Multiple Beam Pulse Capability of the Slac Injector

The SLAC injector is capable of being programmed for multiple beams of different beam pulse width and intensity on a pulse to pulse basis. Programming is accomplished remotely from the central control building, two miles away. The beam starts at the SLAC gun which is a Pierce triode with cathode operated at -80 KVDC. The gun modulator drives the grid-cathode gap with an 800 volt pulse of selectable pulse width. Selectable grid-cathode bias controls the current output of the gun. These selections are made on a pulse to pulse basis as required for multiple beam operation. For time of flight experiments which require a series of very short pulses, or even a series of single bunches of electrons, a transverse sweeper phase locked to a subharmonic of the bunching frequency is used in the injector to chop the beam accordingly.