IPAC2011 - List of Authors (Chen, H.)

Paper

Title

Page

Status and Challenges of the China Spallation Neutron Source

889

S. Fu, H. Chen, Y.W. Chen, Y.L. Chi, H. Dong, L. Dong, S.X. Fang, K.X. Huang, W. Kang, J. Li, L. Ma, H.F. Ouyang, H. Qu, H. Sun, J. Tang, C.H. Wang, Q.B. Wang, S. Wang, T.G. Xu, Z.X. Xu, X. Yin, C. Zhang, J. Zhang
IHEP Beijing, Beijing, People's Republic of China

The accelerator complex of China Spallation Neutron Source (CSNS) mainly consists of an H⁻ linac of 80 MeV and a rapid-cycling synchrotron of 1.6 GeV. It operates at 25 Hz repetition rate with an initial proton beam power of 100 kW and is upgradeable to 500kW. The project will start construction in the middle of 2011 with a construction period of 6.5 years. The CSNS accelerator is the first large-scale, high-power accelerator project to be constructed in China and thus we are facing a lot of challenges. This paper presents the current status of CSNS project and summarizes the technology development during the past several years.

Slides TUXA01 [3.444 MB]

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.

MOPC022

Development of a Compact C-band Photocathode RF Gun

116

X.H. Liu, H. Chen, W.-H. Huang, H.J. Qian, C.-X. Tang, Z. Zhang
TUB, Beijing, People's Republic of China

Funding: This work is supported by National Natural Science Foundation of China and National Basic Research Program of China (973 Program).
A C-band photocathode RF gun for a compact electron diffraction facility is developed in Tsinghua University, which is designed to work at the frequency of 5.712GHz. This paper presents the physics and structure design of this C-band RF gun, and the comparison on beam dynamics of S-band and C-band photoinjector has been done. Some new structure design will be adopted in this gun, including the optimized cavity length and elliptical iris, which is helpful to achieve lower emittance and larger mode separation.

MOPC023

Design of a C-band 6 MeV Standing-wave Linear Accelerating Structure

119

J.H. Shao, H. Chen, Q.Z. Xing
TUB, Beijing, People's Republic of China

We design a C-band standing-wave biperiodic on-axis coupled linear accelerating structure for industrial and medical applications. It’s less than 300mm long; consists of 3 bunching cells and 9 normal cells. It can accelerate electrons to 6MeV and the pulsed beam current is 100mA. The RF power source is a 2.5MW magnetron. We implement 2D cells geometry optimization by SUPERFISH, beam dynamics study by PARMELA and full scale 3D calculations by MAFIA codes.

TUPC110

Ultrashort Bunch Train Longitudinal Diagnostics using RF Deflecting Structure

1275

Y. Yang, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, L.X. Yan
TUB, Beijing, People's Republic of China

Ultrashort electron bunch train has been produced using UV laser stacking in Tsinghua University. With an S-band deflecting cavity inserted into the Tsinghua Thomson Scattering beamline, it is possible to characterize the bunch train longitudinal property. This paper briefly introduced the measurement layout in our lab and reported the recent experiment results, including bunch train profile measurement and longitudinal phase space. The main sources of error are also discussed.

THPC121

Design and Cold Tests of a Prototype photocathode RF Gun for Shanghai SXFEL Facility

3170

H.J. Qian, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, X.H. Liu, X. H. Lu, C.-X. Tang
TUB, Beijing, People's Republic of China

A soft X-ray (~9 nm) FEL (SXFEL) facility is going to be constructed in Shanghai, China, which requires high charge (>500 pC) electron beam with low transverse emittance (<1.5 mm-mrad) at photoinjector exit. One of the keys to achieve a low emittance with high charge is high gradient on the photocathode, so an S-band photocathode RF gun modified from BNL type gun is designed, which aims running 100 MV/m peak gradient at 10 Hz. By changing the cathode seal technique, removing the insertion RF tuner, and reducing the peak surface field, RF breakdown possibility is reduced. Besides, RF pulse width is also considered to be reduced to lower the RF breakdown possibility. Since zero mode and multipole field degrades the beam emittance, they are also suppressed in the new gun design. Design details and cold testing results are presented in this paper.

Paper	Title	Page
TUXA01	Status and Challenges of the China Spallation Neutron Source	889
	S. Fu, H. Chen, Y.W. Chen, Y.L. Chi, H. Dong, L. Dong, S.X. Fang, K.X. Huang, W. Kang, J. Li, L. Ma, H.F. Ouyang, H. Qu, H. Sun, J. Tang, C.H. Wang, Q.B. Wang, S. Wang, T.G. Xu, Z.X. Xu, X. Yin, C. Zhang, J. Zhang IHEP Beijing, Beijing, People's Republic of China
	The accelerator complex of China Spallation Neutron Source (CSNS) mainly consists of an H⁻ linac of 80 MeV and a rapid-cycling synchrotron of 1.6 GeV. It operates at 25 Hz repetition rate with an initial proton beam power of 100 kW and is upgradeable to 500kW. The project will start construction in the middle of 2011 with a construction period of 6.5 years. The CSNS accelerator is the first large-scale, high-power accelerator project to be constructed in China and thus we are facing a lot of challenges. This paper presents the current status of CSNS project and summarizes the technology development during the past several years.
	Slides TUXA01 [3.444 MB]

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.

MOPC022	Development of a Compact C-band Photocathode RF Gun	116
	X.H. Liu, H. Chen, W.-H. Huang, H.J. Qian, C.-X. Tang, Z. Zhang TUB, Beijing, People's Republic of China
	Funding: This work is supported by National Natural Science Foundation of China and National Basic Research Program of China (973 Program). A C-band photocathode RF gun for a compact electron diffraction facility is developed in Tsinghua University, which is designed to work at the frequency of 5.712GHz. This paper presents the physics and structure design of this C-band RF gun, and the comparison on beam dynamics of S-band and C-band photoinjector has been done. Some new structure design will be adopted in this gun, including the optimized cavity length and elliptical iris, which is helpful to achieve lower emittance and larger mode separation.

MOPC023	Design of a C-band 6 MeV Standing-wave Linear Accelerating Structure	119
	J.H. Shao, H. Chen, Q.Z. Xing TUB, Beijing, People's Republic of China
	We design a C-band standing-wave biperiodic on-axis coupled linear accelerating structure for industrial and medical applications. It’s less than 300mm long; consists of 3 bunching cells and 9 normal cells. It can accelerate electrons to 6MeV and the pulsed beam current is 100mA. The RF power source is a 2.5MW magnetron. We implement 2D cells geometry optimization by SUPERFISH, beam dynamics study by PARMELA and full scale 3D calculations by MAFIA codes.

TUPC110	Ultrashort Bunch Train Longitudinal Diagnostics using RF Deflecting Structure	1275
	Y. Yang, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, L.X. Yan TUB, Beijing, People's Republic of China
	Ultrashort electron bunch train has been produced using UV laser stacking in Tsinghua University. With an S-band deflecting cavity inserted into the Tsinghua Thomson Scattering beamline, it is possible to characterize the bunch train longitudinal property. This paper briefly introduced the measurement layout in our lab and reported the recent experiment results, including bunch train profile measurement and longitudinal phase space. The main sources of error are also discussed.

THPC121	Design and Cold Tests of a Prototype photocathode RF Gun for Shanghai SXFEL Facility	3170
	H.J. Qian, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, X.H. Liu, X. H. Lu, C.-X. Tang TUB, Beijing, People's Republic of China
	A soft X-ray (~9 nm) FEL (SXFEL) facility is going to be constructed in Shanghai, China, which requires high charge (>500 pC) electron beam with low transverse emittance (<1.5 mm-mrad) at photoinjector exit. One of the keys to achieve a low emittance with high charge is high gradient on the photocathode, so an S-band photocathode RF gun modified from BNL type gun is designed, which aims running 100 MV/m peak gradient at 10 Hz. By changing the cathode seal technique, removing the insertion RF tuner, and reducing the peak surface field, RF breakdown possibility is reduced. Besides, RF pulse width is also considered to be reduced to lower the RF breakdown possibility. Since zero mode and multipole field degrades the beam emittance, they are also suppressed in the new gun design. Design details and cold testing results are presented in this paper.