Integrated numerical modeling of a laser gun injector

CEBAF is planning to incorporate a laser gun injector into the linac front end as a high-charge cw source for a high-power free electron laser and for nuclear physics. This injector consists of a DC laser gun, a buncher, a cryounit and a chicane. The performance of the injector is predicted based on integrated numerical modeling using POISSON, SUPERFISH and PARMELA. The point-by-point method incorporated into PARMELA by McDonald (1988) is chosen for space charge treatment. The concept of “conditioning for final bunching” is employed to vary several crucial parameters of the system for achieving highest peak current while maintaining low emittance and low energy spread. Extensive parameter variation studies show that the design will perform better than the specifications for FEL operations aimed at industrial applications and fundamental scientific research. The calculation also shows that the injector will perform as an extremely bright cw electron source