Status of the Choppertron experiments

The Choppertron is a high-power, 11.4 GHz microwave generator driven by a linear induction accelerator (LIA). Earlier work with the Choppertron using a 2.5 MV, 1 kA beam demonstrated both high power and quality (phase and amplitude stability) microwave pulses. Significant effort was expended on suppressing pulse shortening caused by excitation of higher order modes. A new series of experiments are coming on-line using a 5 MV, 1 kA LIA beam to drive an upgraded Choppertron. In this paper we review the performance of the Choppertron at 2.5 MV including observed pulse shortening and describe the current status of the experiments. We discuss proposed experiments including reacceleration, active phase stabilization, and high-power microwave extraction. (Author) 4 figs., 5 refs