On the Feasibility of MIcrowave Produced Bragg Reflector: Examined by the Chamber Experiment
POLYTECHNIC UNIV FARMINGDALE NY WEBER RESEARCH INST
Pagination or Media Count:
A set of parallel plasma layers is generated by two intersecting microwave pulses in a chamber containing dry air at a pressure comparable to the upper atmosphere. The dependencies of breakdown conditions on the pressure and pulse length are examined. The results are shown to be consistent with the appearance of tail erosion of microwave pulse caused by air breakdown. A Bragg scattering experiment, using the plasma layers as a Bragg reflector is then performed. Both time domain and frequency domain measurements of wave scattering are conducted. The experiment results are found to agree very well with the theory. Moreover, the time domain measurement of wave scattering provides an unambiguous way for determining the temporal evolution of electron density during the first 100 microsecond period. A Langmuir double probe is also used to determine the decay rate of electron density during a later time interval 1 ms to 1.1 ms. The propagation of high power microwave pulses through the air is also studied experimentally. The mechanisms responsible for two different degree of tail erosion have been identified. The optimum amplitude of an 1.1 microsecond pulse for maximum energy transfer through the air has been determined.
- Plasma Physics and Magnetohydrodynamics