Getting short bunches from a 2-MeV electron injector

A 2-MeV electron injector for the Novosibirsk high-power FEL driven by a 100-MeV racetrack microtron-recuperator was built and commissioned in 1998. It is intended to supply electron bunches of ∼100 ps duration and repetition rate up to 22.5 MHz with average and peak current 45 mA and ∼20 A respectively. The RF-system of the injector is designed to provide stable operation under heavy beam loading. Various problems of bunching and beam transport in the injector are discussed. A number of experimental results are presented.