Optical Beam Size Measurements Of The RADLAC II Beam Propagating In Air

Beam parameters of the propagating RAD LAC II beam were measured using both Cherenkov radiation and beam-induced air fluorescence. In this paper we describe the measurement techniques and show representative data, but reserve detailed results relating to electron beam propagation to an accompanying paper. A Thomson streak camera was deployed at z = 1.5 m and a Hamamatsu streak camera was deployed at z = 3.5 m. Micro-channel-plate (MCP) gated cameras were mounted to both streak cameras. Video images from these cameras were digitized and stored, and analyzed after each shot to give beam radius, radius tailoring, and centroid motion. Three MCP gated cameras were also used to give an axial view of the propagating beam. These cameras gave beam radius and centroid versus z for three times in the beam pulse. The video images from these cameras were also digitized, stored and post-analyzed. In addition, several open-shutter cameras showed time-integrated beam trajectories. These were digitized and compared to the gated camera images.