Conceptual design of a high current injector for the NIST-NRL free electron laser

The NIST-LANL (National Institute of Standards and Technology-Los Alamos National Laboratory) racetrack microtron (RTM) is to be used as a driver for a CW free-electron laser. To achieve the peak currents of 2.4 A required for lasing, 15-ps, 120-keV electron pulses at 66.111 MHz with 7-14 pC/pulse will be accelerated to 5 MeV by the existing injector linac for injection into the RTM. The conceptual design of a high-current injection system to produce this beam using a pulsed electron gun and subharmonic chopping and bunching is described, and the results of PARMELA calculations are presented. The new injector uses conventional, proven technology similar to that used in the present injector, which has operated successfully.<>