PASOTRON{trademark} amplifier experiments

Preliminary experimental studies are reported of an L-Band amplifier based on Hughes` Plasma-Assisted, Slow-Wave Oscillator (PASOTRON) technology. The amplifier system utilizes a hollow-cathode-plasma electron-gun, and a plasma-filled Slow-Wave Structure (SWS) to produce {>=} 100-{micro}sec-long, 50 to 75-kV, 30 to 100-A electron-beam pulses that propagate in a plasma channel without the use of any externally applied axial magnetic field. The electron-beam pulse coincides with a 100-{micro}sec-long RF drive signal provided by a 2.6-kW TWT, which is coupled into the amplifier upstream of the SWS. The SWS consists of a ring-bar design which is novel to the PASOTRON family of devices and is used for its short length compared to a helix. Simulations on HP`s High Frequency Structure Simulator were used to optimize the ring-bar SWS. Preliminary data are reported showing the new L-Band amplifiers gain, power, efficiency, and bandwidth. Methods of eliminating a Backward Wave Oscillation (BWO), which was found to limit the performance of the tube, are also presented.