DEVELOPMENT OF A PHOTOCATHODE RF GUN FOR AN L-BAND ELECTRON LINAC

We conduct research on Free Electron Laser (FEL) in the infrared region and pulse radiolysis for radiation chemistry using the 40 MeV, 1.3 GHz L-band linac of Osaka University. At present, the linac is equipped with a thermionic electron gun. It can accelerate a high-intensity single-bunch beam with charge up to 91 nC but the normalized emittance is large. In order to advance the research, we have begun development of a photocathode RF gun for the L-band linac in collaboration with KEK and Hiroshima University. A new design of the L-band RF gun cavity that improves the cooling system for a long RF pulse operation is being developed and the ultraprecision machining is given to the fabrication of the RF gun cavity. The simulation is also performed for the case of a high charge electron beam. Before we install the new L-band RF gun into the L-band linac of Osaka University, we plan to commission the DESY type of L-band RF gun at the Superconducting RF Test Facility of KEK (KEKSTF). The DESY type of gun is fabricated at the Fermi National Accelerator Laboratory (FNAL), and the resonant frequency and field balance of the RF gun cavity have been adjusted using a tuning apparatus at KEK-STF. In this conference, we describe details of the L-band RF gun development.