Trapped-plasma-mode waveforms, circuit analysis, and harmonic generation

The operation of p⁺-n-n⁺silicon avalanche diodes with conversion efficiencies as high as 50 percent in the 0.9 to 1.7 GHz range is shown to be completely consistent with a trapped-plasma-mode explanation. Detailed sampling oscilloscope measurements of external current and waveforms have strongly substantiated Evans\´ analysis for the interaction between standard coaxial cavities and trapped-plasma-mode oscillators, and provided direct confirmation of the principal features of the trapped-plasma mode. The experimental waveforms indicated the presence of peak displacement currents prior to breakdown, that were on the order of 1.5 times the critical current ( ), required to launch a traveling avalanche zone. Approximately determined conduction-current waveforms exhibited larger currents during the shock front transit than during the extraction period. The terminal voltage during the extraction period was found to be near zero. The 4-GHz upper bound frequency and 1-GHz optimum frequency for the fundamental trapped-plasma mode were found to be consistent with the analytical calculations made by Cottam for diodes with doping and width similar to those studied and for waveforms similar to those observed.