Design and initial operation of the ETA-II induction accelerator

ETA-II is a high current, high-repetition-rate induction linac designed for use in free-electron laser (FEL) research. ETA-II design is to produce 7.5-MeV, 2-kA, 70-ns pulses at a brightness of 2 x 109 A/(m-rad)2 with a repetition rate of up to 100 Hz continuous or 5 kHz in a burst mode. The pulse power is generated by pulse compression using magnetic switching. The accelerator consists of a 1.5-MeV injector using an M-type dispenser cathode followed by bO induction cells. Each cell adds 100 keV to the beam. ETA-II will be used for brightness transport studies needed for the design of higher energy accelerators for visible-light FELs. ETA-II will also drive a microwave FEL at 140 GHz and 250 GHz for plasma heating experiments in a tokamak. This report will describe the design parameters and initial operation of ETA-II. 1 ref., 8 figs., 2 tabs