远红外自由电子激光光腔改进的模拟分析

提出在中物院远红外自由电子激光光腔中全程采用波导对光场进行约束，利用计算光束与电子束横向叠合因子分析了光腔中是否加入波导管对腔内净增益的影响。模拟了减小波导管间隙和提高扭摆器峰值磁场场强对腔内增益的影响。3维数值模拟计算表明在光腔中加入波导使扭摆器净增益由-6%提高到约25%；波导管的间隙每缩小2 mm，腔内净增益提高7％~15％；场强每提高0.02 T，腔内净增益可增加5%~10%。

Analysis and simulation of optical cavity in CAEP far-infrared FEL

The waveguide is used in the whole optical cavity of CAEP far-infrared FEL. The influence of waveguide on the net gain of the optical cavity is estimated by calculating the transverse coupling factor between the optical beam and electron beam. The influence of the waveguide is simulated using 3D code. The simulation experiments have been done by reducing the wave guide gap and enhancing field intensity to increase the optical gain. The results show that the gain can be increased by 7%~15% when the wave-guide gap is reduced by 2 mm, and the net gain can be increased almost by 5%~10% when the magnetic field intensity is enhanced by 0.02 T.