Injector and Bunchers of the Electron Linac for High-Intensity Single-Bunch Beam Generation at ISIR

(MO-3-07)

S. Okuda, T. Yamamoto, S. Suemine and G. Isoyama  

ISIR, Osaka University

High-intensity single-bunch electron beams are generated with the 38 MeV L-band (1300 MHz) linear accelerator (linac) at the Institute of Scientific and Industrial Research (ISIR) in Osaka University. The maximum charge of electrons in a bunch of the beam is 81 nC at an energy of 27 MeV and the bunch lengths are 20-30 ps FWHM. The beams are being used for experiments of the self-amplified spontaneous emission and the coherent radiation. In the linac electron beams are injected from a thermionic triode gun which has been developed recently, at a pulse width of 5 ns FWHM. The maximum peak current of the beam from the gun is 30.1 A for an anode voltage of 100 kV. The beam is focused and is injected to three subharmonic prebunchers (SHPBs) with coaxial single-gap cavities (two operated at 108 MHz and one at 216 MHz) and two bunchers at the fundamental frequency. The peak power of the microwave supplies to the SHPB is 10-20 kW. The operational conditions of these components and the performance of the electron beams are presented.