IPAC2013 - List of Authors (Pei, Y.J.)

Paper	Title	Page
TUPWO034	Focusing Magnetic Field Design for a FEL Linac	1949
	Q.S. Chen, Q. Fu, T. Hu, B. Qin, B. Wu, H. Zeng HUST, Wuhan, People's Republic of China J. Li, Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	A linac-based Free Electron Laser is planned to be built in Huazhong University of Science and Technology (HUST). As an important part of the whole project, the focusing magnetic field is carefully designed. Space-charge force is calculated at first to give a rough evaluation about the focusing field. Start-to-end simulation shows that the magnetic field has only great effect on spot size and phase space. With the final designed field, 10-ps-length pulse containing 200pC electrons can be got and the corresponding RMS emittance and RMS radius are 7 πmm•mrad and 0.25 mm, respectively. Finally, a new idea (double-peak scheme) is discussed and excitation current is proposed as the evaluation index.

TUPWO035	Physical Design of Beam Transport Line of a Compact Terahertz FEL	1952
	H. Zeng, Q.S. Chen, Q. Fu, B. Qin, B. Wu, Y.Q. Xiong HUST, Wuhan, People's Republic of China G. Feng, Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	The single pass, linac-based compact terahertz source at HUST is now in the physical design stage. To match Twiss parameters and dispersion function of the electron beam at the undulator entrance and get smaller beta function in the whole line, several lattices based on the double bending achromat(DBA) structure were discussed and the optimized design is given with beam dynamics results–calculated by MAD and Trace 3D.

WEPWA023	Design of 14 MeV LINAC for THz Source Based FEL	2181
	Y.J. Pei, G. Feng, Y. Hong, G. Huang, D. Jia, K. Jin, C. Li, J. Li, S. Lu, L. Shang USTC/NSRL, Hefei, Anhui, People's Republic of China Q.S. Chen, M. Fan, T. Hu, Y.Q. Xiong, H. Zeng HUST, Wuhan, People's Republic of China B. Qing, Z.X. Tang, X.L. Wei USTC, Hefei, Anhui, People's Republic of China L.G. Shen, F. Zhang USTC/PMPI, Hefei, Anhui, People's Republic of China
	Abstract THz wave have many special performances, such as it can penetrate deep into many organic materials without the damage associated with ionizing radiation such as X-ray, it can be used to distinguish between materials with varying water content, because THz radiation is absorbed by water. In part researchers lacked reliable sources of THz, so develop new THz sources is important now. So far there were many kind of THz Source, one of them is THz source based a FEL that can produce high power (~kW). This paper will describe the design of a LINAC of 14MeV which is used for FEL to produce THz radiation. The LINAC is mainly composed of a novel EC-ITC RF gun, compensation coil, constant gradient accelerating structure, beam diagnostic system and so on. Main design parameters are as following: Energy 7~15MeV Beam current (macro pulse) 571mA (micro pulse) 30~40° Bunch length 5~7ps Charge per bunch 200~300pC Normalized emittance ≤10mm.mrad Energy spread(rms) ≤0.5%

WEPWA024	Study of an Electron Gun for Terahertz Radiation Source	2184
	J. Li, C. Li, Y.J. Pei, L. Shang USTC/NSRL, Hefei, Anhui, People's Republic of China Q.S. Chen, T. Hu HUST, Wuhan, People's Republic of China G. Feng DESY, Hamburg, Germany
	With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an RF gun with independently tunable cells (ITC) was employed. As the electron source of the ITC RF gun, a grid-control DC gun plays a key role, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the grid-control DC gun should be 15 KeV at most. A proper structure of the grid-gun is shown to overcome the strong space charge force on the cathode, which is able to generate 1us beam with 4.5A current successfully. Simulations considering the grid net are also introduced.

THPFI035	Design of A 4-cavities Collinear Load Coated with FeSiAl Alloy for 14 MeV LINAC	3370
	F. Zhang, L.G. Shen USTC/PMPI, Hefei, Anhui, People's Republic of China Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	Collinear load is a substitute for waveguide load to miniaturize linear accelerator and make the beam quality better. Coating with a kind of high efficient microwave-absorbing material FeSiAl alloy, a collinear load section composed of 4 cavities (at 2 /3 mode) with different coating dimensions is designed to absorb 4kW remnant power. Cavity dimensions are adjusted to compensate the frequency shift from 2856 MHz respectively. Simulation shows the loss material FeSiAl only need to be coated on the inner surface of the ring. This makes the design and construction of the cooling system for the load segment easier. Coming with a specific water cooling system can makes the working frequency of the accelerator and the collinear load more close to the supposed. Eventually, based on optimized uniform power absorption principle concluded from the simulation of temperature field, a four-cavity collinear load is designed with one-way attenuation of 76.1 dB, while the largest shift from operation frequency is 35 kHz.

Paper

Title

Page

Focusing Magnetic Field Design for a FEL Linac

1949

Q.S. Chen, Q. Fu, T. Hu, B. Qin, B. Wu, H. Zeng
HUST, Wuhan, People's Republic of China
J. Li, Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

A linac-based Free Electron Laser is planned to be built in Huazhong University of Science and Technology (HUST). As an important part of the whole project, the focusing magnetic field is carefully designed. Space-charge force is calculated at first to give a rough evaluation about the focusing field. Start-to-end simulation shows that the magnetic field has only great effect on spot size and phase space. With the final designed field, 10-ps-length pulse containing 200pC electrons can be got and the corresponding RMS emittance and RMS radius are 7 πmm•mrad and 0.25 mm, respectively. Finally, a new idea (double-peak scheme) is discussed and excitation current is proposed as the evaluation index.

TUPWO035

Physical Design of Beam Transport Line of a Compact Terahertz FEL

1952

H. Zeng, Q.S. Chen, Q. Fu, B. Qin, B. Wu, Y.Q. Xiong
HUST, Wuhan, People's Republic of China
G. Feng, Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

The single pass, linac-based compact terahertz source at HUST is now in the physical design stage. To match Twiss parameters and dispersion function of the electron beam at the undulator entrance and get smaller beta function in the whole line, several lattices based on the double bending achromat(DBA) structure were discussed and the optimized design is given with beam dynamics results–calculated by MAD and Trace 3D.

WEPWA023

Design of 14 MeV LINAC for THz Source Based FEL

2181

Y.J. Pei, G. Feng, Y. Hong, G. Huang, D. Jia, K. Jin, C. Li, J. Li, S. Lu, L. Shang
USTC/NSRL, Hefei, Anhui, People's Republic of China
Q.S. Chen, M. Fan, T. Hu, Y.Q. Xiong, H. Zeng
HUST, Wuhan, People's Republic of China
B. Qing, Z.X. Tang, X.L. Wei
USTC, Hefei, Anhui, People's Republic of China
L.G. Shen, F. Zhang
USTC/PMPI, Hefei, Anhui, People's Republic of China

Abstract THz wave have many special performances, such as it can penetrate deep into many organic materials without the damage associated with ionizing radiation such as X-ray, it can be used to distinguish between materials with varying water content, because THz radiation is absorbed by water. In part researchers lacked reliable sources of THz, so develop new THz sources is important now. So far there were many kind of THz Source, one of them is THz source based a FEL that can produce high power (~kW). This paper will describe the design of a LINAC of 14MeV which is used for FEL to produce THz radiation. The LINAC is mainly composed of a novel EC-ITC RF gun, compensation coil, constant gradient accelerating structure, beam diagnostic system and so on. Main design parameters are as following: Energy 7~15MeV Beam current (macro pulse) 571mA (micro pulse) 30~40° Bunch length 5~7ps Charge per bunch 200~300pC Normalized emittance ≤10mm.mrad Energy spread(rms) ≤0.5%

WEPWA024

Study of an Electron Gun for Terahertz Radiation Source

2184

J. Li, C. Li, Y.J. Pei, L. Shang
USTC/NSRL, Hefei, Anhui, People's Republic of China
Q.S. Chen, T. Hu
HUST, Wuhan, People's Republic of China
G. Feng
DESY, Hamburg, Germany

With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an RF gun with independently tunable cells (ITC) was employed. As the electron source of the ITC RF gun, a grid-control DC gun plays a key role, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the grid-control DC gun should be 15 KeV at most. A proper structure of the grid-gun is shown to overcome the strong space charge force on the cathode, which is able to generate 1us beam with 4.5A current successfully. Simulations considering the grid net are also introduced.

THPFI035

Design of A 4-cavities Collinear Load Coated with FeSiAl Alloy for 14 MeV LINAC

3370

F. Zhang, L.G. Shen
USTC/PMPI, Hefei, Anhui, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

Collinear load is a substitute for waveguide load to miniaturize linear accelerator and make the beam quality better. Coating with a kind of high efficient microwave-absorbing material FeSiAl alloy, a collinear load section composed of 4 cavities (at 2 /3 mode) with different coating dimensions is designed to absorb 4kW remnant power. Cavity dimensions are adjusted to compensate the frequency shift from 2856 MHz respectively. Simulation shows the loss material FeSiAl only need to be coated on the inner surface of the ring. This makes the design and construction of the cooling system for the load segment easier. Coming with a specific water cooling system can makes the working frequency of the accelerator and the collinear load more close to the supposed. Eventually, based on optimized uniform power absorption principle concluded from the simulation of temperature field, a four-cavity collinear load is designed with one-way attenuation of 76.1 dB, while the largest shift from operation frequency is 35 kHz.