High average current 2-MeV electron accelerator for a high-power free-electron laser

A high average current CW RF electron accelerator has been developed for the free electron laser programs at KAERI. The accelerator is composed of a 300-keV electron gun, one RF bunching cavity, and two RF acceleration cavities. The kinetic energy of the electron beam is 1.5 MeV nominally and 2 MeV at maximum. The duration of a pulse is 350 ps and its repetition rate is variable from a single pulse to 22.5 MHz. The peak current is 6 A, and the average current, at the maximum repetition rate, is 45 mA. The resonant frequency of the RF cavities is 180 MHz. The energy gain of an RF acceleration cavity is 0.6 MeV nominally and 0.85 MeV at maximum. The total RF power supplied into the RF cavities is 262 kW. A millimeter-wave FEL driven by the 2-MeV accelerator is under design. The 2-MeV accelerator will be used as an injector of a high-average-power infrared FEL.