Rapid formation of distributed plasma discharges using X-band microwaves

Summary form only given. Preliminary observations of rapidly formed (<;50 ns) distributed plasma discharges using X-band microwaves are presented. The following setup establishes the conditions necessary to study complex microwave discharges. The microwave discharge test chamber is an L-band brass rectangular waveguide with polycarbonate windows. The chamber is illuminated by the output of 25 kW, 0.8 μs pulse-width, 9.382 GHz magnetron through an X-band waveguide pressed against the chamber´s polycarbonate window. The chamber is filled with Ne, Ar, or a mixture to create a Penning discharge. Isolation between incident and reflected ports is achieved with an X-band circulator and the incident power is varied using a circulator, an E-H tuner, and matched load. Measured incident, reflected, and transmitted microwave power arising from the plasma provide discharge breakdown characteristics and attenuation characterization at pressures between 10 and 760 torr. Observations of localized transmission spike measurements of -20 dB that occur within 50 ns caused by the plasma have been made. Additionally, a 12.5 GHz continuous wave source permits measurement of breakdown and plasma decay. A photomultiplier tube sensitive from 128nm-850nm allows observation of plasma formation. Also, an ICCD provides fast time-scale images of the plasma. Plasma modeling using reflection and transmission coefficients based on plasma properties allows for experimental data results to be compared with theoretical behavior.