TY - CONF AU - Lin, X. AU - Chen, H.B. AU - Liu, Z.N. AU - Shi, J. AU - Wu, X.W. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Analysis and Simulation of the "After-Pulse" RF Breakdown J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - During the high power experiment of a single-cell standing-wave accelerating structure, it was observed that many RF breakdowns happen when the field inside cavity is decaying after the input rf pulse is off. The distribution of breakdown timing shows a peak at the moment of RF power switches off. A series of simulation was performed to study the after-pulse breakdown effect in such a standing-wave structure. A method of calculating poynting vector over time is proposed in this article to study the modified poynting vector at critical points in the cavity. Field simulation and thermal simulation were also carried out to analyse possible reasons for the after-pulse breakdown effect. PB - JACoW Publishing CP - Geneva, Switzerland SP - 196 EP - 199 KW - cavity KW - simulation KW - timing KW - GUI KW - experiment DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPGW047 UR - http://jacow.org/ipac2019/papers/mopgw047.pdf ER - TY - CONF AU - Shao, J.H. AU - Chen, H.B. AU - Conde, M.E. AU - Doran, D.S. AU - Ha, G. AU - Jing, C.-J. AU - Liu, W. AU - Peng, M.M. AU - Power, J.G. AU - Seok, J. AU - Shi, J. AU - Whiteford, C. AU - Wisniewski, E.E. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Generation of High Power Short Rf Pulses using an X-Band Metallic Power Extractor Driven by High Charge Multi-Bunch Train J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Short pulse two-beam acceleration (TBA) is a structure wakefield acceleration (SWFA) approach aiming to achieve gradient above 250 MV/m using rf pulses less than 20 ns. An X-band 11.7 GHz metallic power extractor has been developed as the power source to test accelerating structures in this extreme regime. The power extractor is designed to be driven by high charge bunches separated by 769.2 ps (9 times the X-band period) on an L-band 1.3 GHz beamline. In the recent experiment, ~280 MW rf pulses with 3 ns flat-top have been measured by a coaxial rf pickup when driven by 8-bunch trains with a total charge of ~500 nC. The power level is ~50% lower than the theoretical prediction and simulation. Experimental investigation suggests that the missing power was mainly caused by the multipacting issue inside the rf pickup, which could be eliminated by a newly-designed directional coupler. PB - JACoW Publishing CP - Geneva, Switzerland SP - 734 EP - 737 KW - pick-up KW - experiment KW - multipactoring KW - acceleration KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPRB069 UR - http://jacow.org/ipac2019/papers/moprb069.pdf ER - TY - CONF AU - Ma, P.F. AU - Guan, X. AU - Tang, R. AU - Wang, X.W. AU - Xing, Q.Z. AU - Yu, X.D. AU - Zheng, S.X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Primary Beam Dynamics Design of a Heavy-Ion IH-DTL With Electromagnetic Quadrupoles J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A new IH-DTL beam dynamics scheme, IH-EMQ (ElectroMagnetic Quadrupole) is presented to obtain a large longitudinal acceptance. In this scheme, electromagnetic quadrupoles are installed inside the drift tubes of IH-DTL. A large-longitudinal-acceptance heavy-ion IH-DTL design is described in this paper. With the limit current of 25 mA, the 90% normalized longitudinal acceptance reaches 87.8 pi.deg. MeV for the 60 MeV 107Au³⁰⁺, which is 8 times of the input emittance. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1140 EP - 1143 KW - DTL KW - quadrupole KW - focusing KW - rfq KW - cavity DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPTS111 UR - http://jacow.org/ipac2019/papers/mopts111.pdf ER - TY - CONF AU - Ma, P.F. AU - Guan, X. AU - Pu, Y.H. AU - Qiao, J. AU - Tang, R. AU - Wang, C.P. AU - Wang, X.W. AU - Xie, X.C. AU - Xing, Q.Z. AU - Yang, F. AU - Yu, X.D. AU - Zheng, S.X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Matrix Approach to Decouple Transverse-Coupled Beams J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Transverse emittances, especially vertical emittance, are strictly required in the synchrotrons with multi-loop injection. Transverse emittances easily grow up if transverse beam phase spaces are coupled. The growth of the transverse emittance can be restained by decoupling the beam phase spaces. Based on the transfer matrix calculation, it can be theoretically proved that the decoupling can be implemented for general situations. A minimum number of rotated quadrupoles required for decoupling is given. Two quadrupoles can decouple the beam and suppress its emittance growth to 1% in the coupling DTL case. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1144 EP - 1147 KW - coupling KW - quadrupole KW - emittance KW - solenoid KW - DTL DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-MOPTS112 UR - http://jacow.org/ipac2019/papers/mopts112.pdf ER - TY - CONF AU - Li, D. AU - Feng, H.Q. AU - Filippetto, D. AU - Johnson, M.J. AU - Lambert, A.R. AU - Luo, T.H. AU - Mitchell, C.E. AU - Qiang, J. AU - Sannibale, F. AU - Staples, J.W. AU - Virostek, S.P. AU - Wells, R.P. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Recent Progress on the Design of Normal Conducting APEX-II VHF CW Electron Gun J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced Photo-injector EXperiment-II) at Lawrence Berkeley National Laboratory. APEX-II is an upgrade of the successful APEX gun and the LCLS-II (Linac Coherent Light Source-II) injector, aiming at applications for Free electron laser (FEL) such as LCLS-II High Energy upgrade, UED (Ultrafast Electron Diffraction) and UEM (Ultrafast Electron Microscopy). The APEX-II adopted a two-cell cavity design with resonant frequency of 162.5 MHz. The APEX-II gun is targeting to achieve exceeding 30 MV/m of launch gradient at the cathode and output energy above 1.5 MeV with transverse emittance of 0.1 um at 100 pC. Advanced MOGA optimization technique has been used for both the RF cavity design and extensive beam dynamics studies using APEX-like and LCLS-II like injector layout. Detailed RF designs, beam dynamics studies, preliminary engineering design and FEA analysis will be presented, with cavity features that were demonstrated to be crucial in the operation of the APEX gun. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1891 EP - 1894 KW - cavity KW - gun KW - electron KW - cathode KW - brightness DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPRB097 UR - http://jacow.org/ipac2019/papers/tuprb097.pdf ER - TY - CONF AU - Huang, P.W. AU - Chen, Y. AU - Filippetto, D. AU - Good, J.D. AU - Groß, M. AU - Isaev, I.I. AU - Koschitzki, C. AU - Krasilnikov, M. AU - Lal, S. AU - Li, X. AU - Lishilin, O. AU - Melkumyan, D. AU - Niemczyk, R. AU - Oppelt, A. AU - Qian, H.J. AU - Sannibale, F. AU - Shaker, H. AU - Stephan, F. AU - Tang, C.-X. AU - Vashchenko, G. AU - Wan, W. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 1964 EP - 1967 KW - cathode KW - solenoid KW - emittance KW - electron KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS014 UR - http://jacow.org/ipac2019/papers/tupts014.pdf ER - TY - CONF AU - Zheng, L.M. AU - Chen, H. AU - Du, Y.C. AU - Gao, B. AU - Huang, W.-H. AU - Li, R.K. AU - Li, Z.Z. AU - Tang, C.-X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Design of a 217 MHz VHF Gun at Tsinghua University J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A 217 MHz VHF gun operating in CW mode is designing at Tsinghua University. The cathode gradient is designed to be 30 MV/m to accelerate the electron bunches up to 878 keV. The cavity profile is optimized in CST to minimize the input power, peak surface electric field, and peak wall power density. The multipacting analysis and the thermal analysis are also presented in this paper. Further gun shape optimization and mechanical design are ongoing. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2050 EP - 2053 KW - gun KW - cathode KW - electron KW - cavity KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS053 UR - http://jacow.org/ipac2019/papers/tupts053.pdf ER - TY - CONF AU - Luo, T.H. AU - Feng, H.Q. AU - Filippetto, D. AU - Johnson, M.J. AU - Lambert, A.R. AU - Li, D. AU - Mitchell, C.E. AU - Sannibale, F. AU - Staples, J.W. AU - Virostek, S.P. AU - Wells, R.P. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - RF Design of APEX2 Cavities J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - APEX2 is a proposed high repetition rate, high brightness electron source based on CW normal conducting RF cavities, aiming to further extend the brightness performance for FEL and UED/UEM beyond APEX. APEX2 consists of two cavities, one gun cavity for generating photo-electrons and one following cavity for beam energy boosting. In this paper, we present the RF design of the APEX2 cavities. The design has considered both beam dynamics requirements and engineering feasibility. A novel geometry optimization method with Genetic Algorithm has been implemented in the design procedure. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2094 EP - 2097 KW - gun KW - cavity KW - cathode KW - electron KW - brightness DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-TUPTS076 UR - http://jacow.org/ipac2019/papers/tupts076.pdf ER - TY - CONF AU - Wang, M.W. AU - Guan, X. AU - Ma, P.F. AU - Qiu, M.T. AU - Wang, D. AU - Wang, X.W. AU - Wang, Z.M. AU - Zheng, S.X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - A Rotation Method to Calibrate BPM Electric Offsets J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Beam position monitor is a key instrument for machine commissioning. To measure beam position accurately, offline calibrations to acquire the sensitivity and offsets of the BPM are essential prerequisites. A new method to calibrate the BPM electric offset is proposed in this paper. By measuring the location variation of the BPM electric center after rotatingtheBPM180degrees, theBPMoffsetcanbederived. The method is more convenient, universal and accurate than the traditional methods. The method is successfully applied to calibrate the button BPM of Xi’an Proton Application Facility. The repetitive measurement error is 20.8 um. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2595 EP - 2597 KW - laser KW - site KW - radiation KW - instrumentation KW - proton DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPGW052 UR - http://jacow.org/ipac2019/papers/wepgw052.pdf ER - TY - CONF AU - Lei, Y. AU - Du, C.T. AU - Guan, X. AU - Tang, R. AU - Wang, X.W. AU - Xing, Q.Z. AU - Zheng, S.X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Tuning of a Tapered Ridge-Loaded Waveguide Coupler for a Drift Tube LINAC of the Compact Pulsed Hadron Source J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - This paper presents the tuning result of a tapered ridge-loaded waveguide coupler for the drift tube linac (DTL) of the compact pulsed hadron source (CPHS) at Tsinghua University. The coupler has been designed, manufactured, and mounted on the DTL cavity for the cold measurement and tuning. The iris diameter of the coupler which is related to the coupling coefficient needs to be determined in the tuning experiment, due to the difference between the designed and measured quality factors. Meanwhile, we found that the relationship between the coupling coefficient and iris diameter from the traditional analytical design method is not applicable when the iris diameter is relatively large. In this paper, the target coupling coeffi-cient is analysed, and the limit of the original analytical design is presented. The measurement method is intro-duced to improve the measurement efficiency and the tuning process of the coupling coefficient to the target value is described. After several iterations, the coupling coefficient is tuned to 1.54 which is close to the desired value of 1.56. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2893 EP - 2895 KW - GUI KW - coupling KW - DTL KW - linac KW - target DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB039 UR - http://jacow.org/ipac2019/papers/weprb039.pdf ER - TY - CONF AU - Liu, J.Y. AU - Chen, H.B. AU - Grudiev, A. AU - Shi, J. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Wakefield Suppression in the Main LINAC of the Klystron-Based First Stage of CLIC at 380 GeV J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - An alternative klystron-based scenario for the first stage of Compact Linear Collider (CLIC) at 380 GeV centre-of-mass energy was proposed. To preserve the beam stability and luminosity of CLIC, the beam-induced transverse long-range wakefield in main linac must be suppressed to an acceptable value. The design of klystron-based accelerating structure is based on waveguide damping structure (WDS). The high-order modes (HOMs) propagating into four waveguides are absorbed by HOM damping loads. In this paper, the wakefield suppression in CLIC-K based on GdfidL code simulations are presented. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2899 EP - 2902 KW - wakefield KW - HOM KW - GUI KW - damping KW - linac DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB043 UR - http://jacow.org/ipac2019/papers/weprb043.pdf ER - TY - CONF AU - Peng, M.M. AU - Jiang, Y.L. AU - Liu, J.Y. AU - Liu, Z.N. AU - Meng, X.C. AU - Shi, J. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - High-Power Test of a 12 Cell Accelerating Structure Build in Halves J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - An X-band 12 cell travelling-wave accelerating structure has been developed and high-power tested at Tsinghua University in China. This structure works at 2⁄3 π at the frequency of 11.424 GHz. It is a 12-cell constant-impedance structure build in halves and was silver-brazed as a vacuum tight structure. The high power test was conducted at Tsinghua X-band high power test facility [1] with a 50-MW X-band klystron at a repetition rate to 40 Hz. The final input power was 51.23 MW with a 200 ns pulse width, which means an accelerating gradient of 88.58 MV/m was reached. This paper presents the high power test results including the gradient and breakdown history. PB - JACoW Publishing CP - Geneva, Switzerland SP - 2912 EP - 2914 KW - klystron KW - vacuum KW - shielding KW - GUI KW - ECR DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB047 UR - http://jacow.org/ipac2019/papers/weprb047.pdf ER - TY - CONF AU - Feng, H.Q. AU - Baptiste, K.M. AU - Huang, W.-H. AU - Li, D. AU - Liu, Z.N. AU - Luo, T.H. AU - Tang, C.-X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Optimization of RF Cavities Using MOGA for ALS-U J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A multi-objective genetic algorithm-based optimiza-tion process has been applied to optimize the RF design of a 500 MHz main cavity and a 1.5 GHz Higher Harmon-ic Cavity (HHC) for the Advanced Light Source upgrade (ALS-U) in Lawrence Berkeley National Laboratory (LBNL). For the main cavity, a significant improvement, compared with the existing ALS cavity, has been achieved in cavity shunt impedance and power loss den-sity simultaneously. The field strengths and distribution of the optimized structure are analysed for further re-search. For the HHC, a cavity with low R/Q has been pre-liminary designed to mitigate the beam instability. This study also serves as an example of how a genetic algo-rithm can be used for optimizing RF cavities. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3007 EP - 3010 KW - cavity KW - impedance KW - simulation KW - controls KW - gun DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB080 UR - http://jacow.org/ipac2019/papers/weprb080.pdf ER - TY - CONF AU - Feng, H.Q. AU - Baptiste, K.M. AU - De Santis, S. AU - Huang, W.-H. AU - Li, D. AU - Liu, Z.N. AU - Luo, T.H. AU - Tang, C.-X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Design Study on Higher Harmonic Cavity for ALS-U J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The ALS upgrade (ALS-U) to a diffraction-limited light source [1] depends on the ability to lengthen the stored bunches to limit the emittance growth and increase the beam life time. Higher harmonic cavities (HHCs), also known as Landau cavities, have been proposed to in-crease beam lifetime and Landau damping by lengthen-ing the bunch. We present an optimized 1.5 GHz normal conducting HHC design for the ALS-U with a supercon-ducting-like geometry using multi-objective genetic algorithm (MOGA) for lower R/Q. The optimization goal is to reach the required shunt impedance while maintain-ing a relatively high Q value of the cavities. To minimize the coupled bunch instabilities, higher-order mode (HOM) of the HHC as well as corresponding impedance are explored and characterized. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3011 EP - 3013 KW - cavity KW - impedance KW - higher-order-mode KW - simulation KW - wakefield DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPRB081 UR - http://jacow.org/ipac2019/papers/weprb081.pdf ER - TY - CONF AU - Deng, X.J. AU - Chao, A. AU - Huang, W.-H. AU - Tang, C.-X. AU - Zhang, Y. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Transverse-Longitudinal Coupling for Harmonic Generation and Bunch Length Manipulation J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A general harmonic generation and bunch length manipulation scheme using transverse-longitudinal coupling is presented. The method makes use of the freedom in projecting the three beam eigen-emittances into different physical dimensions. A realization of this coupling lattice, a PEHG variant, is given as an example. For the purpose of harmonic generation and bunch compression, this method is advantageous when the transverse emittance is small. The combination with sawtooth waveform modulation is proposed to boost the bunching further. Transverse-longitudinal coupling in storage rings are briefly discussed. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3160 EP - 3163 KW - emittance KW - bunching KW - coupling KW - lattice KW - storage-ring DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS028 UR - http://jacow.org/ipac2019/papers/wepts028.pdf ER - TY - CONF AU - Yao, H.J. AU - Guan, X. AU - Li, G.R. AU - Ma, P.F. AU - Wang, X.W. AU - Zhang, Q. AU - Zheng, S.X. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - A High-performance Code for Beam Dynamics Simulation of Synchrotrons J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - This paper introduces a high-performance code Li-track for beam dynamics simulation of synchrotrons. It is a parallel multi-particle tracking program written entirely in C++ and therefore has a high computational speed. The overall design of Li-track is based on object-oriented mode, and the implemented element model can be easily reused to build different synchrotron lattice. The symplectic integral algorithm is used to ensure there are no physical errors in a long-term simulation. This code has been used for the slow extraction simulation of XiPAF synchrotron and the results will be given in this paper. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3170 EP - 3173 KW - simulation KW - extraction KW - synchrotron KW - sextupole KW - proton DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS033 UR - http://jacow.org/ipac2019/papers/wepts033.pdf ER - TY - CONF AU - Dong, Z. AU - Chen, H. AU - Deng, X.J. AU - Du, Y.C. AU - Zhou, Z. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Generation of Sub-Femtosecond Electron Beams and Electron Bunch Trains With High Form Factor Using Wake Field Structures J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - In this paper, we propose two beam manipulation methods with wakefield structures in a photo-injector. First, we propose a simple scheme to compensate non-linear effects during ballistic bunching by using a wakefield structure. Simulations have shown beams of 1 pC charge can be compressed to 1.56 fs rms, and even shorter beams (a few hundred attoseconds) can be obtained with bunch charge well below 1 pC. In the second part, a method of producing bunch trains with high form factor is proposed by using multiple wake-field structures. Simulation results have shown the production of a train with a form factor of 0.5 using a 1 nC beam at few-MeV energy. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3174 EP - 3176 KW - electron KW - wakefield KW - bunching KW - space-charge KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-WEPTS034 UR - http://jacow.org/ipac2019/papers/wepts034.pdf ER - TY - CONF AU - Zhou, Z. AU - Du, Y.-C. AU - Huang, W.-H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Single-Shot Cascade High Energy Electron Radiography based on Strong Permanent Magnet Quadrupole Composed Imaging Lens J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - High energy electron imaging, an extension of conventional transmission electron microscopy, is suitable for imaging of thicker objects and expected to be a promising tool for diagnostics of high energy density physics (HEDP). A cascade high energy electron imaging system using two-stage imaging lenses based on strong permanent magnet quadrupoles is designed, optimized and finally installed at Tsinghua university. Encouraging result of 1.6-μm space resolution is obtained in our primary experiments, along with the clear imaging of a spherical capsule as a substitute of the targets used in inertial confinement fusion. Successful implement of cascade high energy electron imaging system is necessary for reaching better resolving power of the imaging system, and well matching of design, simulation with experimental results paves the way to high energy electron microscopy to provide full capacities for diagnostics of HEDP with sub-um and picosecond spatiotemporal resolutions. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3491 EP - 3493 KW - electron KW - experiment KW - simulation KW - quadrupole KW - optics DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPMP020 UR - http://jacow.org/ipac2019/papers/thpmp020.pdf ER - TY - CONF AU - Weikum, M.K. AU - Akhter, T. AU - Alesini, D. AU - Alexandrova, A.S. AU - Anania, M.P. AU - Andreev, N.E. AU - Andriyash, I.A. AU - Aschikhin, A. AU - Audet, T. AU - Aßmann, R.W. AU - Bacci, A. AU - Barna, I.F. AU - Beaton, A. AU - Beck, A. AU - Beluze, A. AU - Bernhard, A. AU - Bielawski, S. AU - Bisesto, F.G. AU - Brandi, F. AU - Brinkmann, R. AU - Bründermann, E. AU - Bussmann, M.H. AU - Bussolino, G. AU - Büscher, M. AU - Chancé, A. AU - Chen, M. AU - Chiadroni, E. AU - Cianchi, A. AU - Clarke, J.A. AU - Cole, J. AU - Couprie, M.-E. AU - Croia, M. AU - Cros, B. AU - Crump, P.A. AU - Dattoli, G. AU - De Nicola, S. AU - Del Dotto, A. AU - Delerue, N. AU - Dias, J.M. AU - Dorda, U. AU - Fedele, R. AU - Ferran Pousa, A. AU - Ferrario, M. AU - Filippi, F. AU - Fiore, G. AU - Fonseca, R.A. AU - Galimberti, M. AU - Gallo, A. AU - Ghaith, A. AU - Giove, D. AU - Giribono, A. AU - Gizzi, L.A. AU - Grüner, F.J. AU - Habib, A.F. AU - Haefner, C. AU - Heinemann, T. AU - Hidding, B. AU - Holzer, B.J. AU - Hooker, S.M. AU - Hosokai, T. AU - Huebner, M. AU - Irman, A. AU - Jafarinia, F. AU - Jaroszynski, D.A. AU - Joshi, C. AU - Kaluza, M. AU - Kando, M. AU - Karger, O.S. AU - Karsch, S. AU - Khazanov, E. AU - Khikhlukha, D. AU - Knetsch, A. AU - Kocon, D. AU - Koester, P. AU - Kononenko, O.S. AU - Korn, G. AU - Kostyukov, I. AU - Kruchinin, K.O. AU - Labate, L. AU - Le Blanc, C. AU - Lechner, C. AU - Leemans, W. AU - Lehrach, A. AU - Li, X. AU - Libov, V. AU - Lifschitz, A. AU - Litvinenko, V. AU - Lu, W. AU - Lundh, O. AU - Maier, A.R. AU - Malka, V. AU - Manahan, G.G. AU - Mangles, S.P.D. AU - Marchetti, B. AU - Martinez de la Ossa, A. AU - Martins, J.L. AU - Mason, P.D. AU - Massimo, F. AU - Mathieu, F. AU - Maynard, G. AU - Mazzotta, Z. AU - Molodozhentsev, A.Y. AU - Mostacci, A. AU - Murphy, C.D. AU - Müller, A.-S. AU - Najmudin, Z. AU - Nghiem, P.A.P. AU - Nguyen, F. AU - Niknejadi, P. AU - Osterhoff, J. AU - Oumbarek Espinos, D. AU - Papadopoulos, D.N. AU - Patrizi, B. AU - Pattathil, R. AU - Petrillo, V. AU - Pocsai, M.A. AU - Poder, K. AU - Pompili, R. AU - Pribyl, L. AU - Pugacheva, D. AU - Romeo, S. AU - Rossetti Conti, M. AU - Rossi, A.R. AU - Rossmanith, R. AU - Roussel, E. AU - Sahai, A.A. AU - Sarri, G. AU - Schaper, L. AU - Scherkl, P. AU - Schramm, U. AU - Schroeder, C.B. AU - Scifo, J. AU - Serafini, L. AU - Sheng, Z.M. AU - Siders, C. AU - Silva, L.O. AU - Silva, T. AU - Simon, C. AU - Sinha, U. AU - Specka, A. AU - Streeter, M.J.V. AU - Svystun, E.N. AU - Symes, D. AU - Szwaj, C. AU - Tauscher, G.E. AU - Terzani, D. AU - Thompson, N. AU - Toci, G. AU - Tomassini, P. AU - Torres, R. AU - Ullmann, D. AU - Vaccarezza, C. AU - Vannini, M. AU - Vieira, J.M. AU - Villa, F. AU - Wahlstrom, C.-G. AU - Walczak, R. AU - Walker, P.A. AU - Wang, K. AU - Welsch, C.P. AU - Wiggins, S.M. AU - Wolfenden, J. AU - Xia, G.X. AU - Yabashi, M. AU - Zhu, J. AU - Zigler, A. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Status of the Horizon 2020 EuPRAXIA Conceptual Design Study J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The Horizon 2020 Project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is producing a conceptual design report for a highly compact and cost-effective European facility with multi-GeV electron beams accelerated using plasmas. EuPRAXIA will be set up as a distributed Open Innovation platform with two construction sites, one with a focus on beam-driven plasma acceleration (PWFA) and another site with a focus on laser-driven plasma acceleration (LWFA). User areas at both sites will provide access to FEL pilot experiments, positron generation and acceleration, compact radiation sources, and test beams for HEP detector development. Support centres in four different countries will complement the pan-European implementation of this infrastructure. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3638 EP - 3642 KW - plasma KW - laser KW - electron KW - acceleration KW - site DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPGW026 UR - http://jacow.org/ipac2019/papers/thpgw026.pdf ER - TY - CONF AU - Zhang, J. AU - He, Y.X. AU - Hua, J.F. AU - Liu, D.X. AU - Lu, W. AU - Ma, Y. AU - Nie, Z. AU - Pai, C.H. AU - Su, Q. AU - Wu, Y.P. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Temporal Characterization of Electron Bunches From Self-Injection and Ionization Injection in a Laser Wakefield Accelerator J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - Plasma based accelerators (PBAs) have a proven capability to generate high energy electron beams with ultrashort duration (~ 10 fs) and high peak current (~ 10 kA), which opens the opportunity for compact free electron lasers. To meet the requirements of such challenging applications, controllable injection is highly needed to produce high-quality and highly stable electron beams. As we know, the beam parameters，including the current profile, strongly depend on the injection process. To explore the underlying physics and optimize beam parameters in PBAs, a temporal characterization is highly required for different injection schemes. Based on coherent transition radiation(CTR) method, the preliminary experiment to measure beam temporal profiles from both self-injection and ionization injection schemes in a single-shot mode has been performed at Tsinghua University. And the simulations using the similar experimental parameters have been performed to interpret the different injection processes, which show some agreement with the experimental results, especially for the features of bunch durations PB - JACoW Publishing CP - Geneva, Switzerland SP - 3693 EP - 3696 KW - injection KW - electron KW - laser KW - plasma KW - radiation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPGW048 UR - http://jacow.org/ipac2019/papers/thpgw048.pdf ER - TY - CONF AU - Lin, Z.Y. AU - Du, Y.-C. AU - Huang, G. AU - Huang, W.-H. AU - Sun, Z. AU - Tang, C.-X. AU - Tang, J. AU - Xu, Y.L. AU - Zhang, D. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - A Novel Microwave Switch-Based LLRF System for Long-Term System Phase Drift Calibration J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The long-term phase drift is one of the important issue for the stability of the Low level RF system. The signal crosstalk and temperature effect on the RF field detectors will significantly limited the performance of the phase detecting precise and the phase locking. A novel micro-wave switch-based LLRF system has been developed in Tsinghua accelerator lab. The microwave switch are ap-plied to in the chopper circuit to turn continuous signal into pulse signal in the time domain to avoid the mutual signal interference. In this paper the LLRF system based on microwave switch is present. The preliminary long-term experiments result shows the phase stability can achieve about 50fs RMS slow drift; and the peak-to-peak value of the slow drift was (~2°C p-p) over 4 days. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3915 EP - 3917 KW - LLRF KW - controls KW - coupling KW - ISOL KW - experiment DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPRB045 UR - http://jacow.org/ipac2019/papers/thprb045.pdf ER - TY - CONF AU - Lin, Z.Y. AU - Du, Y.-C. AU - Huang, G. AU - Huang, W.-H. AU - Sun, Z. AU - Tang, C.-X. AU - Tang, J. AU - Xu, Y.L. AU - Zhang, D. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - The Preliminary Long-Term Slow Drift Calibration Study in Low-Level Rf System J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The phase drift of the RF signal in the low-level radio frequency (LLRF) system is observed in the long-term operation, which limits the performance and stability of the LLRF system. The long-term drift was reproduced in the lab. Its effect and sources of error were explored in the simple LLRF46 board and the simplest LLRF system. It is founded that the temperature will significantly lead to the phase distortion of the two signal channels, although with the same electron device. The distortion will finally cause the long-term drift with temperature floating. A fixed phase calibration signal (CAL signal) is applied to deal with the signal channels difference. The preliminary tests were conducted and the results were analysed. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3918 EP - 3920 KW - LLRF KW - experiment KW - monitoring KW - timing KW - controls DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPRB046 UR - http://jacow.org/ipac2019/papers/thprb046.pdf ER - TY - CONF AU - Wang, Z.H. AU - Liu, Z.N. AU - Shi, J. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - DAMAGE BEHAVIOR OF TUNGSTEN TARGETS FOR 6 MEV LINEAR ACCELERATORS J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The target in electron linear accelerator is subjected to high-frequency and intense thermal shocks. Elevated temperatures in the target may lead to target recrystallization, fatigue cracking, creep and vaporization. In this study, experiments were carried out to investigate the damage behaviour of tungsten targets in 6 MeV linear accelerators under pulsed electron beam. The results show that recrystallization occurs after loading 6 MeV electron beam with repetition frequency of 220 Hz, pulse width of 4μs and mean current of 151μA for 248 s. Deformation and cracking caused by recrystallization are observed on the surface of the target. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3934 EP - 3936 KW - target KW - experiment KW - electron KW - ECR KW - controls DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPRB055 UR - http://jacow.org/ipac2019/papers/thprb055.pdf ER - TY - CONF AU - Wang, Z.H. AU - Liu, J.Y. AU - Shi, J. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - Dose Measurement Experiments for Single and Composite Targets in 6 Mev Linear Accelerators J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - The target in electron linear accelerator plays an im-portant role in the production of photon. Targets of different materials and thicknesses have different X-ray yields. In this study, experiments were carried out to measure the dose rates of single targets and composite targets of different thicknesses for 6 MeV linear accel-erators utilizing ionization chamber. The electron ener-gy spectrum at the outlet of accelerating tube was de-tected with magnetic analyser. The experimental results show consistent rules with Monte Carlo simulations. Composite material target of 1.2 mm tungsten and 2 mm copper can deliver 1242 rad/min/100uA dose rate at 1 meter in front of the target. Dose rates of tungsten- rhenium alloy(74%W-26%rhenium) targets were exam-ined too. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3937 EP - 3939 KW - target KW - site KW - electron KW - experiment KW - simulation DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPRB056 UR - http://jacow.org/ipac2019/papers/thprb056.pdf ER - TY - CONF AU - Liu, Z.N. AU - Chen, H.B. AU - Shi, J. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - There-Dimensional Simulation of a C-Band 32-Beam Klystron J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - A 32-beam klystron working at 5.712 GHz has been designed with efficiency of 70% and output power of 3.4 MW. Core oscillations method (COM) is chosen to bunch electrons. The code KlyC is used for 1-D and 1.5-D calculation and a series of parameters are given after optimizing, including the position, frequency, R/Q, Q₀ and Qe of cavities. CST/PIC is used to make the final design and coaxial cavities are used. This paper describes 1-D, 1.5-D and 3-D beam dynamics of the klystron, compares their differences, and analyses effect of these differences on efficiency. PB - JACoW Publishing CP - Geneva, Switzerland SP - 4190 EP - 4193 KW - klystron KW - electron KW - cavity KW - simulation KW - bunching DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPTS038 UR - http://jacow.org/ipac2019/papers/thpts038.pdf ER - TY - CONF AU - Liu, F. AU - Chen, H.B. AU - Liu, J.Y. AU - Liu, Z.N. AU - Shi, J. AU - Zha, H. ED - Boland, Mark ED - Tanaka, Hitoshi ED - Button, David ED - Dowd, Rohan ED - Schaa, Volker RW ED - Tan, Eugene TI - DESIGN OF A COMPACT VARIABLE X-BAND RF POWER SPLITTER J2 - Proc. of IPAC2019, Melbourne, Australia, 19-24 May 2019 CY - Melbourne, Australia T2 - International Particle Accelerator Conference T3 - 10 LA - english AB - This paper presents a design of a compact variable X-band RF power splitter. The RF power splitter includes one input port and two output ports, and the power divi-sion ratio can be adjusted by changing the position of a short circuit piston. This system keeps a good match (less than -40 dB) at any power division ratio. An E-bend waveguide structure is selected to make the geometry more compact (11cm in length, 3.5cm in width and 5 cm in height). Special studies was conducted to sustain a low surface electrical field (maximum 65 MV/m at 100 MW input), and large bandwidth (250MHz). This power split-ter is designed for high-power test stand at Tsinghua Uni-versity. PB - JACoW Publishing CP - Geneva, Switzerland SP - 4194 EP - 4196 KW - GUI KW - impedance KW - klystron KW - electron KW - network DA - 2019/06 PY - 2019 SN - 978-3-95450-208-0 DO - DOI: 10.18429/JACoW-IPAC2019-THPTS039 UR - http://jacow.org/ipac2019/papers/thpts039.pdf ER -