IPAC2011 - List of Authors (Shi, J.)

Paper	Title	Page
MOPC012	Fabrication of the CERN/PSI/ST X-band Accelerating Structures	86
	M.M. Dehler, A. Citterio, R. Zennaro PSI, Villigen, Switzerland S. Atieh, D. Gudkov, S. Lebet, G. Riddone, J. Shi CERN, Geneva, Switzerland G. D'Auria, C. Serpico ELETTRA, Basovizza, Italy
	Within a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a multi- purpose X-band accelerating structure has been designed and fabricated, used for high gradients tests in the CLIC structure testing program and in the FEL projects of PSI and ST. The structure has 72 cells with a phase advance of 5 pi/6 and includes upstream and downstream wakefield monitors to measure the beam alignment. The SLAC mode launcher design is used to feed it with RF power. Following the CERN fabrication procedures for high-gradient structure, diffusion bonding and brazing in hydrogen atmosphere is used to assemble the cells. After tuning, a vacuum bakeout is required before the feedthroughs for the wake field monitors are welded in as a last step. We describe the experiences gained in finishing the first two structures out of a series of four and present the results from the RF tuning and low level RF tests.

MOPC021	Design of a Choke-mode Damped Accelerating Structure for CLIC Main Linac	113
	J. Shi, A. Grudiev, W. Wuensch CERN, Geneva, Switzerland H. Chen, W.-H. Huang, C.-X. Tang, H. Zha TUB, Beijing, People's Republic of China
	Choke-mode damped accelerating structures are being studied as an alternative to the CLIC baseline structure by a CERN-Tsinghua collaboration. Choke-mode structures hold the potential for much lower levels of pulsed surface heating and, since milling is not needed, reduced cost. Structures with radial choke attached are simulated in Gdfidl to investigate the damping of the transverse wake. The first pass-band of the dipole modes is well damped, while the higher order dipole modes are possible to be reflected by the choke. Therefore, the geometry of the choke is tuned to minimize the reflection of these higher order dipoles. Based on this damping scheme, an accelerating structure with the same iris dimensions as the nominal CLIC design but with choke-mode damping has been designed. A prototype structure will be manufactured and high power tested in the near future.

THPS044	Study of Charge Exchange Injection in HITFiL	3520
	W.P. Chai, J. Shi, J.W. Xia, J.C. Yang IMP, Lanzhou, People's Republic of China
	A new accelerator complex dedicated to hadron cancer therapy, Heavy-Ion Therapy Facility in Lanzhou (HITFiL), is proposed and designed. Based on the operating experience and existing technology on HIRFL-CSR, a heavy-ion cyclotron is used as an injector instead of a linac. A heavy-ion synchrotron as main component is designed with special attention paid to compact structure, high reliability and low cost. HITFiL is designed to accommodate both proton and carbon-ion using the same injecting channel but different injecting points. Charge exchange injection scheme, which is more efficient compared with single-turn injection but less costly compared with multiple multi-turn injection aided by electron-cooling, is adopted. H²⁺ or C⁵⁺ beams, pre-accelerated by the cyclotron, are stripped into H⁺ or C⁶⁺ by a carbon foil at injection point, then injected and merged into synchrotron coasting orbit. The design of the injection system is presented in this paper. The whole injection process is simulated, optimization of parameters on injecting efficiency, painting scheme and emittance growth are performed. The resulting beam distribution in phase space after injection is achieved.

Paper

Title

Page

Fabrication of the CERN/PSI/ST X-band Accelerating Structures

86

M.M. Dehler, A. Citterio, R. Zennaro
PSI, Villigen, Switzerland
S. Atieh, D. Gudkov, S. Lebet, G. Riddone, J. Shi
CERN, Geneva, Switzerland
G. D'Auria, C. Serpico
ELETTRA, Basovizza, Italy

Within a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a multi- purpose X-band accelerating structure has been designed and fabricated, used for high gradients tests in the CLIC structure testing program and in the FEL projects of PSI and ST. The structure has 72 cells with a phase advance of 5 pi/6 and includes upstream and downstream wakefield monitors to measure the beam alignment. The SLAC mode launcher design is used to feed it with RF power. Following the CERN fabrication procedures for high-gradient structure, diffusion bonding and brazing in hydrogen atmosphere is used to assemble the cells. After tuning, a vacuum bakeout is required before the feedthroughs for the wake field monitors are welded in as a last step. We describe the experiences gained in finishing the first two structures out of a series of four and present the results from the RF tuning and low level RF tests.

MOPC021

Design of a Choke-mode Damped Accelerating Structure for CLIC Main Linac

113

J. Shi, A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
H. Chen, W.-H. Huang, C.-X. Tang, H. Zha
TUB, Beijing, People's Republic of China

Choke-mode damped accelerating structures are being studied as an alternative to the CLIC baseline structure by a CERN-Tsinghua collaboration. Choke-mode structures hold the potential for much lower levels of pulsed surface heating and, since milling is not needed, reduced cost. Structures with radial choke attached are simulated in Gdfidl to investigate the damping of the transverse wake. The first pass-band of the dipole modes is well damped, while the higher order dipole modes are possible to be reflected by the choke. Therefore, the geometry of the choke is tuned to minimize the reflection of these higher order dipoles. Based on this damping scheme, an accelerating structure with the same iris dimensions as the nominal CLIC design but with choke-mode damping has been designed. A prototype structure will be manufactured and high power tested in the near future.

THPS044

Study of Charge Exchange Injection in HITFiL

3520

W.P. Chai, J. Shi, J.W. Xia, J.C. Yang
IMP, Lanzhou, People's Republic of China

A new accelerator complex dedicated to hadron cancer therapy, Heavy-Ion Therapy Facility in Lanzhou (HITFiL), is proposed and designed. Based on the operating experience and existing technology on HIRFL-CSR, a heavy-ion cyclotron is used as an injector instead of a linac. A heavy-ion synchrotron as main component is designed with special attention paid to compact structure, high reliability and low cost. HITFiL is designed to accommodate both proton and carbon-ion using the same injecting channel but different injecting points. Charge exchange injection scheme, which is more efficient compared with single-turn injection but less costly compared with multiple multi-turn injection aided by electron-cooling, is adopted. H²⁺ or C⁵⁺ beams, pre-accelerated by the cyclotron, are stripped into H⁺ or C⁶⁺ by a carbon foil at injection point, then injected and merged into synchrotron coasting orbit. The design of the injection system is presented in this paper. The whole injection process is simulated, optimization of parameters on injecting efficiency, painting scheme and emittance growth are performed. The resulting beam distribution in phase space after injection is achieved.