuum undulator of approximately 2 m that is used at ESRF. New optics with reduced beta functions at the center of the straight section were designed to better match the electron and photon beams, allow for a reduction of the in-vacuum undulator gap and increase the brilliance delivered to the beam line. This paper presents the optics design, brilliance calculation and plans for experimental validation at the ESRF.
Paper: WEPL029
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL029
About: Received: 30 Apr 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL030
Beam loading simulations in PyAT for the ESRF
3181
The Extremely Brilliant Source (EBS) at the European Synchrotron Radiation Facility (ESRF) is a 4th generation light source operating with a horizontal emittance of 135 pm. This low horizontal emittance reduces the lifetime in filling modes with high current per bunch. This will be alleviated in the future with an active 4th harmonic cavity. In order to simulate the effect of the 4th harmonic cavity on the EBS performance, beam loading needed to be added included to PyAT (Python – Accelerator Toolbox). Here, we introduce the beam loading model and show the benchmarking simulations with theory and other simulation codes.
Paper: WEPL030
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL030
About: Received: 03 May 2023 — Revised: 16 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL031
Status and recent developments of python Accelerator Toolbox
3185
The Accelerator Toolbox (AT) is a multipurpose tracking and lattice design code relying on a C tracking engine. Its MATLAB interface is widely used in the light source community for beam dynamics simulation and can be integrated in control systems through the MATLAB Middle Layer. In recent years major effort was made to develop a python interface to AT: pyAT. In this framework, several features were added to pyAT, in particular, the introductions of the 6D optics dynamic aperture and lifetime calculation, single and multi-bunch collective effects simulations and parallelized tracking capabilities. A python ring simulator was also developed based on pyAT for offline modeling of the accelerator control system. Following a presentation of the structure and main features of AT, an overview of these recent developments is provided.
Paper: WEPL031
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL031
About: Received: 30 Apr 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
Development of an ion-optical achromat for high-energy proton imaging
Lens based proton radiography is a powerful diagnostics technique capable of resolving ultra-fast processes on the ns-scale in dense matter with unprecedented micrometer spatial resolution. This unique performance is currently realized by the use of a chromatic imaging system consisting of four quadrupole magnets that are configured to suppress the most significant 2nd order position dependent chromatic aberrations of the proton distribution*. Systems of this kind are currently in operation in Germany (PRIOR-II at GSI, 4.5GeV p+) and in the US (pRad at LANL, 800 MeV p+). As energy dependent 2nd order chromatic aberrations cannot be cancelled by any means, many experiments using dense targets suffer from a reduced depth of field caused by a large amount of energy loss straggling. This leads to a degraded image quality and also limits the physics output of those experiments. In order to compensate for this, a prototype ion-optical achromatic imaging lens is currently being developed for low-energy 25MeV electron beams. Achromatic lenses are already in use at particle accelerator facilities in e.g. fragment separators, however, the developed system will be the very first of its kind designed solely for imaging purposes. The final 5-cell design consisting of 25 ion-optical elements has passed the design stage and is foreseen to be commissioned in 2024. It is planned to then expand this capability to the 800MeV proton beam of the LANSCE accelerator at LANL.
WEPL034
Simulation Studies of the Particle Dynamic in Beam: Internal Target and Beam-Beam Interactions in the Figure-8 Storage Ring(F8SR)
3189
The Figure-8 storage ring (F8SR) concept for fusion reaction research in context of astrophysics is under development at Frankfurt University. In contrast to traditional storage rings, a guiding longitudinal magnetic field is used for confinement of very low energy charged particle beams continuously with high transverse momentum acceptance. Due to the strong magnetic field level (B=6 T), low energy proton and ion beams (W < 1MeV) of several amperes can be confined. Many characteristic and unique features (e.g. injection system, collider mode) and key components were developed in the past. The current developments are concentrated on the design of a beam-target area and detectors. Particle-in-cell (PIC) simulation of high current beam propagation through a target area and interaction with an internal gas target will be presented and discussed. Possible space charge compensation through confined electrons will be assessed. Investigation of the large target area for colliding beam mode will be presented and discussed as well.
Paper: WEPL034
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL034
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL035
Beam dynamics in the NEWGAIN project at GANIL-SPIRAL2
3192
The NEWGAIN (NEW GAnil INjector) project aims at supplying higher mass-to-charge ratio ions (from A/Q=3 to 7) with an energy of 590 keV/A to the present SC-Linac of SPIRAL2. It comprises a new SC source, a dogleg LEBT, an 88 MHz RFQ, and a MEBT, optimized for a current of up to 350 uA of uranium. Additionally, an extension of the present LEBT is considered to merge into the new one. This paper presents the last layout and beam dynamics results for these new lines, including the mass resolution, chopping, admittance slit and tuning scheme as the Design Study Phase ends.
Paper: WEPL035
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL035
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL036
Update on the lattice design process of BESSY III: towards a baseline lattice
3196
The lattice design process for BESSY III is based on a systematic & deterministic approach where sub-structures of the MBA lattice are analyzed and optimized before the lattice is composed. During this process, 5 standardized Higher-Order-Multi-Bend-Achromat (HO-6MBA) lattices were developed utilizing different combinations of homogeneous and gradient bends in the unit and the dispersion suppression cell. All lattices yield basically the same emittance, momentum compaction factor, working point, maximal field strengths, and drift lengths. Therefore, they are equivalent to the linear optics. This enables us to attribute any differences in their nonlinear behavior to the specific lattice structure. A detailed description and analysis of the trade-offs of these standardized lattice structures are given. Based on this analysis, the choice of the BESSY III lattice type is motivated.
Paper: WEPL036
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL036
About: Received: 01 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL037
Robust design of modern Chasman-Green lattices – a geometric control theory approach
3200
Abstract A geometric control theory method is outlined & pre- sented to improve the on & off-momentum dynamic aper- ture for synchrotrons. And applied to the two lattice op- tions/solutions for BESSY III. A guideline is also provided for how to estimate the resulting performance for the “real lattice. The so-called tune confinement approach [32].
Paper: WEPL037
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL037
About: Received: 08 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL038
Model-independent determination of solenoid offsets in the Sealab Injector
3204
Sealab (SRF Electron Accelerator LABoratory) is composed of an SRF photo gun and an SRF booster, followed by a diagnostic line and a recirculation path for ERL applications. It is the follow-up project of bERLinPro, which ran from 2010-2020 at HZB. In an SRF injector, a single solenoid is sufficient to optimally focus the beam for small emittance. The alignment of the solenoid is crucial, as it is the dominant source of trajectory distortions in the facility. Polynomial Chaos Expansion (PCE) is a technique developed for risk management and uncertainty quantification. It is well suited for application in accelerators, although not well known. In this paper, PCE is used to set up a surrogate model from calculated or measured data to determine the misalignment of the solenoid in Sealab.
Paper: WEPL038
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL038
About: Received: 25 Apr 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
WEPL039
Further aspects of the deterministic lattice design approach for BESSY III
3208
In the lattice design of the BESSY II successor, the diffraction-limited, Multi-Bend-Achromat (MBA) storage ring BESSY III, HZB follows the approach of deterministic lattice design. MBA lattices are composed of rather simple sub-structures: the repetitive unit cell, two dispersion suppression cells at the end of the achromatic section, and the focusing doublet or triplet with the straight section. As demonstrated in earlier papers, these sub-structures can be strategically optimized, once the optimization criteria are clearly defined. This paper deals with the optimal distribution of the bending angle between the (identical) unit cells and the two dispersion suppression cells, aiming at the lowest emittance. Further, options for utilizing different numbers of chromatic sextupole families are investigated with respect to their impact on the tune shift with momentum. Finally, the need for and benefit of harmonic sextupoles are treated.
Paper: WEPL039
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL039
About: Received: 25 Apr 2023 — Revised: 15 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL040
Status and extended beam dynamics scenarios for the second injection beam line at MESA
3212
This report presents new investigations on beam dynamics for the separation beamline which allows to transport and compress electron bunches from the second electron source MIST to the first acceleration section of MESA. Several beamline configurations are compared concerning the capability for transport of elevated bunch charges.
Paper: WEPL040
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL040
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL042
Design of the gradient dipole magnet for LLICTF
3215
The Lanzhou Light Ion Cancer Therapy Facility (LLICTF) is a compact medical accelerator currently under construction. It is designed to treat cancer using a 230MeV, 30mA H+ beam and a 85MeV/u, 1mA 3He2+ beam. The facility comprises two ion sources, a low-energy beam-transport (LEBT), a Radio Frequency Quadrupole (RFQ), a medium-energy beam-transport (MEBT), and the main ring accelerating structure. Due to the presence of two ion sources, it is necessary to introduce a dipole magnet which is symmetrically focused as much as possible to meet the symmetrical focusing requirements of the LEBT beam. Therefore, a gradient dipole magnet has been designed to achieve this symmetrical focusing. This paper discusses the theoretical and simulated symmetric focusing of the gradient dipole magnet. It also analyzes the effect of fringe fields and space charge. Additionally, the paper presents the results of the model design with CST and the multi-particle simulation results with TraceWin.
Paper: WEPL042
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL042
About: Received: 13 May 2023 — Revised: 21 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
WEPL045
Employing octupole magnets for nonlinear optimization of Iranian Light Source Facility storage ring
3219
Limited dynamic aperture which is in the consequence of strong nonlinearities in a low emittance storage ring, is a challenging issue from beam dynamics point of view. In the present study, we have applied three families of focusing and defocusing octupoles to the storage ring lattice with the aim of increasing dynamic aperture and beam lifetime . We have discussed different methods to optimize of the position and strength of octupoles so that each octupole family fights a specific resonance driving term.
Paper: WEPL045
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL045
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL048
Transfer line design for EuPRAXIA@SPARC_LAB
3223
The transfer line that carries the electron beam from the plasma to the undulators is certainly a critical line in EuPRAXIA@SPARC\_LAB as in all plasma driven Free Electron Lasers. This machine section must serve multiple purposes: capturing the highly divergent bunches at the plasma exit, separating the driver bunch from the witness and finally matching the witness to the FEL undulators. In addition, the line must be as compact as possible so as to best contain the chromatic outbreak of the beam. In this paper we present the results of the design and optimization phase of the transfer line taking into account important collective effects such as space-charge and coherent synchrotron radiation emission in the chicane. Moreover, we show here our evaluations on the expected effect of chromatism after the plasma extraction on the witness and its core and the filtering procedure of the witness halo.
Paper: WEPL048
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL048
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
Scaling fixed-field alternating gradient-type magnets for transportation of laser-plasma accelerator electron beams
A beam transport section using the scaling fixed-field alternating gradient-type (FFAG) magnets is designed to transport laser plasma accelerator (LPA) electron beams to a specific application. This beam transport section has a large momentum acceptance, which is able to collect and transport the LPA beams with a momentum acceptance of up to 10%. Also, using the periodical FFAG magnet cells, the optical functions are identical at the beginning and end of this beam transport section, which makes it capable to be placed in any arbitrary designed beam transport line when transportation to a longer distance is required.
WEPL050
Design, fabrication and measurement of a normal conducting quadrupole for a laser-plasma-accelerator-based beam transport line
3227
For an experimental setup at the laser plasma accelerator (LPA) at the JETi Laser at Jena, Germany, an energy upgrade of a linear beam transport line has been studied. The transport line, originally designed to match the LPA beam to a transverse gradient undulator (TGU) at 120 MeV and successfully experimentally tested in 2014, will be upgraded to up to 300 MeV by employing stronger focusing quadrupoles. For these high strength quadrupoles, magnetic simulations as well as cooling and electrical calculations have been done. To develop fabrication procedures and magnetic measurement techniques, a prototype of the quadrupole magnet has been manufactured and tested at Karlsruhe Institute of Technology, Germany. This paper is presenting the design, fabrication and magnetic measurement of the first prototype quadrupole magnet.
Paper: WEPL050
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL050
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL052
Improved measurements of nonlinear integrable optics at IOTA
3230
Nonlinear integrable optics (NIO) are a promising novel approach at improving the stability of high intensity beams. Implementations of NIO based on specialized magnetic elements are being tested at the Integrable Optics Test Accelerator (IOTA) at Fermilab. One method of verifying proper implementation of these solutions is by measuring the analytic invariants predicted by theory. The initial measurements of nonlinear invariants were performed during IOTA run in 2019/20, however the covid-19 pandemic prevented the full-scale experimental program from being completed. Several important improvements were implemented in IOTA for the 2022/23 run, including the operation at higher beam energy of 150 MeV, improved optics control, and chromaticity correction. This report presents on the improved calibrations of the NIO for nonlinear invariant measurements.
Paper: WEPL052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL052
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL053
Experimental demonstration of a straight-merger beamline
3233
Merging beams from multiple beamlines is critical to energy-recovering linear accelerators and beam-driven wakefield accelerators. Recently, a "straight-merger" beam line was proposed as a compact beamline to merge beams. The concept is based on a deflecting cavity with a superimposed dipole field. It provides a large deflecting kick at the injection phase where the RF and magnetic kicks add up ("deflecting mode") while a beam injected at a phase where the RF and magnetic field cancel out does not experience any net kick ("transparent mode"). A proof-of-principle beamline of this concept was built at the Argonne Wakefield Accelerator and experimentally tested. This contribution will discuss the experimental performances of the beamline.
Paper: WEPL053
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL053
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL054
CEBAF Injector Model for K-Long bunch charge at 200 kV
3236
The upcoming Jefferson Lab K-Long experiment at Hall D will require unique beam conditions with a much lower bunch repetition rate and atypically high bunch charge. To optimize the Continuous Electron Beam Accelerator Facility (CEBAF) injector for this experiment, we performed Multi-Objective Genetic Optimization (MGO) using General Particle Tracer (GPT) to determine the magnetic elements and RF settings necessary for the K-long bunch charge (0.64 pC) at 200 kV. We also investigated the transmission and beam characteristics of low to high charge per bunch electron beams through the injector for simultaneous operations of all four CEBAF Halls and characterized the transmission as a function of the photocathode laser spot size and pulse length. Our findings provide valuable insights into optimizing the CEBAF injector for the Jefferson Lab K-Long experiment, as well as for other experiments with similar beam conditions.
Paper: WEPL054
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL054
About: Received: 02 May 2023 — Revised: 04 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL055
Beam study on low dispersion CEBAF arcs
3240
The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab employs recirculating linac SRF technology to generate a high polarization 12 GeV electron beam for nuclear physics users. New opportunities to study multipass energy recovery have also emerged with the proposal of a 5-pass energy recovery demonstration, ER@CEBAF. New beam optics with minimized beta functions have been developed and tested to avoid collective beam instabilities for multi-pass beams and meet the beam requirements of the nuclear physics community. To enable energy recovery for a common arc beam transport of five passes, achromatic and isochronous arc optics conditions were satisfied by re-designing the transverse optics of CEBAF. This paper focuses on beam studies conducted to study the newly-designed, low-dispersion, lowest energy arcs for CEBAF operations and ER@CEBAF.
Paper: WEPL055
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL055
About: Received: 03 May 2023 — Revised: 22 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL056
Re-design of CEBAF optics for ER@CEBAF
3244
ER@CEBAF is an effort to demonstrate multi-GeV multi-pass energy recovery with a low beam current in CEBAF. The race-track-shaped CEBAF geometry allows its linacs to accommodate multiple energy beams simultaneously. However, five energy recovery passes complicate the beamline optics design process. Individual recirculating arcs each transport one beam energy, and are shared between accelerating/decelerating beams. Present CEBAF optics needs to be redesigned to accommodate this additional multi-pass ER scheme. Isochronous arcs are retuned to match with the solutions obtained from optimized 10-pass beamline. In this paper, we discuss the optics redesign process with the existing beamline for ER@CEBAF.
Paper: WEPL056
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL056
About: Received: 03 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL057
Exploration of beamline configuration space for identifying robust quadrupole configurations
3248
Experimental beamlines often are regularly reconfigured to meet changing requirements of the experiments and to minimize beam losses. The configuration is usually done with the help of beam optics tools like MADX. These tools offer matching capabilities which allow to find solutions in terms of quadrupole strengths. However, such solutions are found by satisfying the given constraints only and do not take into account limited precision of actual quadrupole devices. Under the influence of quadrupole errors due to magnetic hysteresis, power converter trips etc, the original beamline optics often degrades. This results in beam losses or loss of focus at the experimental target. Readjustment of the optics costs valuable experiment time. Hence, it is desirable to operate a beamline configuration which not only meets the requirements but is also robust against quadrupole errors. Such a configuration will deviate from its nominal properties only by a small margin even when the quadrupole strengths deviate within specified intervals. We present the systematic exploration of beamline configuration space to identify robust configurations. The results are discussed for the BIGKARL beamline at Forschungszentrum Jülich and the findings are supported by experimental data.
Paper: WEPL057
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL057
About: Received: 08 Mar 2023 — Revised: 04 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
Korea-4GSR Lattice Update
Korea fourth generation storage ring (Korea-4GSR) is the low emittance storage with an emittance of 61 pm and a circumference of 800 m. The design has been updated to add an injection straight section, where the beta function intentionally made to have high value to relieve the requirement of the off-axis injection. With the injection straight section, the improvement of the injection efficiency was confirmed through the tracking simulation considering various storage ring errors. We also investigated the nonlinear properties of the updated lattice including intrabeam scattering effect and Touschek lifetime.
Current status of the storage ring design of Korea-4GSR
Korea-4GSR is a greenfield electron storage ring with circumference of 800 m and natural emittance of 60 pm. Preliminary conceptual lattice design of Korea-4GSR is fully periodic 28-cell H7BA. By keeping the conceptual design as much as possible, we have been exploring modification on the design for higher brightness and better nonlinear properties such as dynamic aperture and Touschek lifetime. We present which optics conditions can be satisfied upon the current lattice framework and how much cost is required in terms of magnet strengths and aperture radius.
WEPL060
An improved method for linear optics and coupling correction based on closed orbit modulation
3252
A new method is introduced to process the closed orbit modulation by two corrector magnets modulated with sinusoidal waveforms. The new method can extract linear optics information from tens of thousands of orbits and represent such information with only a few parameters per beam position monitor. The concise form makes it easy to fit for linear lattice errors. The method has been demonstrated for linear optics correction on SPEAR3 and NSLS-II storage rings. One iteration of optics correction, including data taking and lattice fitting, takes only tens of seconds.
Paper: WEPL060
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL060
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
WEPL062
RUEDI microscopy: solenoids or quadrupoles?
3256
RUEDI, the Relativistic Ultrafast Electron Diffraction and Imaging facility for the UK, is a planned facility that will deliver single-shot, time resolved, MeV electrons for imaging and ultrafast (~10 fs) diffraction. The facility naturally separates into two lines, both fed by the same RF gun. The first line is for microscopy and imaging whereas the second is dedicated to diffraction. Microscopy can be done in two ways, the first is by building a line with solenoid lenses and the second is by building the same line with quadrupole lenses. Here, we explore the advantages and disadvantages of both. Starting with a description of how the microscope is built using solenoids and extending this to look at various options with quadrupoles.
Paper: WEPL062
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL062
About: Received: 03 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
WEPL067
Field-adapted coordinate transformations for rotating and accelerating beams
3260
Many accelerators employ axisymmetric structures, such as RF cavities, induction cells, and solenoids, to accelerate and transport charged particle beams. To analyze the motion of the beam in solenoids, it is common to make a transformation to the rotating Larmor frame. In the presence of an electric field, this transformation can be modified to obtain further simplifications in the equation of motion. In this paper, we explore the use of a complex Larmor phase to simplify the equations of motion in the presence of simultaneous axial electric and magnetic fields, such as those found in the induction cells of a linear induction accelerator (LIA). We also analyze the corresponding envelope equation and find that the natural emittance in this frame can be expressed in terms of familiar quantities.
Paper: WEPL067
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL067
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL070
Status of the SOLEIL II robustness studies
3263
SOLEIL, the French third-generation synchrotron radiation facility, is in the TDR phase of its upgrade to a new fourth-generation synchrotron light source, called SOLEIL II. Its storage ring lattice design has evolved over the last year to better adjust its parameters taking into account the results of the mechanical integration, more realistic magnet design~[1], and the geometrical constraints for the extraction of the photon beams. A new configuration of girders has been introduced, and the correction strategies have been refined. A new corrector budget and updated results with more statistics are presented in this paper.
Paper: WEPL070
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL070
About: Received: 02 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL072
Progress on the New Booster for SOLEIL II
3267
The SOLEIL II storage ring project will require an injected beam with small transverse and longitudinal sizes. To meet this requirement, a new multi-bend 14BA Higher-Order Achromat lattice has been de-signed to reduce the booster emittance from the pre-sent 140 nm.rad to 5 nm.rad @ 2.75 GeV. In this paper we report the progress in the booster beam dynamics studies, considering the linac energy increase from 110 to 150 MeV, and all errors coming from injection mag-nets, injected beam parameters, booster magnets and RF system, whereas the resistive wall study is reported elsewhere. The progress in designing the magnets, the vacuum system, the ramped power supplies, and the diagnostics is presented.
Paper: WEPL072
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL072
About: Received: 26 Apr 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL073
The MAX-IV linac with variable bunch compressors
3272
Recent studies have shown that accelerating $+19^{\circ}$ off-crest in all RF cavities in the MAX-IV linac reduces voltage-induced timing jitter from the klystrons. The current bunch compressors in the linac have fixed first-order longitudinal dispersion, and the RF phase is varied to control the amount of compression. Variable bunch compressor designs have been considered at MAX-IV in recent years, these would allow us to regain control over compression while the accelerating phase is fixed to reduce timing jitter. Particle tracking studies have been performed on the MAX-IV linac with the addition of arc-like variable bunch compressors.
Paper: WEPL073
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL073
About: Received: 01 May 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL074
High accuracy optics measurement in J-PARC MR for 1.3 MW upgrade plan
3276
J-PARC MR is a high intensity synchrotron that accelerates protons from 3 GeV to 30 GeV. In MR, beam study for 1.3 MW upgrade plan is now in progress. The upgrade is done by shortening the repetition period and increasing the number of protons, and it is crucial to understand their effects on beam motion. Especially, the betatron function is one of the most important parameters that determines the beam motion. In MR, the betatron function has been measured by using turn-by-turn signal of the beam position monitor. Betatron function has been adjusted to match with model within 3% accuracy in relative error in low energy period. However, in evaluating the effects of space charge forces and eddy currents on beam optics whose impact will be largen by the upgrade, the accuracy of betatron function measurement during the injection and acceleration period will be even more important. In this study, we have attempt to match betatron function to model within 1% accuracy in relative error both in injection and acceleration period which has never been achieved in MR, by performing beta function measurement using COD response from the steering magnets in MR.
Paper: WEPL074
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL074
About: Received: 03 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
WEPL075
Modeling for the phased injector upgrade for 12 GeV CEBAF
3280
As a follow on to the 12 GeV upgrade to the Continuous Electron Beam Accelerator Facility, the front end of the DC photo-gun-based injector has gone through a phased upgrade. The first phase focused on the beamline between the gun and the RF chopper system, and the second phase addresses the beamline after the RF chopper system including replacing the capture section and quarter cryomodule with a new booster module containing a 2-cell and 7-cell cavity string. Throughout the design process, we maintained and developed three models, one for the existing injector and one for each of the upgrade phases. With these models, we evaluated proposed hardware upgrades, evaluated and determined optimized beamline element positions, developed buncher voltage requirements, and settings for optimal injector running. In this paper, we will describe the models and results from these various studies and provide a brief summary of Phase 1 commissioning.
Paper: WEPL075
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL075
About: Received: 02 May 2023 — Revised: 16 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL077
DDBA-H6ba lattice for the nanometer-emittance design of Hefei Light Source
3284
Recently, a double-double bend achromat (DDBA) lattice is designed for Hefei Light Source (HLS), a second-generation synchrotron radiation light source, which reduced the natural emittance a lot. In this paper, to further reduce the emittance and improve the brightness, a DDBA-hybrid 6BA lattice is proposed and applied to the design for the potential HLS upgrade. With more bending magnets, the emittance is significantly reduced from 36.4 nm∙rad to 1.8 nm∙rad at the cost of two short straight sections. After nonlinear dynamics optimization, the dynamic aperture and momentum aperture are large enough for the requirements from beam injection and lifetime.
Paper: WEPL077
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL077
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL078
Analyzing and optimizing dynamic aperture based on minimizing the fluctuation of resonance driving terms
3288
Minimizing resonance driving terms (RDTs) is a traditional approach to enlarge the dynamic aperture (DA) of a storage ring. However, small RDTs can not guarantee a large DA. In this paper, the fluctuation of RDTs along the ring is taken into consideration. A large number of nonlinear lattice solutions based on one double-bend achromat lattice are analyzed. The results show that minimizing the RDT fluctuations can more effectively enlarge the DA area than minimizing the commonly used one-turn RDTs. Also, reducing the third-order RDT fluctuations is beneficial for controlling the fourth-order RDTs and ADTS terms. Then we use it as an objective to optimize the nonlinear dynamics and good results are obtained.
Paper: WEPL078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL078
About: Received: 30 Apr 2023 — Revised: 04 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL080
Error study on Hefei Advanced Light Facility storage ring
3292
Hefei Advanced Light Facility (HALF) is a fourth-generation storage ring with an emittance lower than 100 pm∙rad. To assess the real performance, in this paper, static error effects are studied and corrected for HALF. Simulation corrections of closed orbit, linear optics and transverse coupling are presented and the results show that the HALF lattice has reasonable robustness. The emittance growth caused by error effects is acceptable and the nonlinear dynamics performance with errors considered is also favorable.
Paper: WEPL080
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL080
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL082
Design and validation of the LEBT for the project LINAC 7, a low-current low-energy compact LINAC
3295
In this paper we present the design and validation of a compact LEBT for the LINAC 7 project. Specifically, the LINAC 7 project focuses on building a new generation, low-energy, low-current compact accelerator. The core idea is to achieve an energy of 7 MeV in less than 12 m while maintaining enough current to generate isotopes for medical uses. Through this work we explain the procedure we followed for the design, including the tests that we carried out to reach the final result. This includes the iterations we needed to overcome various problems such as how to keep the LEBT compact and deal with cooling, when is the best time for packing factor calculation, how to solve mechanical problems,... Although this LEBT is intended to be used with protons, further simulations have been carried out to show that it could be used for other species as well.
Paper: WEPL082
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL082
About: Received: 28 Mar 2023 — Revised: 13 Jun 2023 — Accepted: 13 Jun 2023 — Issue date: 26 Sep 2023
Transport Line for Laser-Plasma Acceleration Electron Beam
The quest of laser plasma accelerators is of great interest for various applications such as light sources or high energy physics colliders. This research has led to numerous performance improvements, particularly in terms of beam energy versus compactness [1] and ultra-short bunch length [2]. However, these performances are often reached without the achievement of sufficient beam quality, stability and reproducibility. These are the objectives of PALLAS, a test facility at IJCLab, that aims to advance laser-plasma from *acceleration* to accelerators. To this end, one of the main lines of research is the electron beam control and transport. The primary goal is to have a lattice design that allows for a fine characterization of the output beam as a function of the laser-plasma wakefield acceleration target cell and laser parameters, while paying a particular attention to preserving the quality of the beam during its transport. I will present the approach, considered for PALLAS, on the problematic of chromaticity and divergence for the transport of laser-plasma accelerated electron beams.
WEPL084
Benchmarking for CODAL beam dynamics code: laser-plasma accelerator case study
3298
Laser-plasma electron beams are known for their large divergence and energy spread while having ultra-short bunches, which differentiate them from standard RF accelerated beams. To study the laser-plasma beam dynamics and to design a transport line, simulations with *CODAL* [1], a code developed by SOLEIL in collaboration with IJCLab, have been used. *CODAL* is a 6D 'kick' tracking code based on the symplectic integration of the local hamiltonian for each element of the lattice. *CODAL* also includes collective effects simulations such as space charge, wakefield and coherent synchrotron radiation. To validate the studies in the framework of Laser-Plasma Acceleratior developpement, results from *CODAL* have been compared to *TraceWin* [2], a well-known tracking code developed by CEA. The comparison has been made using the outcome of Laser WakeField Acceleration (LWFA) particle-in-cell simulations as initial start particle coordinates from a case study of PALLAS project, a Laser-Plasma Accelerator test facility at IJCLab.
Paper: WEPL084
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL084
About: Received: 03 May 2023 — Revised: 02 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
Combining multi-objective genetic algorithm and neural network dynamically for the complex optimization problems in accelerator physics
Neural network (NN) has been tentatively combined into multi-objective genetic algorithms (MOGAs) to solve the optimization problems in physics. However, the computationally complex physical evaluations and limited computing resources always cause the unsatisfied size of training set, which further result in the combined algorithms handling strict constraints ineffectively. Here, the dynamically used NN-based MOGA (DNMOGA) is proposed for the first time, which includes dynamically redistributing the number of evaluated individuals to different operators as well as some other improvements to handle constraint and preference of objectives. Radio frequency cavity is designed by this algorithm as an example, in which four objectives and an equality constraint (a sort of strict constraint) are considered simultaneously. As a result, DNMOGA considerably improves both the number and competitiveness of the final feasible individuals, and shows the potential to completely replace the manual procession in this question. In general, DNMOGA is instructive for dealing with the complex situations of strict constraints and preference in multi-objective optimization problems in accelerator physics. (The corresponding paper has been accepted).
WEPL087
Online optimization of SIRIUS nonlinear optics
3302
SIRIUS is the 4th generation storage ring-based synchrotron light source built and operated by the Brazilian Synchrotron Light Laboratory (LNLS). Beam accumulation at SIRIUS storage ring occurs in an off-axis scheme, using a nonlinear kicker (NLK), for which the efficiency depends on a sufficiently large dynamic aperture (DA). This work reports on the application of online optimization using the Robust Conjugate direction Search (RCDS) algorithm on SIRIUS sextupoles, which resulted in improvements to injection efficiency and DA in three different machine working tunes.
Paper: WEPL087
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL087
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL088
The impact of magnetic errors on the electron ion collider rapid cycling synchrotron
3306
The Rapid Cycling Synchrotron (RCS) of the Electron Ion Collider (EIC) is the injector of the Electron Storage Ring (ESR). The dynamic range of the RCS is from 0.4 GeV to 18 GeV. The RCS will use normal conducting dipoles, quadrupoles, and sextupoles. With errors to the main dipole field and misalignment to the elements included in the model, an orbit correction scheme has been developed. These magnet to magnet variations to the main field of the elements were studied as well as the effects of the multipole field errors. The impact of these errors and misalignments on the dynamic aperture will be presented.
Paper: WEPL088
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL088
About: Received: 02 May 2023 — Revised: 19 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL091
Fast RF tracking functions
3310
The beam dynamics of a bunch both longitudinally and transversely play a major role in the design process of an RF cavity, from the feasibility of cavity lengths, to the focusing schemes required to maximise capture. Often, computer simulations track particles using computationally intensive numerical techniques, which can be extremely time-consuming to run. In this paper, we present a generalised analytical method to track macro-particles through RF structures, computing the 6D phase space elements at the end of each RF cell. The results show strong agreement with the well-benchmarked tracking code, ASTRA, however requires a significant reduction in computing power and run time. The results from this paper present a very promising means of streamlining future tracking simulations by increasing the computing efficiency with no significant detriment in accuracy.
Paper: WEPL091
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL091
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL092
Dynamic aperture predictions with echo state networks
3313
The calculation of the volume of the phase-space stability region of hadron storage rings is currently performed through computer simulations of particles tracking in 6D coordinates, which are resource -and time- intensive processes. We have investigated in a previous paper the ability of an ensemble reservoir computing approach based on Echo State Networks to predict the long-term evolution of the radius of the phase-space region in which the motion of charged particles in hadron storage rings is bounded. Here, we perform a sensitivity analysis of the results of the Echo State Networks prediction with respect to different ways of splitting the original data set into a training, validation, and test set. This analysis confirms the validity of the splitting proposed in our previous paper and suggests that extending the validation phase too much is counterproductive.
Paper: WEPL092
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL092
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL093
Phase space control of transverse resonance island buckets at CESR
3317
Transverse resonance island buckets (TRIBs) have been successfully observed at the Cornell Electron Storage Ring (CESR) after optimizing the distribution of seventy-six sextupoles to achieve the desired amplitude-dependent tune shift and the resonant driving term near a third-order resonant line (3vx=2). A novel knob is created to adjust the resonant driving term h22000 while minimizing the change of h30000. Interestingly found from simulation, the knob can change the TRIBs locations in the phase space, which is then confirmed experimentally at CESR. Theoretical calculation of the fixed points (stable and unstable) in the phase plots are explored with PTC, which shows excellent agreement with the tracking results and provides theoretical understanding of the TRIBs in the phase space. In addition, the island locations in the real x-y space are explored by adjusting a skew quadrupole to change the x-y coupling.
Paper: WEPL093
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL093
About: Received: 01 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL094
The effect of insertion devices on beam dynamics for Elettra 2.0
3321
The effect of both existing and the planned insertion devices on linear optics, dynamic and momentum aperture was modeled using the kick map approach. Cross check for some IDs have been done with different tracking codes. Mitigation strategy for avoiding the crossing of a 4th order resonance line, excited by some of the IDs, is proposed.
Paper: WEPL094
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL094
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL096
Analysis of a double-resonance crossing for beam splitting
3325
Beam splitting can be performed by adiabatic crossing of a given one-dimensional non-linear resonance. This process is routinely used at the CERN PS to deliver the proton beam to the SPS fixed-target physics. To improve the efficiency of the intensity sharing between the various beamlets, a dipole kicker can be used to excite the beam during the resonance crossing process. This entails a double-resonance crossing phenomenon that will be described and discussed in detail in this paper.
Paper: WEPL096
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL096
About: Received: 02 May 2023 — Revised: 05 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL097
The adiabatic theory of the nonlinear coupling resonance crossing in circular accelerators
3329
In this paper, the nonlinear coupling resonance $2 Q_x -2 Q_y = 0$ is studied by means of a Hamiltonian model. The detailed analysis of its phase-space topology unveils the possible phenomena that can occur when crossing adiabatically such a resonance. These considerations are probed by means of numerical simulations carried out using a symplectic map and the results are presented and discussed in detail.
Paper: WEPL097
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL097
About: Received: 02 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL098
Numerical simulations of transverse nonlinear beam manipulations at the CERN PS
3333
A new set of nonlinear beam manipulations have been recently proposed, with the goal of extending the transverse beam splitting that is routinely used at the CERN PS to deliver beam to the SPS for fixed-target physics. Using a simple Hamiltonian model, it has been shown how the transverse emittances can be shared by crossing a two-dimensional nonlinear resonance. Moreover, it has been shown how an AC-dipole can be used to split transversely the beam. In this paper, numerical simulations of these manipulations performed using a realistic model of the PS ring, including longitudinal motion, will be presented and discussed in detail.
Paper: WEPL098
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL098
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL100
A Python API for the particle tracking code PLACET
3337
The tracking code PLACET is widely used in the linear collider community to simulate the beam dynamics. It is a powerful tool for analyzing the static and dynamic imperfections in the lattice and has many built-in correction techniques. The original PLACET code was written in C with a TCL interface. Detailed data analysis including plotting is often performed with other programming languages, primarily Python. This paper describes the project of the Python application programming interface (API) for PLACET.
Paper: WEPL100
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL100
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL101
Status of MAD-X V5.09
3340
MAD-X is a popular beam optics code used to design, model and operate a large number of synchrotons and linacs. In this paper, we present the features added in the most recent versions and improvements we intend to make in future releases. Physics models have been added and improved to support the needs of the Future Circular Collider (FCC) and the Electron Ion Collider (EIC), regarding machine-detector interface, complex beamline layouts, and synchrotron radiation. More precise physics models have been implemented for some elements, and a complete set of exact coordinate frame transformations are now available. The tracking module has been extended to support frozen space-charge models. To improve interoperability with scientific ecosystems, MAD-X relies on the cpymad Python interface which offers a fine-grained control of MAD-X simulations, exceeding the capabilities of the internal MAD-X language.
Paper: WEPL101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL101
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL102
Dynamic aperture studies for the first run of High Luminosity LHC
3344
Dynamic Aperture (DA) studies based on single-particle tracking simulations have proven to be a powerful tool for optimizing the performance of the Large Hadron Collider (LHC), as well as its future High-Luminosity upgrade (HL-LHC). The present paper presents the studies performed for the first year of HL-LHC operation at the beginning of the fourth operational run of the LHC. The main focus lies on the exploration of new optics scenarios such as flat optics, where the transverse beam sizes at the high-luminosity interactions points are not equal. Multi-parametric DA studies and Frequency Map Analysis are deployed to derive the best parameters for operation for the start and end of the luminosity leveling with flat optics.
Paper: WEPL102
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL102
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL103
Potential and constraints of a beam-beam wire compensator in the HL-LHC era
3348
The compensation of the long-range beam-beam interactions by DC wires is currently being investigated as an option for enhancing machine performance in the framework of the High-Luminosity LHC Project. In this paper, we report and comment on the potential of wire compensation during the first HL-LHC run. The results are based on numerical simulations and optimisations of the machine dynamic aperture varying the wire position and current, taking into account the latest optics and beam scenarios and the constraints imposed by the corresponding settings of the HL-LHC collimation system.
Paper: WEPL103
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL103
About: Received: 01 May 2023 — Revised: 08 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL105
Relativistic beam loading and recoil effects using a covariant, retarded-potential iterator
3352
A algorithm is demonstrated which performs first-principles tracking of relativsitic charged-particles for determining the power they deposit into their surroundings (in particular, blackbody cavities and pillbox accelerating cavities). A computationally costly, but highly accurate covariant approach is used, which employs retarded vector potentials for trajectory integration instead of performing field calculations. The peak vector potential and related Lorentz force in the direction of travel is shown to increase asymptotically for high $\beta$ particles approaching a conductive surface or another charged particle. This effect produces a very strong field distribution at small angles from the source particle's direction of travel, which, for high-intensity beams, can deposit significant power onto the surface surrounding a cavity's exit aperture. Changes in momentum of a charged particle occurring after a cut-off of external fields are shown to be non-conservative, such that any resulting power deposition causes a recoil effect on the cavity. We present benchmark cases for this framework and results for two-particle simulations as well as small-bunch simulations using a macroparticle formalism.
Paper: WEPL105
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL105
About: Received: 03 May 2023 — Revised: 18 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL106
Analytical potential model for the Radio-Frequency Quadrupole at the European Spallation Source
3356
The potential in the Radio Frequency Quadrupole (RFQ) can be expressed as a sum of a transverse multipolar expansion: $\sum_{m=1}^\infty{A_{0m}}\left(\frac{r}{r_0}\right)^{2m}\cos(2m\theta)$, and a longitudinal term expressed as sum of Bessel functions: $\sum_{m=0}^\infty\sum_{n=1}^\infty A_{nm}I_{2m}(nkr)\cos(2m\theta)\cos(nkz)$. Since the paper of Kapchinskii and Teplyakov \cite{osti_4032849} this potential is used considering only the first term in transversal and longitudinal components, unfortunately such approximation does not reproduce properly a realistic RFQ as the one installed at the European Spallation Source (ESS). In this paper we evaluate the potential when more terms are considered and we compare it with the field map obtained from a numerical Poisson solver used at ESS.
Paper: WEPL106
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL106
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
WEPL108
Experimental 4D tracking of a single electron in IOTA
3359
We present the results of the first experiments on 4-dimensional phase-space tracking of a single electron in a storage ring, using a linear multi-anode photomultiplier tube for simultaneously measuring transverse coordinates and arrival times of synchrotron-radiation pulses. During the next few months, full 6D tracking will be implemented. This technology makes it possible to characterize the motion of a single particle, i.e. simultaneously tracking of amplitudes and phases for slow synchrotron oscillations and fast betatron oscillations. Complete tracking of a single particle enables the first direct measurements of dynamical properties, including invariants, amplitude-dependent tunes, and chaotic behavior.
Paper: WEPL108
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL108
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL109
Further investigations of TRIBs in BESSY III design MBA lattices
3363
This paper is the follow-up of a previous one where we reported symmetry breaking as the main factor that establishes transverse resonance island buckets (TRIBs) close to a third-order random resonance in one of BESSY III design lattices by using a single knob. Here we present a more complete picture of the analytical framework and we show that there are two types of resonances close to which islands can be implemented. We give a brief overview of how this framework can be applied by using the BESSY III multibend-achromat (MBA) lattices as examples.
Paper: WEPL109
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL109
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL110
Nonlinear Dynamics of Scaling FFAs
3367
Fixed Field Alternating Gradient Accelerators (FFAs) that follow the conventional scaling law have – by definition – high order multipole components in their magnetic fields. It is the presence of these nonlinearities that in many cases determines several important properties of the machine, including amplitude-dependent tune shift and dynamic aperture. Consequently, understanding of the nonlinear dynamics in these machines can be critical to design and optimisation processes. Study of these properties is made challenging by the complicated nature of closed orbits in many FFAs and the presence of edge angle effects (which are exploited by design in certain lattice configurations, such as the F-D spiral design chosen as the baseline for the FETS-hFFA prototype ring). This poster presents a novel method of nonlinear analysis based on the combined application of harmonic analysis and truncated power series algebra-derived techniques.
Paper: WEPL110
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL110
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL111
Amplitude dependent tune shift measurements at KARA
3371
KIT operates the storage ring KARA (Karlsruhe Research Accelerator) as an accelerator test facility, which serves as a testbed for different electron beam-based experiments. Thus, it motivates to study the beam conditions extensively. To extend the existing characterisation of non-linear parameters, the amplitude dependent tune shift (ADTS) was measured. ADTS is typically controlled by octupole magnets in a storage ring, which are not available at KARA, but the installed insertion devices exert a certain octupole component on the beam resulting in a change of the ADTS. This contribution presents measurements of the amplitude dependent tune shift for different combinations of active insertion devices.
Paper: WEPL111
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL111
About: Received: 02 May 2023 — Revised: 29 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL112
Simultaneous Compensation of Third-Order Resonances at the FNAL Recycler Ring
3375
Third-order resonance lines will have a detrimental effect on the high-intensity operation of the Recycler Ring (RR), under the current Proton Improvement Plan (PIP-II) for the Fermilab Accelerator Complex. Increasing intensity will increase space charge effects, leading to the excitation of normal and skew sextupole lines. Dedicated normal and skew sextupoles have been installed in order to mitigate the effect of these resonance lines. By measuring the response matrix of the third-order Resonance Driving Terms (RDTs) to the currents of these dedicated elements, this study shows how several resonance lines can be compensated simultaneously. Resonance compensation is experimentally verified through loss maps and emittance growth measurements using the Ion Profile Monitor (IPM) system in the Recycler.
Paper: WEPL112
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL112
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL115
Strongly curved super-conducting magnets: beam optics modeling and field quality
3379
Superconducting dipoles with a strong curvature (radius smaller than 2 meters, for an aperture of about 100 mm and a length of 1-3 meters) are required for applications where compactness is key, such as the synchrotron and gantry for Carbon-ion therapy developed within the European program HITRIplus. Such magnets challenge several assumptions in the field description and put to the test the range of validity of beam optics codes. In particular, the equivalence that holds for the straight magnets between the transverse multipoles description obtained from the Fourier analysis (used for magnet design and measurements) and the Taylor expansion of the vertical field component along the horizontal axis (used in beam optics) is not valid any longer. A proper fringe field modelling also becomes important, due to the curved geometry and the aperture being large compared to the magnetic length. We explore the feasibility and the limits of modeling such magnets with optics elements (such as sector bends and multipoles), which allows parametric optics studies for optimization, field quality definition and fast long-term multi-pass tracking.
Paper: WEPL115
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL115
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL116
Analytic calculations of RDT and detuning generated by beam-beam collisions and wire correctors
3383
Formulae to compute the footprint (amplitude-dependent detunings) and Resonance driving terms RDT, generated by long-range beam-beam collisions and wire correctors have been implemented in a Python code. The paper briefly outlines the method and code and provides several examples of its usage. The maximum extent of the footprint (in geometric sense) can be efficiently computed.
Paper: WEPL116
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL116
About: Received: 05 May 2023 — Revised: 08 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
WEPL118
Adiabatic capture of longitudinal phase space
3387
Thus ends 63 years without a theory of longitudinal capture able to predict the final beam distribution and optimize the voltage law. We show the relationship between average values of the initial and final Hamiltonian is a universal function independent of voltage law, provided the adiabaticity parameter is small. The deviations from average are also given. This means the bunch profile and energy spectrum are predictable, without particle tracking. Beam measurements at the BNL AGS Booster and MedAustron are also reported.
Paper: WEPL118
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL118
About: Received: 01 May 2023 — Revised: 19 May 2023 — Accepted: 19 May 2023 — Issue date: 26 Sep 2023
WEPL119
Impact of Crab Cavity RF noise on the transverse beam profiles in the HL-LHC
3391
Crab Cavities (CCs) are a key component for the HL-LHC luminosity upgrade. To significantly reduce the Long-Range Beam-Beam (LRBB) effects a large crossing angle scheme is needed . The installation of 4 CCs per beam in each of the two main interaction points aims to restore the luminosity loss caused by the crossing angle. Noise injected through the Low-Level RF (LLRF) system in these cavities is known to be affecting the growth of the transverse bunch emittance. In this paper a new numerical study has been developed thanks to the new tracking tool Xsuite to study in depth this detrimental effect of both phase and amplitude LLRF noise. Both Long Range and Head On Beam Beam effects are included in the simulation together with the CC noise to evaluate the effects of the interplay between these strong non-linearities and the external noise. Furthermore, transverse bunch measurements show that the transverse distribution can be modeled as an heavy tailed q-Gaussian. To take this into account a particular focus is given to the linear matching and subsequent tracking of a multivariate q-Gaussian distribution in the lattice. The Emittance Growth Rate induced on both a Gaussian and a q-Gaussian bunch is computed. This study could serve as a basis to evaluate the cross-talk between the two beams introduced by their head-on interaction in this heavy tailed scenario.
Paper: WEPL119
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL119
About: Received: 01 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
Simulation of the field enhancement effect in type II superconductors for SRF applications
Modern SRF applications require precise control of a wide range of material properties, from microscopic material parameters to macroscopic surface structures. Historically, Nb has been the primary superconducting material in SRF cavities. The past decade has seen increasing amounts of research into the development of cavities using next generation materials, such as Nb3Sn. These materials have great promise for improving SRF performance, but their small coherence lengths require even greater control of surface and material defects. Mesoscopic simulation of superconductors has proven itself to be a powerful tool in SRF development, connecting the results of ab initio/quantum calculations to the mesoscopic structures of the material, allowing for investigation of many phenomena which are difficult to probe experimentally. One particular phenomenon of concern is the field enhancement effect, which causes increased magnetic field near rough surface features, potentially leading to vortex nucleation or other dissipative processes. We outline a two-domain finite element framework of the Time-Dependent Ginzburg-Landau equations which allows for the simulation of magnetic field enhancement due to supercurrent screening near rough surface features. We apply this framework to several different candidate surface structures which may occur in Nb3Sn, and determine their impact on dissipation and vortex nucleation. We discuss the implications of these results for SRF cavity design.
WEPL121
Dispersion relations for a cylindrical waveguide with multilayer walls
3395
An algorithm for determining the eigenvalues of the eigenfunctions of a multilayer cylindrical waveguide is constructed. A relationship is found between dispersion relations and impedances. A method for determining the resonant frequencies of the wake field in the linear and helical motion of a particle is described. The damping coefficients of eigenmodes at resonant frequencies are determined.
Paper: WEPL121
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL121
About: Received: 04 May 2023 — Revised: 06 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL123
Coupler design for THz DLW LINACs
3399
A promising approach for compact linear accelerators in the THz frequency range is based on dielectric-loaded waveguides (DLWs). Higher breakdown fields expected at THz frequencies should enable higher acceleration gradients. However, the accelerating mode of a cylindrical DLW (TM<sub>01</sub>) is not the fundamental and only mode inside the waveguide at operating frequency. Therefore, a method is required to ensure excitation of the proper mode only. Here we present a coupler design to convert the guided electromagnetic TE<sub>10</sub> mode in a rectangular waveguide to the TM<sub>01</sub> mode of a cylindrical DLW. The symmetry of the structure and its feeding waveguides allow us to suppress all undesired modes and consequently increase the coupling efficiency to the desired mode. Moreover, this configuration shows an extremely wide bandwidth and low quality factor suggesting the coupler is also suitable for short THz pulses.
Paper: WEPL123
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL123
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
WEPL124
Resistive wall impedance of multilayer beam pipes of general cross sections
3402
One of the interesting topics among accelerator physicists in the last decades has been the resistive wall impedance of vacuum chambers with general cross sections. The resistive wall impedance of a round pipe was calculated more than half a century ago, followed by parallel plates, rectangular pipes, and, in more recent years, oval shapes. Analytical solutions usually require some approximations to simplify them. It is possible to solve Maxwell's equations in the vacuum chamber with simulation codes in order to obtain an exact solution for Resistive wall impedance. Although some of them show promising results, the need for a versatile code that can calculate resistive wall impedance and wakefield in a general cross-section vacuum chamber is still necessary. VACI-suite is a finite element solver that tries to solve this problem. Compared to well-known theories and simulation codes for well-known geometries, the code's results show remarkable agreement.
Paper: WEPL124
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL124
About: Received: 10 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL125
General method of short-range wakefield calculation for corrugated structures of arbitrary shape
3405
Corrugated structures have been used widely in X-ray free-electron laser facilities for chirp control, fresh-slice applications, and diagnostics. In this paper, we present a general method for calculating the short-bunch wakefield of corrugated structures with arbitrary shapes. At zeroth order, we give analytical solutions via the method of conformal mapping. At first order, we give steady-state wake calculation by solving a set of integral equations.
Paper: WEPL125
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL125
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL126
Magnetic field tools, a C++/Python library for magnetic field processing
3409
Magnetic Field Tools is an open source library being developed by the Insertion Devices and Magnets group at the ESRF. It is dedicated to the analysis of static magnetic field values obtained from simulations and measurements. Magnetic field models such as 2D and 3D multipoles in various geometries, as well as boundary element models, can be built from sets of field samples. The library was designed in order to be easily extendable to other types of field models. It is implemented in C++ and a Python binding is available. Application to undulator magnets, 3D multipole fringe fields and solenoids will be presented.
Paper: WEPL126
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL126
About: Received: 27 Apr 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL127
Progress on Thor SCSI development
3413
Tracy, the code base used for designing synchrotron light sources with predictable performance, has been significantly refactored. Furthermore it now uses mad-ng gtpsa library. We describe the achieved progress, discuss its python interface. We show how to use it for achieving a robust design for a modern synchrhotron light source.
Paper: WEPL127
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL127
About: Received: 07 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
New Geant4 Simulation Model of Electromagnetic Processes in Oriented Crystals and its Applications in Accelerator Physics
Electromagnetic processes of charged particles interaction with oriented crystals provide a wide variety of innovative applications such as beam steering, crystal-based extraction/collimation of leptons and hadrons in an accelerator, a fixed-target experiment on magnetic and electric dipole moment measurement, a positron source for lepton and muon colliders, X-ray and gamma radiation source for radiotherapy and nuclear physics as well as plasma acceleration in the crystal media. One of the main challenges is to develop an up-to-date, universal and fast simulation tool to simulate these applications. We present a new simulation model capable to simulate both steering and radiation electromagnetic processes in oriented crystals implemented into the Geant4 simulation toolkit*. We validate the model with the experimental data and benchmark it with other simulations**. We discuss the advantages and perspectives of this model for the applications of oriented crystals mentioned above.
Development of Nonlinear Optics Simulation Using the Accelerator Code ACE3P
SLAC has been developing the parallel finite element electromagnetics simulation suite ACE3P (Advanced Computational Electromagnetics 3D Parallel) for accelerator modeling using high performance computing (HPC) platforms. ACE3P employs the parallel high-order finite-element method with conformal (tetrahedral) mesh for high-fidelity representation of geometry, and further accuracy can be obtained using quadratic surface and high-order elements resulting in reduced computational cost. Currently, the treatment of material properties applies to linear dielectrics and metals, wherein the electric displacement field is directly proportional to the electric field. There is a rapid need for new interaction regimes of high fields that would drive nonlinear response in materials which are in turn essential for novel accelerator applications. Moreover, efficient conversion between photons of different energies is needed for harmonic and THz generation, as well as quantum sensors which inherently require materials with second- or third-order optical nonlinearity. In this work we present the current status of the development of the nonlinear EM solver, in ACE3P which includes nonlinear response of the dielectric material. This utilizes parallel and scalable architecture to perform simulations and virtual prototyping on multiscale optical and quantum systems.
Progress of High-Efficiency L-Band IOT Design for Accelerator Applications at SLAC
Recent efforts at SLAC aim at developing high-power accelerators powered by compact, high-efficiency rf sources such as klystrons and Inductive output tubes (IOT). In particular, a high-efficiency IOT is an electron-beam-driven RF source employed in the UHF band that offers high efficiency at variable output power levels. Due to the improved linearity, high efficiency, and reduced size, it is the RF amplifier of choice in the TV broadcast market. Stellant Systems (formerly L3Harris Electron Devices) has long pioneered the IOT design and recently leveraged its power toward various accelerator applications [1]. In this talk, we show the progress of developing a 1.3 GHz HEIOT in terms of design and performance. We also show results of 3D space-charge beam dynamics simulation of an L-Band inductive output tube (IOT) RF electron gun using the accelerator code ACE3P as a transformative approach to HEIOT design. We also show an optimization scheme of the rf output cavities that results in >100 kW of average power with an upward of 80% power efficiency.
WEPL133
A space charge forces analytical model for emittance compensation
3417
Space charge forces represent main induced effects in an RF-injector that degrade the beam quality. In this scenario the laser distribution sent on the photocathode acquires an important role in the emittance compensation process, as the slice analysis shows. A novel model of space charge forces is proposed for bunch with arbitrary charge distribution to derive expressions of self-induced forces. As the performance of the fields near the cathode is under present analysis, we can investigate use of this model in low charge regime. Further, the model has been benchmarked with the behavior of the distributions present in the literature and studied for new ones. It has also been applied for the study of the optimization of a C-band hybrid photoinjector now being commissioned, thus explaining the factor two reduction of the emittance observed at the exit of the gun by changing the initial distribution at the cathode.
Paper: WEPL133
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL133
About: Received: 31 Mar 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
WEPL135
Evaluation of the impact of REBCO-coated conductors on the resistive wall impedance of the FCC-hh
3421
The beam screen for the Future Circular hadron-hadron Collider (FCC-hh) has a baseline design based on a copper (Cu) coating. Calculations have indicated that the resistive wall impedance will be the major contributor to the beam impedance for the FCC-hh at both injection and collision and that Cu might be on the limit to ensure beam stability. To increase the safety margin, it is desirable to reduce the resistive wall impedance. In this contribution, we present an approach to reduce the beam impedance based on the reduction of the surface resistance of the beam screen coating by using High-Temperature Superconductors based on REBaCu3O7-x coated conductors (REBCO-CCs). These HTS-CCs have transition temperatures around 90K, and critical current densities which are high enough even in the presence of strong magnetic field, being therefore good candidates to substitute Cu in the FCC-hh beam screen which will be operating at around 50K and under a magnetic field of 16T. Using experimental data generated on the surface impedance of REBCO-CCs, CST simulations have been performed and the beam impedance has been estimated for an elliptical beam screen with the same vertical dimensions as that of a pure Cu beam screen. A position and REBCO-CCs contribution dependence study to determine the optimum beam screen configuration will be shown. Resistive wall impedance studies using an ellipse is a step forward towards determining the performance of the REBCO-CCs on the FCC-hh beam screen.
Paper: WEPL135
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL135
About: Received: 08 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL136
Quadrupolar multibunch detuning in the ALBA storage ring
3425
Vacuum chambers of flat aspect ratio are source of a quadrupolar component of long-range resistive wall wake fields whose amplitude only depends on the trailing test particle. In multi-bunch filling this leads to an accumulation of the long-range quadrupolar resistive wall wake field which expresses in multi-bunch tune shifts on both planes. The tune shifts were measured at the ALBA storage ring and the results were compared to the model of Chao, Heifets and Zotter * and the model of Blednykh et al.**. As ALBA runs with only 8 insertion devices of which 3 are in-vacuum undulators in relatively short sections with low beta-functions, the quadrupolar detuning is dominated by dipolar vacuum chambers and the standard vacuum chamber around the ring. The effect of the in-vacuum undulators will be also discussed.
Paper: WEPL136
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL136
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL139
Analytical formulae for the longitudinal impedance of two parallel layers with arbitrary complex permittivity and permeability
3428
We adopt the standard field matching technique to solve the general electromagnetic problem consisting of two parallel layers with arbitrary complex relative permittivity and permeability. Analytical formulae for the longitudinal impedance are discussed in the general case, and in the specific case of a two-layer system consisting of a metal-coated ceramic chamber. The solution of the electromagnetic problem allows also for the calculation of the power density deposited on the metal coating, thus permitting to address the important issue of the ceramic chamber beam-induced heating. The analysis is discussed with the parameters of the NSLS-II storage ring.
Paper: WEPL139
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL139
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL140
Bunch lengthening by a third-harmonic cavity in a low-emittance ring
3432
A common feature in the design of low-emittance lattices is the small momentum compaction, which implies a short nominal equilibrium bunch length. A short bunch length can lead to beam-induced heating of the storage ring vacuum components, and, combined with the small transverse emittances, can degrade the beam quality and pose severe limitations on the beam lifetime. To mitigate the aforementioned issues and improve the lifetime and quality of the beam, a common procedure is to use a higher-harmonic cavity (HHC) system, which leads to an increase of the equilibrium bunch length without an increase of the energy spread. An important issue in the design of an HHC system is the proper choice of the multi-bunch configuration and the HHC parameters, both in terms of HHC performance limitations and beam stability. In this contribution we discuss numerical simulations of HHC effects, with parameters of a 3HC system for the NSLS-II low-emittance upgrade, addressing both beam stability and the performance limitation due to a gap in the uniform multi-bunch configuration.
Paper: WEPL140
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL140
About: Received: 04 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
WEPL141
Study of the combined effect of intrabeam scattering and impedance in a low-emittance ring
3436
Intra-beam scattering (IBS) is one of the prominent effects for low-emittance rings resulting in a significant growth of the emittance, energy spread, and bunch length. This effect is partially mitigated by the bunch lengthening caused by the longitudinal impedance. However, a significant bunch lengthening provided by higher-harmonic cavities is needed to keep the emittance low enough for achieving the designed brightness. For low-emittance lattices considered as options for the NSLS-II upgrade, we studied a combined effect of the IBS, impedance, and harmonic cavities using analytical formulae and computer simulations.
Paper: WEPL141
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL141
About: Received: 01 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL143
Impedance characterization of the RF-shielded bellows for Sirius SRF cavities
3439
Sirius is a 4th generation synchrotron light source at the Brazilian Center for Research in Energy and Materials in Campinas, Brazil. The storage ring is currently operating with a normal conducting seven-cell cavity and an upgrade of the whole RF plant is foreseen to take place in the beginning of 2024. Two CESR-B superconducting cavities will be installed in the storage ring and comb-type RF-shielded bellows will be placed in the 100 mm diameter sections. This paper presents the results of the bellows wakefield simulations carried on to estimate the power deposited by the beam, the thermal simulations and the status of the prototype.
Paper: WEPL143
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL143
About: Received: 02 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
WEPL144
Impedance measurements of key elements in the HEPS
3442
Impedance modeling is an important subject in diffraction limited storage rings based light sources, due to the adopted small beam pipe as well as the tight requirements from beam collective effects. Therefore, a batch of impedance bench measurements are performed or planned for the dominant impedance contributors in HEPS, including resistive wall impedance of the NEG coated vacuum chambers, as well as the geometrical impedance of components with large impedance for single element or that show large contributions due to large quantities. In this paper, the impedance measurement of the key elements in the HEPS will be discussed, and the main results are given and compared with the theoretical estimations.
Paper: WEPL144
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL144
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL146
Beam coupling impedance contribution of flange aperture gaps: a numerical study for Elettra 2.0
3446
The accurate analysis of any possible source of beam instability is mandatory for the design of a new particle accelerator, especially for high current and ultra low emittance synchrotrons. In the specific case of instabilities driven by the coupling between the charged particle beam and the electromagnetic field excited by the beam itself, the corresponding effect is estimated through the beam coupling impedance. The modeling of this effect is fundamental to perform a rigorous evaluation of the coupling impedance budget able to account for all devices present in the entire machine. To deal with this problem, this paper focuses on the estimation of the contribution of the joints lying between the different vacuum chamber sections, by performing a comparative numerical analysis that takes into account for different aperture gaps between the flanges. The results point out the criticality of many small-impedance contributions that, added together, must be lower than a predefined impedance threshold.
Paper: WEPL146
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL146
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL148
Overview of transverse instabilities in the CERN Proton Synchrotron
3450
During Long Shutdown 2 (2019-20), the injector chain of the Large Hadron Collider (LHC) has been upgraded to reach the High Luminosity LHC goals in terms of beam intensity and brightness. In the CERN Proton Synchrotron (PS), this upgrade consisted in hardware modifications to double the intensity at extraction, while preserving the transverse emittance available from the CERN PS Booster. The gradual beam brightness ramp-up in the PS after the restart in 2021 brought to light several impedance-induced instabilities. Each of these instabilities has been thoroughly studied in order to understand the impact of several key beam parameters (chromaticity, RF voltage, damper gain). Instability observations, mitigation strategies as well as comparisons with macroparticle tracking simulations will be presented in this paper.
Paper: WEPL148
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL148
About: Received: 02 May 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL149
Impedance-induced beam observables in the CERN Proton Synchrotron
3454
Impedance-induced tune shifts and instability growth rates in the CERN Proton Synchrotron are studied thanks to the recently updated impedance model of the machine. Calculation of these beam observables are obtained using both Vlasov solvers and macroparticle tracking simulations, and are compared with those observed during dedicated measurement campaigns. Thanks to improvements in the measurement procedure, including the careful monitoring of losses, bunch length, linear coupling and chromaticity, uncertainties on the tune shifts were noticeably reduced compared to previous years. Finally, the effect of linear chromaticity on tune shift slopes and growth rates has been examined, allowing for a detailed comparison with both past measurements and simulations.
Paper: WEPL149
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL149
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL150
Characterization of the longitudinal beam coupling impedance and mitigation strategy for the fast extraction kicker KFA79 in the CERN PS
3458
In the framework of the High Luminosity Upgrade of the LHC (HL-LHC) the beam intensity from the injectors must be doubled while keeping longitudinal beam parameters unchanged. As such, high-quality beams with high intensities are required also from the Proton Synchrotron (PS). The beam coupling impedance plays a crucial role and mitigation measures must be taken to remain within a stringent impedance budget. Kicker magnets are important contributors to the overall broadband impedance of the PS. Moreover, the detailed study of kicker impedances revealed additional resonant modes which may be critical for the beam stability. The longitudinal beam coupling impedance for the fast extraction kicker KFA79 is presented in this study, and a solution to reduce the impedance of the critical resonant modes is introduced. Electromagnetic (EM) simulations have been performed to determine the impedance behaviour. Finally, the insertion of transition pieces between magnet modules is presented as a measure for mitigating the low frequency resonant impedance contributions.
Paper: WEPL150
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL150
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL151
Update of the RF-Track particle tracking code
3462
The tracking code RF-Track has been updated to include a large set of single-particle and collective effects: beam loading in standing and travelling wave structures, coherent and incoherent synchrotron radiation, intra-beam scattering, multiple Coulomb scattering in materials, and particle lifetime. This new set of effects was focused on the simulation of high-intensity machines such as linacs for medical applications. In these apparatuses, the beam propagation into air and water significantly impacts the beam propagation to and through the patient. Now, these effects can be included by design. Additionally, RF-Track can now simulate the cooling channel of a future muon collider.
Paper: WEPL151
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL151
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL152
Beam loading effects in standing-wave linacs and their implementation into the particle tracking code RF-Track
3466
Accelerating technology is evolving towards compactness and high intensity. In such a scenario, beam loading effects result in significant energy losses for long trains of bunches. To address these effects, we generalised the Beam Loading module of the tracking code RF-Track to allow the study of beam loading independently of the particle type and velocity or the accelerating cavity design. This paper describes the implementation of this effect in standing wave (SW) structures. Particular attention has been devoted to guns for photoinjectors, where causality plays an important role, and one must address the non-ultrarelativistic behaviour of the emitted particles. Finally, we will discuss the simulation of these effects in the CLEAR facility at CERN.
Paper: WEPL152
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL152
About: Received: 04 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
WEPL153
Impedance analysis of deformable RF contact bridges for high luminosity LHC
3470
In order to maintain the continuity of the vacuum system wall and comply with beam stability limits, radio frequency contact bridges are utilised as transitional elements in beam vacuum line interconnections. These radio frequency contact bridges must absorb and correct longitudinal, angular, and transverse misalignments brought on by mechanical motions during assembly, alignment, operating phases and thermal influences during accelerator operation. A deformable thin-walled copper beryllium structure is the foundation of a novel deformable radio frequency contact bridge concept that satisfies the above criteria without using conventional sliding contacts. To assess the feasibility of implementing such deformable radio frequency contact bridges in the High-Luminosity LHC, the longitudinal, dipolar, and quadrupolar components of the beam impedance in the two transverse planes were determined using electromagnetic simulations.
Paper: WEPL153
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL153
About: Received: 06 Apr 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
WEPL154
Transverse beam coupling impedance studies at the CERN Proton Synchrotron Booster after the LHC Injectors Upgrade
3474
After the LHC Injectors Upgrade (LIU) project, the CERN Proton Synchrotron Booster (PSB) operates with a new injection kinetic energy of 160 MeV and an extraction energy of 2 GeV. In light of this, several measurements have been performed to characterize the behaviour of the accelerator in terms of beam stability and beam coupling impedance in the new energy range. In particular, the horizontal instability observed in 2021 at about 1.7 GeV (between the old and the new extraction energy) has been deeply investigated and betatron coherent tune shift measurements have been carried out to further benchmark the PSB transverse beam coupling impedance model. Regarding the horizontal instability, although a mitigation strategy has been identified, measurements and studies have been conducted to understand and explain its source.
Paper: WEPL154
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL154
About: Received: 28 Apr 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL155
Head-tail mode zero instability growth rate studies in the CERN SPS
3478
The growth rate of the Head-Tail mode 0 instability is related to the real part of the transverse beam coupling impedance. The SPS transverse impedance model, which includes the major impedance contributions in the machine, can be benchmarked through measurements of growth rates as a function of chromaticity. This paper summarizes the methodology established to explore a wider range of chromatic frequency shifts, and presents the measurements performed after the LHC Injectors Upgrade (LIU) for two sets of machine optics: nominal and low gamma transition. The measurements are compared with the current Impedance model to further study its degree of accuracy.
Paper: WEPL155
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL155
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL156
Transverse instabilities at injection energy in the CERN-SPS: lessons learned during high intensity studies
3482
Several studies have been performed in the 2021 and 2022 runs to build a better understanding of the behaviour of the accelerator with high intensity beams. Transverse beam instabilities at injection energy are known from previous measurements and simulations to be a potential limitation to reach the LHC Injectors Upgrade (LIU) target beam intensity. This paper summarizes the limitations introduced by transverse instabilities and the experience gained during 2021 and 2022 runs. Special emphasis will be given to the vertical coupled-bunch instability predicted by simulations and observed for the first time after the Long Shutdown 2 (LS2) during the 2021 run. This instability together with the horizontal one, which has been deeply characterized before LS2, is expected to impose constraints on the chromaticity, octupole current and tune working point. The stabilization strategy at the LIU intensity has been demonstrated during the 2022 run. Beam lifetime and quality for the explored operational settings will also be discussed.
Paper: WEPL156
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL156
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL157
Beam-induced heating mitigation of the SPS kickers: a crucial upgrade to move towards HL-LHC beam intensities
3486
Beam-induced heating of equipment can have several undesirable effects, including rendering the equipment temporarily inoperative, equipment degradation and/or damage. Hence, to avoid these problems, it can be necessary to limit beam intensity. Beam-coupling impedance mitigation of existing devices and/or design optimization of new accelerator elements are essentials to overcome these limitations. In this framework a very good example is the optimization of the SPS kickers beam-coupling impedance for beam-induced heating mitigation. This paper describes the beam-coupling impedance measurements and simulation studies performed to identify and potentially remove the intensity limitation arising from the excessive beam-induced heating of a SPS injection kicker.
Paper: WEPL157
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL157
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL158
Characterization of transverse profiles along the LHC injector chain at CERN
3490
Following the successful implementation of the LHC Injectors Upgrade (LIU) project, the CERN injectors were re-commissioned in 2021 and have been delivering beam to the LHC since 2022. The operationally delivered beam is well within the specifications regarding its brightness. However, heavy population of non-Gaussian tails of the transverse beam profiles were observed. These tails lead to high losses at LHC injection and degrade the luminosity reach of the LHC. This paper follows the studies to characterize the transverse profiles along the accelerator chain: the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS). The methodology to measure the emittance and the tail population as the studies aimed at reducing this population will also be discussed.
Paper: WEPL158
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL158
About: Received: 28 Apr 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL160
Loss simulations on shielding foil slit errors
3494
The worldwide first in-vacuum elliptical undulator, IVUE32, is being developed at Helmholtz-Zentrum Berlin. The 2.5 m long device with a period length of 3.2 cm and a minimum gap of about 7 mm is to be installed in the BESSY II storage ring. The device follows the Apple-II design and features four magnet rows. Both the two bottom and two top rows can be shifted longitudinally. This shift needs to be permitted by the shielding foils that cover the permanent magnets. The proposed solution calls for a longitudinal slit in the top and bottom shielding foils, which gets folded into the gap between the top and bottom magnet rows respectively. The manufacturer states that the folding process can introduce a small sinusoidal error to the slit width. We will present wakefield simulation studies that investigate the effect of different possible foil gap variations.
Paper: WEPL160
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL160
About: Received: 05 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
WEPL161
Stability survey of a double RF system with RF feedback loops for bunch lengthening in a low-emittance synchrotron ring
3498
Bunch lengthening with a double radio-frequency (rf) system combining fundamental and harmonic cavities (HCs) is essential in achieving extremely low emittance along with suitable lifetime as required for ring-based fourth-generation synchrotron light sources in the low-to-medium energy range. Recent studies have pointed out that, in many cases, an unstable beam motion, as so-called “periodic transient beam loading effect*1” or “coupled-bunch mode *l*=1 instability*2”, prevents from reaching the optimum bunch lengthening condition. One effective way to raise the bunch lengthening limit is to reduce the total R/Q of the HCs. However, there is also a limit to the reduction of their R/Q due to the need for generating sufficient HC voltage for bunch lengthening. We have then considered using active (powered) HCs with conventional rf feedback loops, coupled-bunch mode damper and direct rf feedback, which were modeled and introduced in the particle tracking code, mbtrack. The tracking results for the SOLEIL-II ring case show that the direct rf feedback is quite effective in suppressing the beam instabilities thanks to its ability of reducing the cavity impedance as seen by the beam. The features of the implemented rf feedback loops and the simulation results are reported.
Paper: WEPL161
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL161
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL162
Upgrade the impedance model in RCS of CSNS
3502
The Rapid Cycling Synchrotron (RCS) in China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, the impedance can drive collective instabilities and limit the machine performance. Due to new component installation, the impedance model should be updated. A thorough estimation of the coupling impedance is presented and the impedance model in the RCS is obtained.
Paper: WEPL162
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL162
About: Received: 04 May 2023 — Revised: 11 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL163
The impact of the resistive-wall impedance on the ILSF storage ring
3506
The resistive contribution of the vacuum chamber is a significant part of the impedance budget. Due to the NEG-coated re-designed ILSF vacuum chamber, the resistive-wall effects must be carefully studied. The resistive impedance of the insertion devices and general cross-section of the storage ring was calculated by CST and WI2D code. In addition, the fast-correctors containing a resistive insert with a conductivity different from the rest of the pipe were simulated in CST. Finally, the not negligible effect of the heat load and threshold current was studied. The single-bunch calculations were done by ELEGANT code. The final results in longitudinal and transverse planes are presented here.
Paper: WEPL163
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL163
About: Received: 10 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL164
Study of beam-beam interaction in FCC-ee including updated transverse and longitudinal impedances
3510
Beam-beam interaction in FCC-ee can be seriously affected by the vacuum chamber coupling impedance resulting in a safe tune areas reduction, tune shifts and spread, bunch length and energy spread variation. The interplay of the two effects have a drastic impact on the stability of colliding bunches and respectively on the achievable luminosity. In this paper beam-beam collisions in FCC-ee with 4 interaction points are studied including the updated transverse and longitudinal impedances.
Paper: WEPL164
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL164
About: Received: 26 Apr 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL165
Studies of FCC-ee single bunch instabilities with an updated impedance model
3514
The ongoing FCC-ee collider design aims at optimizing beam parameters and developing the different accelerators systems. For this reason, the coupling impedance modeling is in evolution following the design of the collider vacuum chamber and hardware components. Respectively, studies of collective effects and instabilities are continuously updated and refined. In this paper we describe the current FCC-ee impedance model and discuss results of the single bunch instabilities studies. Possible mitigation techniques for these instabilities are also considered.
Paper: WEPL165
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL165
About: Received: 20 Mar 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL167
Longitudinal beam dynamics for different initial distributions at cSTART
3518
The compact STorage ring for Accelerator Research and Technology (cSTART) project aims to store electron bunches of LPA-like beams in a very large momentum acceptance storage ring. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for cSTART to benchmark and emulate laser-plasma accelerator-like beams. In a second stage a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and Helmholtz Institute Jena (HIJ). With an energy of 50 MeV and damping times of several seconds, the electron beam does not reach equilibrium emittance within the storage time of about 100 milliseconds. Therefore, the initial phase space distribution influences the later dynamics and beam properties. We perform longitudinal particle tracking simulations to investigate the evolution of the bunch lengths and phase space densities for different initial beam distributions.
Paper: WEPL167
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL167
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL170
A generalized tool to compute wake potential and impedance from electromagnetic time domain simulations
3522
An important problem in present accelerators is the determination of the electromagnetic (EM) wakefields and their effect in the machine performance. These wakefields are generated inside the accelerator vacuum chamber due to the interaction of the particle beam with the surrounding structure. Among the properties that characterize their impact on the machine are the beam coupling Impedance in frequency domain, and the wake potential in time domain. An accurate evaluation of these properties is crucial to effectively predict dissipated power and beam stability. This paper presents an open-source tool that integrates the EM wakefields for general 3D structures and computes the wake potential and impedance for longitudinal and transverse planes. Its usefulness is verified with the open-source EM-solver WarpX and benchmarked with the commercial software CST Studio.
Paper: WEPL170
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL170
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
Impedance modeling for Korea’s fourth-generation storage ring
Recently, the Korean government decided to construct a fourth-generation storage ring (4GSR). Compared to a third-generation storage ring (3GSR), emittance is significantly smaller so that we can achieve higher photon beam brightness. This small emittance enables because of a multi-bend achromat (MBA) which necessitates high magnetic field gradients. Accordingly, the vacuum chamber aperture is several times smaller than the 3GSR and the small apertures lead to high impedances that cause various beam instabilities. Hence, estimating the impedance of the components and mitigating the beam instabilities are key tasks during the 4GSR construction. Here, we present the impedance of some Korea 4GSR components calculated through numerical and analytical methods.
WEPL176
Resistive-wall instability evaluation along the ramp in the SOLEIL II booster
3526
The ultra-low emittance specification of the SOLEIL II storage ring requires a challenging lattice design of the booster that will inject the beam into it. The dimension of the vacuum chamber in the new booster must be reduced compared to that in the present machine. The resistive-wall (RW) instability is then expected to become more important than in the current booster. However, the Amplitude-Dependent Tune Shift (ADTS) is also expected to be stronger due to the strong sextupole magnets necessary for chromatic error correction in the new lattice. It could then be an important effect in fighting against this instability. Therefore, evaluating this instability is important to ensure the machine's feasibility. This work studies the beam dynamics along the ramp in the RW instability regime using the code mbtrack2. The turn-by-turn tracking allows us to see the evolution of the beam thoroughly and understand how RW, synchrotron radiation, and ADTS impact the beam stability.
Paper: WEPL176
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL176
About: Received: 24 Apr 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL177
Instability consideration in the presence of passive superconducting harmonic cavities
3530
Passive superconducting harmonic cavities may cause two types of instabilities when operated in bunch lengthening mode. One is the mode-zero Robinson instability and the other is the periodic transient beam loading instability. In this paper, these two instabilities will be briefly introduced using the parameters of the Hefei Advanced Light Facility storage ring.
Paper: WEPL177
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL177
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
WEPL179
Longitudinal beam dynamics studies with a third harmonic RF system for ALBA-II
3534
The proposed upgrade of ALBA to a 4th generation light source, ALBA-II, will involve several changes in the beam dynamics. The most significant change in the longitudinal plane is the addition of a harmonic RF system, which is expected increase the bunch length by at least a factor of three and raise the Touschek lifetime by a similar amount. However, RF systems with harmonic cavities can be limited by their own set of instabilities, hindering them from achieving optimal working conditions and reducing their lengthening performance. In this context, we present a preliminary assessment of the beam stability of ALBA-II in terms of longitudinal dynamics, along with an evaluation of the RF system performance based on the chosen RF parameters.
Paper: WEPL179
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL179
About: Received: 03 May 2023 — Revised: 14 Jun 2023 — Accepted: 14 Jun 2023 — Issue date: 26 Sep 2023
WEPL180
Coupled-bunch longitudinal instabilities with a harmonic cavity
3538
We present a theory of coupled-bunch longitudinal instabilities for storage rings that employ a harmonic cavity to lengthen the bunch. We find growth rates associated with the m=0 and m=1 modes for both "optimally" and "overstretched" bunches; the former is a Robinson-like instability, while the latter corresponds to the "periodic transient beam loading" effect described in Ref *. By self-consistently including longitudinal feedback, we then show that controlling the instability may require feedback damping rates that are higher than the growth rate. For parameters considered, we find that controlling the the m=0 mode may require damping rates that are up to 2 times higher than the instability growth rate, while in many cases the m=1 mode cannot be stabilized with any feedback gain. We verify these predictions using particle tracking for APS-U like parameters.
Paper: WEPL180
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL180
About: Received: 01 May 2023 — Revised: 19 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
WEPL182
Coupled bunch stability with variable filling patterns in PETRA IV
3542
The PETRA IV upgrade project is aiming at building a 6 GeV diffraction-limited light source. The storage ring’s off-axis accumulation injection scheme will allow generating a wide range of filling patterns for the needs of photon science users. To preserve high beam quality and low transverse emittances it is imperative to ensure beam stability against collective effects. In this paper we investigate the impact of different filling patterns on the coupled-bunch stability in the ring using a semi-analytical Vlasov solver.
Paper: WEPL182
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL182
About: Received: 28 Apr 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL183
Advances in a perturbation theory for the microbunching instability in free-electron laser injectors
3546
The microbunching instability is one of the most significant effects, which can lead to a severe degradation of the beam quality in the linac section of free-electron lasers. Direct analytical treatment of the microbunching instability is however challenging. In particular when multiple bunch compression stages are considered, an exact closed-form expression for the charge density of the electron bunch typically cannot be derived. As a remedy, perturbative methods might be considered. Here, the instability is investigated by analyzing the propagation of small perturbations to an otherwise stable phase-space density. One such approach is based on the expansion of the collective Perron-Frobenius operator of the collective system into a Frechet-Taylor series. Applying the expanded Perron-Frobenius operator to a slightly perturbed phase-space density allows to derive closed-form expressions for the propagated perturbation term, potentially to arbitrary order. In this contribution new advances in a perturbation theory based on the Frechet-Taylor expansion of collective Perron-Frobenius operators are presented.
Paper: WEPL183
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL183
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
WEPL184
Analysis of single-bunch instabilities for Diamond-II
3550
Single-bunch instabilities are among the major effects limiting beam intensity in synchrotrons. In the case of a light source with ultra-low emittances, this might be a critical issue causing poor performance of the synchrotron. This study elaborates on the case of the Diamond-II storage ring showing the results of particle simulations for different configurations of the updated lattice and the impedance model. Alongside with the results of simulations, we present an updated database of the Diamond-II impedance. The resulting impedance-induced betatron tune shifts, bunch lengthening, and synchrotron phase shifts obtained in simulations agree with analytical predictions. We obtain optimal parameters for horizontal and vertical chromaticities for all possible lattice and impedance configurations considering chromaticity variation as one of the measures to mitigate single-bunch instabilities.
Paper: WEPL184
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL184
About: Received: 03 May 2023 — Revised: 17 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
WEPL185
Transverse impedance and beam stability studies for the muon collider ring
3554
In the framework of the International Muon Collider Collaboration, a 10 TeV muon collider ring is being studied, with the option of an intermediate 3 TeV collider stage. The decay of high-energy muons represents a great challenge in terms of heat load management and radiation shielding for the superconducting magnets of the collider ring. Materials such as tungsten are being considered to shield the cold bore of the magnets from decay products. The transverse beam coupling impedance and related beam stability have been investigated in detail for several vacuum chamber designs to identify the minimum vacuum chamber radius and transverse damper properties required for stable beams.
Paper: WEPL185
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL185
About: Received: 30 Apr 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL186
Transverse impedance and beam stability studies for the muon collider Rapid Cycling Synchrotrons
3558
The International Muon Collider Collaboration is currently investigating the possibility to build a muon collider with a center of mass energy of 3 TeV in a first phase, with an option to build a 10 TeV collider in a second phase. The muon beam decay is the global challenge of such a collider and fast acceleration is required to reach high luminosities. A series of three or four Rapid Cycling Synchrotrons are currently proposed as the last acceleration stage before injecting the muon beams into the collider ring. The transverse collective effects in these synchrotrons have been analysed in detail. Both the higher-order modes of the numerous RF cavities needed for the fast acceleration, and the ceramic chamber needed to avoid eddy current effects, have been looked at in detail along with possible mitigation measures. Promising results have been obtained considering for the moment a single muon bunch.
Paper: WEPL186
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL186
About: Received: 30 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL187
Transverse coupled-bunch instability driven by the resistive wall impedance at SuperKEKB
3562
The growth time of transverse coupled-bunch instability (TCBI) in the vertical direction was measured at SuperKEKB rings. Resistive wall (RW) impedance is the primary source of driving TCBI. As a collider, special vacuum chambers are remarkable sources of RW impedance in addition to RW impedance from regular chambers. Such chambers include collimators where the chamber gap is very small and interaction region where the vertical beta functions are very large. The classical theory of TCBI based on uniform filling patterns is used to estimate the growth time and compared with experimental results.
Paper: WEPL187
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL187
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
WEPL188
Studies of coupled-bunch instabilities in the HEPS booster
3566
The High Energy Photon Source (HEPS), which is a 6 GeV diffraction-limited storage ring (DLSR)-based synchrotron light source, is under construction in Beijing, China. HEPS consists of a Linac, a booster synchrotron, and a storage ring. The HEPS booster is proposed to operate in multi-bunch mode. And the 5-cell PETRA-type cavity, which is rich in high-order modes (HOMs), is chosen to be used in HEPS booster. For the related coupled-bunch instabilities (CBI), comprehensive studies are performed. In this paper, we present the studies of CBIs both at the two fixed energy points (500 MeV and 6 GeV) and with the consideration of the energy ramping process in the HEPS booster.
Paper: WEPL188
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL188
About: Received: 28 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL189
Simulation studies on longitudinal beam dynamics manipulated by corrugated structures under different bunch length conditions at KARA
3570
In the KIT storage ring KARA (Karlsruhe Research Accelerator), two parallel plates with periodic rectangular corrugations are planned to be installed. These plates will be used for impedance manipulation to study and eventually control the electron beam dynamics and the emitted coherent synchrotron radiation (CSR). In this contribution, we present simulation results showing the influence of different corrugated structures on the longitudinal beam dynamics and how this influence depends on the machine settings in the low momentum compaction regime, which are related to the bunch length changes.
Paper: WEPL189
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL189
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL190
Advanced studies for the dynamics of high brightness electron beams with the code MILES
3574
High brightness electron beams enable a wide spectrum of applications ranging from short wavelength radiation sources to high gradient wakefield acceleration. The rich dynamics that are intrinsic in charged particles accelerated in complex systems require a careful description in the analysis and design of a given machine, particularly regarding its stability. Numerous computer codes are in use by the accelerator community for such purposes. In particular, MILES is a simple tracking code we have developed that allows fast evaluations of collective effects in RF linacs. In this paper we extend the simple models previously developed to describe specific, diverse applications that can benefit from the fast simulation tools developed in MILES. Examples of this kind include particle driven acceleration schemes in a plasma where driver and witness beams propagate in the ``comb" pulse-train configuration. Specifically, we investigate the self-induced fields excited within both the rf-linac stage and the capillary. Further, we discuss additional advanced topics such as wakefield effects in planar FEL undulators and the emission of coherent synchrotron radiation in a magnetic chicane.
Paper: WEPL190
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL190
About: Received: 31 Mar 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
WEPL192
Ion trapping and instabilities in SLS 2.0
3578
Residual gas atoms, ionized by the electron beam, may create two effects in an electron accelerator. One is the trapping of ions in the beam channel by the Coulomb forces of the beam and the other is the fast beam ion instability, a dynamic mutual transverse oscillation between ions and electrons. While the strongly reduced beam emittance of the accelerator upgrade SLS 2.0 is helpful in that situation, it will not suppress ion related effects completely. To avoid ion trapping, a small ion clearing gap of 30 buckets is still required. Enlarged pressures of 1e-9 mBar, as expected before complete vacuum conditioning, may lead to sufficient build up of ions during the passage of the bunch train to provoke fast beam ion instabilities, requiring to employ multiple clearing gaps. At nominal conditions with 1e-10 mBar, a stable operation is expected.
Paper: WEPL192
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL192
About: Received: 26 Apr 2023 — Revised: 05 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
WEPL193
Russian quadruplet based electron optics for ultrafast electron microscopy
3582
With the development of Mega-electron-Volt ultrafast electron diffraction technology, electron microscopy based on photocathode radio-frequency (RF) electron guns has become a promising tool for high spatiotemporal resolution and shows obvious advantages of suppressing the space charge effect. An ultrafast electron microscopy is being developed at HUST. Russian quadruplet (RQ) based electron optics is selected to achieve simultaneous focusing and equal magnification in both vertical and horizontal directions. The RQ exit beam position must be highly dependent on the entrance beam position and independent of the entrance beam divergence to achieve a point-to-point image, which defines the first-order transfer matrix parameters. COSY INFINITY code is implemented for optics design. The simplified hard-edge model, the fringe field effects, and high-order lens aberrations are discussed and further optimized for the electron beam optics design.
Paper: WEPL193
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-WEPL193
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023