Design of a photocathode DC-gun for generating train of sheet-shaped electron bunches

Using the superradiant Smith-Purcell radiation from a train of periodic electron-bunches interacting with a grating is an efficient way for generating terahertz radiation beyond the frequency region of traditional vacuum electron devices. The producing of a train of well-shaped electron bunches is essential for these radiation schemes. Here we design and simulate a photocathode DC-gun driven by train of laser pulses, aiming to generating train of sheet-shaped electron bunches for practices. The effects of main structural parameters and of laser properties on the performances of electron gun are investigated. It will set an important base for the development and improvement of practical electron guns in experiments.