Plasma Switch for High-Power Active Pulse Compressor

60059 A previously built Active Bragg Compressor (ABC) had been shown capable of rapid switching of 11.4 GHz microwave energy stored in a resonant cavity, in order to produce a compressed 50-100 nsec pulse with a peak power gain of 10-12. However, the peak output power in the ABC was limited to about 100 MW due to spontaneous breakdown of the switch. This project will develop a modified plasma switch to produce 500-700 NW output pulses, based on switch configurations for ABC that utilize resonators containing one or more discharge tubes, which alter the resonator transmission coefficient upon firing. This allows the discharge tubes to reside, during the filling time of the compressor storage cavity, in an rf electric field that is less than one-third that of the initial ABC. In Phase I, several designs for resonance plasma switches with self-breakdown characteristics superior to earlier models have been developed. Numerical analysis was applied to each design to simulate operation. Non-high-vacuum prototypes were fabricated, and measurements were made of their characteristics at low power level. The measurements showed compression ratios in the range 10-15, stability of +0.3¿ in relative input-to-output phase variations, three-fold reduction in electric field at the switch, and energy efficiency in the range of 60-65%. High-power tests will be conducted during Phase II, using output from an 11.4 GHz magnicon, to produce 500-700 peak power compressed pulses with compression ratios >10:1 and energy efficiencies >60%. Commercial Applications and Other Benefits as described by the awardee: Thousands of rf pulse compressors could be required for Next Linear Collider, and these high-compression-ratio active compressors should be serious candidates for this application. The value of this commercial market is in the range of $10 - $20 million. Other applications of high-power, high-compression-ratio, active rf pulse compressors include industrial accelerators and short-pulse radars.