Keyword: bunching
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MOPB021 Bunch-by-bunch Phase Modulation for Linac Beam-loading Compensation beam-loading, linac, impedance, injection 216
  • G. Huang, D. Jia, K. Jin, H. Lin, Weishi, Zhou. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y. Liu
    USTC, Hefei, Anhui, People's Republic of China
  Funding: supported by NSFC-CAS Joint Fund, contract no. 11079034
If the linac is loaded by a high current, long pulse multi-bunch beam, the energy of the beam drops with time during the pulse. The bunch phase modulation method is introduced to compensate the beam loading. In this method the beam phase in the RF accelerating filed is changed bunch-by-bunch, the beam energy gain in the RF filed gradually grows up, which cancels the drop due to beam loading. The relationship between the beam phase distribution and the linac parameters is calculated in this paper.
MOPB035 The Linear Accelerating Structure Development for HLS Upgrade cavity, linac, electron, injection 252
  • K. Jin, Y. Hong, G. Huang, D. Jia, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Hefei Light Source (HLS) is mainly composed of an 800 MeV electron storage ring and a 200 MeV constant-impedance Linac functioning as its injector. A new Linac is developed in view of the Full Energy Injection and the Top-up Injection scheme will be adopted in the HLS upgrade. In this paper, an 800 MeV linear accelerating system construction, the constant-gradient structure design and the symmetry couplers consideration will be described in detail. The manufacture technology, the RF measurement, the high power test results and the accelerating system operation are presented.  
MOPB049 Design of Compact C-Band Standing-Wave Accelerator for Medical Radiotherapy electron, coupling, focusing, cavity 285
  • H. Yang, M.-H. Cho, W. Namkung
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S.H. Kim
    ANL, Argonne, USA
  • J.-S. Oh
    NFRI, Daejon, Republic of Korea
  Funding: Work supported by POSTECH Physics BK21 Program.
We design a C-band standing-wave accelerator for an X-ray and electron source of medical radiotherapy. The accelerator system is operated two modes, using the X-ray and electron beams. Since two modes require different energy, the accelerator is capable of producing 6-MeV, 100-mA pulsed electron beams with peak 2-MW RF power, and 7.5-MeV, 50 mA electron beams with peak 2.5-MW RF power. The beam is focused by less than 1 mm without external magnets. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists of 3 bunching cells, 14 normal cells and a coupling cell. It is operated with the π/2-mode standing-wave. The bunching cells are designed to enhance the RF phase focusing. Each cavity is designed by the MWS code within 3% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics.
THPB025 325 MHz CW Room Temperature High Power Bunching Cavity for the China ADS MEBT1 cavity, impedance, vacuum, resonance 903
  • S. Pei, X. Li, H.F. Ouyang, J.R. Zhang
    IHEP, Beijing, People's Republic of China
  Two room temperature high power bunching cavities are required to be located in the ADS MEBT1 section. Double re–entrant nose cone geometry has been adopted as the type of the bunching cavity for its simplicity, higher shunt impedance and lower risk of multipacting. SUPERFISH is used to optimize the internal dimensions of the bunching cavity, then the RF–thermal–structural–RF coupled analysis were carried out in ANSYS to obtain the preliminary mechanical design, the layout of the cooling channels is optimized to suppress the frequency shift as much as possible. The cavity was specially designed to have the capability to withstand the 1 atm air pressure effect. In addition, the main dimensions of the coupler and tuner are also estimated.