FEL2011 - List of Authors (Li, M.)

Paper	Title	Page
MOPB15	Numerical Simulation of CAEP Compact FEL THz Source	35
	L.J. Chen, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China M. Li, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	Free Election Laser Terahertz source is a good choice for THz source, whose wavelength is tunable. Using 1D FEL stimulation code FELO, we simulate the output characteristic of China Academy of Engineering Physics (CAEP) FEL THz, which is a waveguide FEL oscillator. The beam qualitys’ influence on the operation of FEL, such as energy dispersion, emittance and beam current, have been studied to designate a set of beam parameters. Besides, the output performance of FEL at different output coupling ratio is analyzed. The cavity detuning is discussed too. Meanwhile the influence of the position of the undulator in the cavity on the FEL performance is also studied.

TUPA08	The Control System for CAEP FEL	206
	D. Zhang, M. Li, H.B. Wang, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	It describes a control system of CAEP Free Electron Laser (FEL), which is a distributed control system based on EPICS and Visual C++6.0. EPICS is popular in large accelerator laboratories in the world. It is a software toolkit for building process control system for a wide variety of experiment and industrial applications. The software tools in the kit provide independent and expandable modules for system configuration, distributed process control, run-time database, alarm manager, etc. It gives detailed description of the magnet power supply system , beam diagnostic system, including the hardware structure and software design. Other subsystems are also described in the paper. The control system has standard module, interoperability, and repeatability are available. The control system is simple direct, and stable.

WEPA12	The Driving Laser for FEL-THz	349
	Y. Chen, M. Li, H.B. Wang, D. Wu, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	A solid-state driving laser system have been developed to meet the requirements of the FEL-THz research. The design specifications, configuration and diode-pumped amplifier of the drive-laser system are also described. The laser system can generate continuous or 10μs-20μs pulses light with wavelength 10⁶⁴ nm, 532nm, 266nm at a repetition rate 54.167MHz. The average power of the driving laser system is more than 25W, 8W, 1W at wavelength 1064nm, 532nm, 266nm respectively. The cathode material is GaAs. The second harmonic is used, of which average power is 8.55W, pulse width is about 12ps, power stability is 0.72% and pointing stability is 46urad.

WEPA21	Research of Emittance Compensation of CAEP CW DC-Gun Photoinjector	377
	P. Li, M. Li, D. Wu, Z. Xu, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	Emittance growth is very import for photo-cathode injector due to space charge effect. The emittance compensation technology will be used on the 350 kV photo-cathode DC gun for the CAEP CW FEL, where the energy of electron beam is extremely low and Emittance growth is great severity. In this paper, the space charge force and its effect on electron beam transverse emittance is discussed, the principle of emittance compensation in phase space is analyzed. And a solenoid for emittance compensation is designed. Its beam dynamics has been studied by the PARMELA code. Simulation results indicate that the normalized transverse RMS emittance for electron beam of 80 pC is 1.267 mm•mrad with σ_r=1.5 mm, σ_z=4.25 pS.

WEPA23	DEVELOPMENT OF AN ITC-RF GUN FOR COMPACT THz FEL	385
	W. Bai, Y. Chen, M. Li, L.J. Shan, X.M. Shen, H.B. Wang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	An independent tunable cells thermionic rf gun (ITC-RF Gun) used for compact Tera-hertz (THz) free electron laser(FEL) is developed at Institute of Applied Electronics, China Academy of Engineering Physics (CAEP). This RF-gun consists of a single cell and a 3-cells accelerating cavity which are excited independently, so the amplitude and phase of the two parts can be adjusted easily. The paper introduces some results of the simulation, cold test and preliminary hot test. The test results agree well with the theoretical design.

THPA13	A 54.167MHz Laser Wire System for Free Electron Laser in CAEP	493
	D. Wu TUB, Beijing, People's Republic of China W. Bai, M. Li, H.B. Wang, J. Wang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	The laser wire (LW) method has been demonstrated as an effective non-interceptive technique for measuring transverse electron beam size of CW FELs and ERLs. To measure the beam size of a CW DC gun, which is built as an electron source of THz FEL in China Academy of Engineering Physics (CAEP), a high repetition LW system is proposed. The first proposed system is going to be installed at the exit of the DC gun, where the energy of electron beam is extremely low. In this paper, the LW system adapted to the FEL beam parameters is discussed, and the main parameters are given.

THPA33	Bunch Length Measurement Based on the Beam Position Monitor	555
	J. Wang, M. Li, H.B. Wang, D. Wu CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	BPM (Beam Position Monitor) is the most basic instrument of the beam dynamics. The signal of the BPM consist more information of the beam apart from the beam position. By processing and analyzing of the BPM signal, the information of the bunch length can be got. It's a challenge to use this method when the energy is low (<30 MeV) and the bunch length is especially short(10 ps rms). In this paper, the BPM system which can be used to measure the bunch length is discussed. And the method of the signal processing and analyzing is given.

THPB20	DC High Voltage Photoemission Electron Gun for CAEP FEL	598
	H.B. Wang, M. Li, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	The research on high average power Terahertz free electron laser requires more demanding specifications of electron source. DC high voltage electron guns with photoemission cathodes are a natural choice for generating the critical beams considering the condition of technology. Field emission from the electrode structures limits the operating voltage and cathode field gradient in these guns. A ceramic insulator determines the level of operating voltage. The photocathode operational lifetime is limited by the gun vacuum and by ion back bombardment. The designing thought and the technical solution to aforementioned issues are presented. The results of the beam dynamic simulation based on the design are displayed, normalized emittance at the location 120 cm far from the cathode surface: x=1.335 πmmmrad, y=1.364 πmmmrad, z=4.81 π*keV-deg, using the following initial beam parameters: the laser spot 4 mm in diameter, the laser pulse length FWHM 12 ps, the charge per bunch 35 pC and the accelerating voltage 350 kV. Now the DC photoemission gun is conditioning.

Paper

Title

Page

Numerical Simulation of CAEP Compact FEL THz Source

35

L.J. Chen, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China
M. Li, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

Free Election Laser Terahertz source is a good choice for THz source, whose wavelength is tunable. Using 1D FEL stimulation code FELO, we simulate the output characteristic of China Academy of Engineering Physics (CAEP) FEL THz, which is a waveguide FEL oscillator. The beam qualitys’ influence on the operation of FEL, such as energy dispersion, emittance and beam current, have been studied to designate a set of beam parameters. Besides, the output performance of FEL at different output coupling ratio is analyzed. The cavity detuning is discussed too. Meanwhile the influence of the position of the undulator in the cavity on the FEL performance is also studied.

TUPA08

The Control System for CAEP FEL

206

D. Zhang, M. Li, H.B. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

It describes a control system of CAEP Free Electron Laser (FEL), which is a distributed control system based on EPICS and Visual C++6.0. EPICS is popular in large accelerator laboratories in the world. It is a software toolkit for building process control system for a wide variety of experiment and industrial applications. The software tools in the kit provide independent and expandable modules for system configuration, distributed process control, run-time database, alarm manager, etc. It gives detailed description of the magnet power supply system , beam diagnostic system, including the hardware structure and software design. Other subsystems are also described in the paper. The control system has standard module, interoperability, and repeatability are available. The control system is simple direct, and stable.

WEPA12

The Driving Laser for FEL-THz

349

Y. Chen, M. Li, H.B. Wang, D. Wu, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

A solid-state driving laser system have been developed to meet the requirements of the FEL-THz research. The design specifications, configuration and diode-pumped amplifier of the drive-laser system are also described. The laser system can generate continuous or 10μs-20μs pulses light with wavelength 10⁶⁴ nm, 532nm, 266nm at a repetition rate 54.167MHz. The average power of the driving laser system is more than 25W, 8W, 1W at wavelength 1064nm, 532nm, 266nm respectively. The cathode material is GaAs. The second harmonic is used, of which average power is 8.55W, pulse width is about 12ps, power stability is 0.72% and pointing stability is 46urad.

WEPA21

Research of Emittance Compensation of CAEP CW DC-Gun Photoinjector

377

P. Li, M. Li, D. Wu, Z. Xu, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

Emittance growth is very import for photo-cathode injector due to space charge effect. The emittance compensation technology will be used on the 350 kV photo-cathode DC gun for the CAEP CW FEL, where the energy of electron beam is extremely low and Emittance growth is great severity. In this paper, the space charge force and its effect on electron beam transverse emittance is discussed, the principle of emittance compensation in phase space is analyzed. And a solenoid for emittance compensation is designed. Its beam dynamics has been studied by the PARMELA code. Simulation results indicate that the normalized transverse RMS emittance for electron beam of 80 pC is 1.267 mm•mrad with σ_r=1.5 mm, σ_z=4.25 pS.

WEPA23

DEVELOPMENT OF AN ITC-RF GUN FOR COMPACT THz FEL

385

W. Bai, Y. Chen, M. Li, L.J. Shan, X.M. Shen, H.B. Wang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

An independent tunable cells thermionic rf gun (ITC-RF Gun) used for compact Tera-hertz (THz) free electron laser(FEL) is developed at Institute of Applied Electronics, China Academy of Engineering Physics (CAEP). This RF-gun consists of a single cell and a 3-cells accelerating cavity which are excited independently, so the amplitude and phase of the two parts can be adjusted easily. The paper introduces some results of the simulation, cold test and preliminary hot test. The test results agree well with the theoretical design.

THPA13

A 54.167MHz Laser Wire System for Free Electron Laser in CAEP

493

D. Wu
TUB, Beijing, People's Republic of China
W. Bai, M. Li, H.B. Wang, J. Wang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

The laser wire (LW) method has been demonstrated as an effective non-interceptive technique for measuring transverse electron beam size of CW FELs and ERLs. To measure the beam size of a CW DC gun, which is built as an electron source of THz FEL in China Academy of Engineering Physics (CAEP), a high repetition LW system is proposed. The first proposed system is going to be installed at the exit of the DC gun, where the energy of electron beam is extremely low. In this paper, the LW system adapted to the FEL beam parameters is discussed, and the main parameters are given.

THPA33

Bunch Length Measurement Based on the Beam Position Monitor

555

J. Wang, M. Li, H.B. Wang, D. Wu
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

BPM (Beam Position Monitor) is the most basic instrument of the beam dynamics. The signal of the BPM consist more information of the beam apart from the beam position. By processing and analyzing of the BPM signal, the information of the bunch length can be got. It's a challenge to use this method when the energy is low (<30 MeV) and the bunch length is especially short(10 ps rms). In this paper, the BPM system which can be used to measure the bunch length is discussed. And the method of the signal processing and analyzing is given.

THPB20

DC High Voltage Photoemission Electron Gun for CAEP FEL

598

H.B. Wang, M. Li, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

The research on high average power Terahertz free electron laser requires more demanding specifications of electron source. DC high voltage electron guns with photoemission cathodes are a natural choice for generating the critical beams considering the condition of technology. Field emission from the electrode structures limits the operating voltage and cathode field gradient in these guns. A ceramic insulator determines the level of operating voltage. The photocathode operational lifetime is limited by the gun vacuum and by ion back bombardment. The designing thought and the technical solution to aforementioned issues are presented. The results of the beam dynamic simulation based on the design are displayed, normalized emittance at the location 120 cm far from the cathode surface: x=1.335 π*mm*mrad, y=1.364 π*mm*mrad, z=4.81 π*keV-deg, using the following initial beam parameters: the laser spot 4 mm in diameter, the laser pulse length FWHM 12 ps, the charge per bunch 35 pC and the accelerating voltage 350 kV. Now the DC photoemission gun is conditioning.