Design Study on an Electron Linac for Irradiation Processing with a High Capture Efficiency

Abstract：

The accelerating tube is the core of a linac. The capture efficiency is usually about 50% by ordinary design method in the electron linac for irradiation processing. Nearly half of the injected electrons are lost in the tube, resulting in strong radiation and additional heat load on the accelerating cavity, as well as a bad effect on vacuum. In this paper, a constant gradient accelerating structure is chosen to accelerate the electron beam, and the designed phase velocity is linearly increased along the tube. By adjusting the size of the accelerating cavity and the phase velocity function, a high capture efficiency is reached. After a series of simulations, we obtain a 90% capture efficiency, while the accelerator length is not increased due to the bunching process.