C波段2 MeV驻波加速管物理设计

 为了发展结构紧凑、小束斑加速器，进行了C波段驻波电子直线加速器加速管的物理设计和研究。利用多级聚束和大孔径注入方法，抑制空间电荷效应。加速管由3个聚束腔和4个加速腔组成，长约163 mm，馈入微波功率源1 MW。在最终的数值模拟中，得到脉冲电流约150 mA，俘获效率优于30％，在加速管出口外约14 mm处，对电子的横向分布进行非线性Gauss拟合，得到束斑直径（FWHM）约为0.55 mm。

Physical design of 2 MeV standing wave accelerating tube

In order to develop compact accelerators with small beam spot, a C-band 5.52 GHz 2 MeV SW accelerating tube is physically designed and studied, which operated in the π/2 mode. Not using any exterior focusing element,transverse emittance growth aroused from space charge effect is restrained efficiently by repeatedly bunching and utilizing dissymmetry field of first cavity. The accelerating tube consists of 3-cell buncher and 4-cell accelerating section with a total length of about 163 mm,excited with 1 MW magnetron. In final dynamics simulation, 2 MeV 150 mA beam pulse current is obtained, and the capture efficiency is more than 30%. By means of nolinear Gauss fit on electron transverse distribution, the diameter of beam spot (Full Width at Half Maximum of density distribution) is about 0.55 mm.