TY - CONF AU - Dhital, B. AU - Delayen, J.R. AU - Derbenev, Y.S. AU - Douglas, D. AU - Krafft, G.A. AU - Lin, F. AU - Morozov, V.S. AU - Zhang, Y. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Equilibria and Synchrotron Stability in Two Energy Storage Rings J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In a dual energy storage ring, the electron beam passes through two loops at markedly different energies E_{L}, and E_{H}, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and ERL equilibrium mode is the case where RF in two beam passes nearly cancels. Calculations based on linear transfer matrix formalism show that longitudinal stability exists for both SR mode and ERL mode in two energy storage rings. PB - JACoW Publishing CP - Geneva, Switzerland SP - 364 EP - 366 KW - electron KW - storage-ring KW - damping KW - simulation KW - focusing DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPGW104 UR - http://jacow.org/ipac2019/papers/mopgw104.pdf ER - TY - CONF AU - Wijethunga, S.A.K. AU - Benesch, J.F. AU - Delayen, J.R. AU - Hannon, F.E. AU - Krafft, G.A. AU - Mamun, M.A. AU - Palacios Serrano, G.G. AU - Poelker, M. AU - Suleiman, R. AU - Zhang, S. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Simulation Study of the Emittance Measurements in Magnetized Electron Beam J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Electron cooling of the ion beam is key to obtaining the required high luminosity of proposed electron-ion colliders. For the Jefferson Lab Electron Ion Collider, the expected luminosity of 10³⁴ 〖 cm〗⁻² s⁻¹ will be achieved through so-called ’magnetized electron cooling’, where the cooling process occurs inside a solenoid field, which will be part of the collider ring and facilitated using a circulator ring and Energy Recovery Linac (ERL). As an initial step, we generated magnetized electron beam using a new compact DC high voltage photogun biased at -300 kV employing an alkali-antimonide photocathode. This contribution presents the characterization of the magnetized electron beam (emittance variations with the magnetic field strength for different laser spot sizes) and a comparison to GPT simulations. PB - JACoW Publishing CP - Geneva, Switzerland SP - 822 EP - 825 KW - solenoid KW - emittance KW - cathode KW - electron KW - gun DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB110 UR - http://jacow.org/ipac2019/papers/moprb110.pdf ER - TY - CONF AU - Solopova, A.D. AU - Carpenter, A. AU - Iftekharuddin, K.M. AU - Powers, T. AU - Roblin, Y. AU - Tennant, C. AU - Vidyaratne, L. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - SRF Cavity Fault Classification Using Machine Learning at CEBAF J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab is the first large high power CW recirculating electron accelerator which makes use of SRF accelerating structures configured in two antiparallel linacs. Each linac consists of twenty C20/C50 cryomodules each containing eight 5-cell cavities and five C100 upgrade cryomodules each containing eight 7-cell cavities. Accurately classifying the source of cavity faults is critical for improving accelerator performance. In addition to archived signals sampled at 10 Hz, a cavity fault triggers a waveform acquisition process where 16 waveform records sampled at 5 kHz are recorded for each of the 8 cavities in the effected cryomodule. The waveform record length is sufficiently long for transient microphonic effects to be observable. Significant time is required by a subject matter expert to analyze and identify the intra-cavity signatures of imminent faults. This paper describes a path forward that utilizes machine learning for automatic fault classification. Post-training identification of the physical origins of faults are discussed, as are potential machine-trained model-free implementations of trip avoidance procedures. These methods should provide new insights into cavity fault mechanisms and facilitate intelligent optimization of cryomodule performance PB - JACoW Publishing CP - Geneva, Switzerland SP - 1167 EP - 1170 KW - cavity KW - cryomodule KW - SRF KW - operation KW - GUI DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUXXPLM2 UR - http://jacow.org/ipac2019/papers/tuxxplm2.pdf ER - TY - CONF AU - Stefani, M.S. AU - Gulliford, C.M. AU - Hannon, F.E. AU - Kostroun, V.O. AU - Mayes, C.E. AU - Poelker, M. AU - Smolenski, K.W. AU - Suleiman, R. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Magnetized Gridded Thermionic Electron Source J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. The demand for high average current for effective ion beam cooling has caused consideration of using bunched magnetized electron beam produced by a gridded thermionic electron gun. This paper presents the design of a potential electron source for JCIEC first measurements characterizing the beam properties of a magnetized thermionic gun. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2140 EP - 2143 KW - electron KW - gun KW - cathode KW - emittance KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS093 UR - http://jacow.org/ipac2019/papers/tupts093.pdf ER - TY - CONF AU - Zhang, S. AU - Adderley, P.A. AU - Benesch, J.F. AU - Bullard, D.B. AU - Delayen, J.R. AU - Grames, J.M. AU - Guo, J. AU - Hannon, F.E. AU - Hansknecht, J. AU - Hernandez-Garcia, C. AU - Kazimi, R. AU - Krafft, G.A. AU - Mamun, M.A. AU - Poelker, M. AU - Suleiman, R. AU - Tiefenback, M.G. AU - Wang, Y.W. AU - Wijethunga, S.A.K. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - High Current High Charge Magnetized and Bunched Electron Beam from a DC Photogun for JLEIC Cooler J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A high current, high charge magnetized electron beamline that has been under development for fast and efficient cooling of ion beams for the proposed Jefferson Lab Electron Ion Collider (JLEIC). In this paper, we present the latest progress over the past year that include the generation of picosecond magnetized beam bunches at average currents up to 28 mA with exceptionally long photocathode lifetime, and the demonstrations of magnetized beam with high bunch charge up to 700 pC at 10s of kHz repetition rates. Detailed studies on a stable drive laser system, long lifetime photocathode, beam magnetization effect, beam diagnostics, and a comparison between experiment and simulations will also be reported. These accomplishes marked an important step towards the essential feasibility for the JLEIC cooler design using magnetized beams. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2167 EP - 2170 KW - cathode KW - laser KW - electron KW - gun KW - emittance DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS105 UR - http://jacow.org/ipac2019/papers/tupts105.pdf ER - TY - CONF AU - Stefani, M.S. AU - Hannon, F.E. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Transverse Uncorrelated Emittance Diagnostic for Magnetized Electron Beams J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. In this paper, a new diagnostic is described with the purpose of studying transverse magnetized beam properties. The device is a modification to the classic pepper-pot, used in this novel context to measure the uncorrelated components of transverse emittance in addition to the typical effective emittance. The limitations of traditional methods are discussed, and simulated demonstrations of the new technique shown. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2745 EP - 2748 KW - emittance KW - electron KW - diagnostics KW - simulation KW - cathode DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPGW108 UR - http://jacow.org/ipac2019/papers/wepgw108.pdf ER - TY - CONF AU - Stefani, M.S. AU - Park, G.-T. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Double Quarter Wave Deflector Cavity Design & Simulation J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A Double Quarter Wave (DQW) Cavity has been designed, tested and installed for use in longitudinal measurements as part of a diagnostic beamline. This report will describe the design and testing used to characterize this cavity before its use in the study of a magnetized electron beam. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2749 EP - 2751 KW - cavity KW - coupling KW - operation KW - simulation KW - diagnostics DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPGW109 UR - http://jacow.org/ipac2019/papers/wepgw109.pdf ER - TY - CONF AU - Morozov, V.S. AU - Adams, P. AU - Derbenev, Y.S. AU - Filatov, Y. AU - Huang, H. AU - Kondratenko, A.M. AU - Kondratenko, M.A. AU - Lin, F. AU - Méot, F. AU - Ptitsyn, V. AU - Schmidke, W.B. AU - Zhang, Y. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - EXPERIMENTAL VERIFICATION OF TRANSPARENT SPIN MODE IN RHIC J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The transparent spin mode has been demonstrated in simulations and we now plan to test it experimentally. We present a design of an experiment using a polarized proton beam stored in one of the RHIC rings. In the experiment, one of the RHIC rings is configured in the transparent spin mode by aligning the axes of its two Siberian snakes. The experiment goals, procedures, hardware requirements and expected results are presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2783 EP - 2786 KW - polarization KW - collider KW - controls KW - experiment KW - resonance DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPGW122 UR - http://jacow.org/ipac2019/papers/wepgw122.pdf ER - TY - CONF AU - Morozov, V.S. AU - Adams, P. AU - Derbenev, Y.S. AU - Filatov, Y. AU - Huang, H. AU - Kondratenko, A.M. AU - Kondratenko, M.A. AU - Lin, F. AU - Méot, F. AU - Ptitsyn, V. AU - Schmidke, W.B. AU - Zhang, Y. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Spin Response Function for Spin Transparency Mode of RHIC J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In the Spin Transparency (ST) mode of RHIC, the axes of its Siberian snakes are parallel. The spin tune in the ST mode is zero and the spin motion becomes degenerate: any spin direction repeats every particle turn. In contrast, the lattice of a conventional collider determines a unique stable periodic spin direction, so that the collider operates in the Preferred Spin (PS) mode. Contributions of perturbing magnetic fields to the spin resonance strengths in the PS mode are usually calculated using the spin response function. However, in that form, it is not applicable in the ST mode. This paper presents a response function formalism expanded for the ST mode of operation of conventional colliders with two identical Siberian snakes in the highly-relativistic limit. We present calculations of the spin response function for RHIC in the ST mode. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2791 EP - 2793 KW - resonance KW - collider KW - polarization KW - controls KW - lattice DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPGW124 UR - http://jacow.org/ipac2019/papers/wepgw124.pdf ER - TY - CONF AU - De Silva, S.U. AU - Delayen, J.R. AU - Morozov, V.S. AU - Park, H. AU - Sosa, S. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Analysis of Higher Order Multipoles of the 952.6 Mhz RF-Dipole Crabbing Cavity for the Jefferson Lab Electron-Ion Collider J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The crabbing system is a key feature in the Jefferson Lab Electron-Ion Collider (JLEIC) required to increase the luminosity of the colliding bunches. A local crabbing system will be installed with superconducting rf-dipole crabbing cavities operating at 952.6 MHz. The field non-uniformity across the beam aperture in the crabbing cavities produces higher order multipole components, similar to that which are present in magnets. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system. In this paper, we quantify the multipole components and analyse their effects on the beam dynamics. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2996 EP - 2998 KW - cavity KW - multipole KW - dipole KW - HOM KW - electron DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB076 UR - http://jacow.org/ipac2019/papers/weprb076.pdf ER - TY - CONF AU - De Silva, S.U. AU - Delayen, J.R. AU - Li, Z. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2999 EP - 3002 KW - HOM KW - cavity KW - dipole KW - luminosity KW - damping DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB077 UR - http://jacow.org/ipac2019/papers/weprb077.pdf ER - TY - CONF AU - Park, H. AU - De Silva, S.U. AU - Delayen, J.R. AU - Sosa Guitron, S.I. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Design of a Proof-of-principle Crabbing Cavity for the Jefferson Lab Electron-ion Collider J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3027 EP - 3030 KW - cavity KW - electron KW - HOM KW - collider KW - luminosity DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB093 UR - http://jacow.org/ipac2019/papers/weprb093.pdf ER - TY - CONF AU - Pudasaini, U. AU - Ciovati, G. AU - Eremeev, G.V. AU - Kelley, M.J. AU - Parajuli, I.P. AU - Reece, C.E. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Recent Results from Nb₃Sn-Coated Single-cell Cavities Combined with Sample Studies at Jefferson Lab J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The critical temperature (~ 18 K) and superheating field (~ 425 mT) of Nb₃Sn are almost twice that of niobium, thereby promising the higher quality factor and accelerating gradient at any given temperature compared to traditional SRF cavities made of niobium. It can enable higher temperature for cavity operation (4 K Vs. 2 K), resulting in significant reduction in both capital and operating cost for the cryoplant. Several single-cell cavities along with witness samples were coated with Nb₃Sn to explore, understand and improve the coating process for betterment of cavity performance. RF measurements of coated cavities combined with material characterization of witness samples were employed to update the coating process. Following some modifications to the existing coating process, we were able to produce Nb₃Sn cavity with quality factor ≥ 2.10¹⁰ for accelerating gradient up to 15 MV/m at 4 K, without any significant Q-slope. In this article, we will discuss recent results from several Nb₃Sn coated single-cell cavities combined with material studies of witness samples. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3066 EP - 3069 KW - cavity KW - experiment KW - SRF KW - superconductivity KW - niobium DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB110 UR - http://jacow.org/ipac2019/papers/weprb110.pdf ER - TY - CONF AU - Huang, H. AU - Lin, F. AU - Morozov, V.S. AU - Neththikumara, I. AU - Roblin, Y. AU - Sosa, S. AU - Sy, A.V. AU - Terzić, B. AU - Zhang, Y. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Beam-Beam Effect: Crab Dynamics Calculation in JLEIC J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such a framework where the beam dynamics around the ring is tracked using Elegant and the beam-beam kick is modeled in Python. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3293 EP - 3296 KW - simulation KW - luminosity KW - collider KW - electron KW - cavity DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS073 UR - http://jacow.org/ipac2019/papers/wepts073.pdf ER -