Air-breakdown limits for microwave-pulse propagation. Part I. Experiments
We have measured breakdown power levels for short pulses of 2.856-GHz microwaves in a test section of WR-284 waveguide filled with air at several pressures in a range extending from 0.1 Torr to several hundred Torr. The traveling wave input to the test section was a pulse with a risetime of approximately 50 nonoseconds, a length of 100 ns (fwhm), and an amplitude of approximately 15 MW. Input power to the test cell and transmitted power were monitored with directional couplers and fast diodes: reflected power was also monitored on some measurements. Breakdown power for a given air pressure is defined as the power level (generally on the leading edge of the pulse) at which extreme attenuation of the transmitted pulse occurs. Although the present results must be considered preliminary, they are presented here because they are the only single-pulse microwave data that exist for pulse lengths below 100 ns. The data are compared with predictions of simple cascade theory, existing microwave breakdown data, video-pulse breakdown data, and recent LLNL fluid-model predictions.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA); EM Design, Dublin, CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5706285
- Report Number(s):
- UCID-19877-Pt.1; ON: DE83017832
- Country of Publication:
- United States
- Language:
- English
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