Short-bunch generation from an rf photoinjector with injection phase compensation

Abstract

A radio-frequency photoinjector is widely used for generating picosecond-femtosecond electron bunches. During particle acceleration, the electron bunch shape varies under the influence of both the acceleration fields and space charge fields. To restore a distorted electron bunch, we propose an injection phase compensation technique for the electrons by illuminating the photocathode with a pulse-front-corrected laser pulse. Using an S-band 1.6-cell photoinjector as an example, our study shows that the proposed technique can generate nearly undistorted electron bunches up to a bunch rate of a few hundred terahertz.