Injector of the positron generator

Main components of the Positron Generator injector are briefly described, which include an electron gun, a subharmonic buncher (SHB), a prebuncher and a buncher, an rf waveguide, a transport and a vacuum system, etc. The vacuum system around the gun was carefully made to obtain a high emission current. The SHB was introduced to increase the peak current and operates at 119 MHz, the 24th subharmonic frequency. Performance of the injector has been tested yielding the results that about 60% of the injected current from the gun is successfully accelerated without the SHB. An injection current obtained is typically 7 A for 5 nsec pulse. For 3 nsec (FWHM) beam the accelerated electron and the positron beams are increased by a factor of 1.5 with the SHB