In this paper measurements of the behaviour of single microdischarges between metal and glass electrodes for both negative and positive polarities of the metal (designated and transitions, respectively), as well as the overall discharge behaviour between glass electrodes (GG), will be presented for different nitrogen - oxygen and water vapour - air mixtures. Increasing the oxygen concentration in nitrogen decreases the transferred charge per microdischarge for both polarities ( and ), while the total transferred charge per cycle is increased. With increasing water content in air, more charge is transferred per microdischarge for the polarity , but no significant change in the amount of transferred charge was found for a microdischarge. Less total charge is transferred per cycle with increasing water content. This is also true for double-dielectric barrier discharges (GG). The results suggest that water vapour coats the dielectric, reducing the surface resistance and increasing the effective dielectric capacity. This mechanism is supported by analysis of the voltage versus charge plot (Lissajous figure) for the involved capacitances of a double-barrier discharge. The reduction of the surface resistance of the dielectric and the resulting increase in the effective dielectric capacitance, are shown by photographs of spatially isolated microdischarges in a metal - pin dielectric arrangement.

Plasma destruction of toxins, and volatile organic compounds in particular, from gas streams is receiving increased attention as an energy efficient means to remediate those compounds. In this regard, remediation of trichloroethylene (TCE) in silent discharge plasmas has been experimentally and theoretically investigated. We found that TCE can be removed from Ar/OZ gas streams at atmospheric pressure with an energy efficiency of 15-20 ppm/(mJ/cm3), or 2-3 kW h kg-'. The majority of the Cl from TCE is converted to HCl, Cl,, and COCl*, which can be removed from the gas stream by a water bubbler. The destruction efficiency of TCE is smaller in humid mixtures compared to dry mixtures due to interception of reactive intermediates by OH radicals.

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Described here is the design and construction of a pulse-power generator capable of discharging at high repetition rates. It consists of eight triaxial Blumleins stacked in series at one end. These lines are charged in parallel and synchronously commuted with a single thyratron at the other end to produce an open circuit voltage across a stack of six times the charging voltage. An x-ray diode has been constructed and matched to this pulse-power source making possible the emission of an average bremsstrahlung exposure rate of 17 R/S from a sequence of 40-ns pulses. When operated at 60-kV charging voltage, direct spectral measurements show the output to be a true continuum, peaking at intensities in excess of 5×108 photons/keV/shot and containing useful intensities of photons having energies of 300 keV.