Effect of self-injected electrons driven by paralleled drive electron bunches

In the case of wake field acceleration driven by charged particle bunches, many researchers focused on adjusting parameters such as magnitude, shape and electrical properties to amplify the maximum energy which drives electrons. Comprehensively considering the existing studies, in the paper we propose a new method of acceleration in which paralleled bunches are used to excite plasma wake field and trap self-injected electrons. It is proved to be more efficient than using single drive beam. With 2.5D PIC code, the driven electrons accelerated by paralleled bunches are found to possess the advantages of acceleration in longer distance, higher energy and better quasimonoenergy. Moreover, a bunch of backflow electrons is observed in the bubble, which makes self-injected electrons well collimated.