Compact RF accelerator for electron beam irradiation

A compact re-entrant coaxial type electron accelerator (inner size: height 650 mm, diameter 550 mm) has been developed for electron beam processing. The resonant frequency of the resonator is 175 MHz and the Q-value 15000. The resonator is capacitively coupled to a feeder line and powered by a new type self-excited oscillator using a tetrode. The cathode of the electron gun consists of a single crystal of lanthanum hexa-boride (LaB6) that can emit the beam current of more than 400 mA. The maximum beam energy is 900 keV and the energy resolution (FWHM) is better than 5% by the use of a new type buncher integrated into the accelerating electrode.