Low energy electron linacs and their applications in China

In recent years, low energy electron linacs have been developed for radiotherapy and radiography applications as well as irradiation processing. There are now about 200 domestic made low energy linacs in China. Among them, about 155 sets are standing-wave (SW) medical linacs with electron beam energies from 4 to 6 MeV. A 14 MeV SW electron linac with a 270deg deflecting system for radiotherapy has been produced. Eight sets of SW electron linacs including two 9 MeV linacs for radiography have been constructed. The major accelerator for irradiation processing use is the Dynamitron, but also several domestic made electron linacs with beam energy more than 4 MeV are under operation for this application. Tsinghua University has developed a backward travelling wave (BTW) accelerator structure and a portable X-band SW electron accelerator structure for low energy application. (author)