Abstract: An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

Abstract: A charged particle beam deflector having a bimodal resonant cavity through which a charged particle beam is passed along the cavity axis. The cavity is excited in a first mode by applying a first rf signal to the cavity through a first magnetic feed loop on the side of the cavity, and in a second mode orthogonal to the first mode by applying a second rf signal to the cavity through a second magnetic feed loop located on the side of the cavity at a circumferential angle of approximately 90.degree. from the first feed loop. The first mode deflects the beam along a first diametric axis passing through the cavity axis and the first loop location and the second mode deflects the beam along a second diametric axis which is substantially perpendicular to the first diametric axis. The rf signals to the feed loops are normally of identical frequency but may differ in ampitude and in phase from one another or from the beam to provide various controlled scan patterns.