Design of Accelerating Structure on a Novel Compact Electron Linac

Abstract：

This paper mainly discusses what type of accelerating structure should be chosen for a novel compact electron linac (NCEL for short). After simulation of dynamics process in this linac with Parmela program,we get to the point that it is better on the whole,to choose constant impedance accelerating structure than constant gradient accelerating structure on the NCEL of 10MeV class.In this NCEL,the spent beam of a high power klystron amplifier is used for injecting into an accelerator section and the klystron works in self excited mode of operation. In this paper,the simulations of dynamics process,when the spent beam of a high power 5MW klystron is injected into a constant gradient structure and a constant impedance structure,are carried out. By comparing the output beam performances of these two kinds of structures,one can draw the conclusion that from overall consideration,it will be better to equip the NCEL with constant impedance structure than constant gradient structure,especially when the spent beam of much higher power klystron is used. At the same time the result of simulation indicates that it is unnecessary to use focusing coils around accelerating section,and thus the design will be further simplified for the NCEL.