Experimental status of the 100 MW Gyroklystron system at the University of Maryland

Abstract

Summary form only given. A test bed for implementation of first harmonic and second harmonic coaxial gyroklystrons is nearing its completion stages. This presentation includes the details of each major component's construction status as well as any relevant physical parameters. Designs of a fundamental frequency (8.568 GHz) and second-harmonic (17.136 GHz) microwave circuit have already been accomplished after selection among various two and three cavity designs. Predicted efficiencies near 40% for both these circuits using a large signal code have made them acceptable candidates for high power testing on the new test bed. The first harmonic circuit consists only of an input and output cavity while the second harmonic system has an additional buncher cavity situated between the input and output cavity to boost gain and efficiency up to 49 dB and 41% respectively. Cold testing of the constructed cavity parts are performed to verify their resonant frequency and Q with those predicted from our scattering matrix codes. These microwave circuits are ultimately studied using a 320 MW electron beam from the newly designed and constructed magnetron injection gun (MIG). Cold test results of the first harmonic output cavity indicate that its resonant frequency and Q are 8.568 GHz/spl plusmn/2 MHz and 134/spl plusmn/6 respectively. Because the input cavity's Q derives mostly from lossy properties introduced via ceramics, the required Q of 52 as dictated by the large signal codes are obtained purely from empirical methods during cold testing. The measured resonant frequency and Q of the input and buncher cavities along with descriptions and schematics of all these coaxial circuit cold test setups are presented.