LINAC2012 - List of Authors (Zhang, M.)

Paper	Title	Page
SUPB006	Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility	10
	D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

MOPB007	Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility	189
	D. Huang, Q. Gu, M. Zhang SINAP, Shanghai, People's Republic of China
	The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.

TUPB018	Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility	513
	D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

TUPB022	A Passive Linearizer for Bunch Compression	525
	Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown.

Paper

Title

Page

Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility

10

D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

MOPB007

Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility

189

D. Huang, Q. Gu, M. Zhang
SINAP, Shanghai, People's Republic of China

The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.

TUPB018

Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility

513

D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

TUPB022

A Passive Linearizer for Bunch Compression

525

Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown.