Status of the ETA-II (Experimental Test Accelerator II) linear induction accelerator: High brightness results

A two-aperture collimator has been used to measure brightness of the electron beam produced by the injector and the first 20 acceleration cells of the ETA-II linear induction accelerator. Osmium alloy dispenser cathodes produce the electron beam. For accelerated currents up to 1.5 kA with 2.0- to 2.7-MeV beam energies the measured brightness is 5 {times} 10{sup 9} A/(rad-m){sup 2}, exceeding our design goal by a factor of 2. At the highest current, 2.0 kA, a beam brightness of 2.6 {times} 10{sup 9} A/(rad-m){sup 2} has been measured. 6 refs., 5 figs., 2 tabs.