Interactions of relativistic electron beams with X-band microwaves

Summary form only given. Time-dependent extinction of microwave transmission through relativistic electron beams has been measured for probe frequencies. 7.2, 9.2, and 11.2 GHz in the fundamental TE/sub 10/ mode using the WR112 rectangular waveguide. The goal is the development of high bandwidth electron density diagnostics in the relativistic regime. Electrons are delivered by a 2 MeV accelerator. Current densities near 10 KA/cm/sup 2/ are incident on a thin-walled portion of the waveguide. Electron propagation is aimed transvere to that of the microwave probe, including cases parallel and perpendicular to the microwave electric field. Electron density was determined using a calibrated Rogowski probe and an optical streak camera. By sampling with a unidirectional waveguide coupler, microwave transmission was measured using conventional filtered diode envelope detection as well as a high bandwidth heterodyne technique incorporating 6-GHz bandwidth oscilloscopes.