用于短波长FEL的光阴极微波电子枪设计研究

Design Studies of a Photocathode RF Gun for Short-Wavelength FELs

高增益、短波长自由电子激光器需要发射度低、峰值电流高的短脉冲电子束流 .采用发射度补偿技术 ,设计了一台S波段、一个半腔体的光阴极微波电子枪以用于建议中的SDUV FEL装置 .POISSON ,SUPERFISH和PARMELA程序的计算表明 :当微脉冲电量为 2nC时 ,这种设计能产生εn ,rms=2 3π·mm·mrad、Ek=4 8MeV的电子束流 .

Low emittance and high intensity electron beams are needed for the high gain, short wavelength FELs. To meet the requirements of the proposed DUV FEL facility in Shanghai, we designed a 1.5-cell, S-band photocathode RF gun using the emittance compensation techniques. Based on the simulation codes of POISSON, SUPERFISH and PARMELA, this design aims at producing a beam of ε n,rms =2.3π·mm·mrad, Q=2 nC/bunch, E k=4.8 MeV at the gun exit with the field gradient of 100MV/m on the cathode. In this paper, we present the design considerations and the simulation results.