Optical beam profile diagnostic for low energy, long pulse, moderate current electron beams

Abstract

Currently ongoing at Los Alamos National Laboratory is a program to develop high-power, planar 100–300GHz traveling-wave tubes. An enabling technology for this effort is a sheet electron beam source and much of our effort has been geared toward understanding sheet beam generation and transport. Toward this end we have developed a robust, high resolution optical diagnostic for measuring the transverse density profiles of our electron beams. The diagnostic consists of a thin metal foil followed by an YAG:Ce or YAP:Ce scintillator crystal, both mounted on a vacuum actuator that allows us to position the foil/scintillator combination at arbitrary positions along the beam’s longitudinal axis. The electron beam strikes the metal foil and is stopped, generating Bremsstrahlung x rays that are imaged by the scintillator crystal. This image is then captured by an optical system using a high-speed, intensified gated camera. Using this diagnostic, we have measured beam profiles with resolutions as low as 0.05mm from ...