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A nonthermal plasma with an electron density on the order of [10.sup.12] [cm.sup.-3] and a gas temperature of 2000 K was generated in atmospheric pressure air, using a microhollow cathode discharge as plasma cathode. The plasma was sustained in a ~1 [mm.sup.3] micro reactor, by a voltage of 470 V between the plasma cathode and a planar anode, and at currents ranging from 12 to 22 mA. This direct current glow discharge has been used to study the remediation of methane and benzene, two of the most stable volatile organic compounds (VOCs). The removal fraction for 300-ppm methane in atmospheric pressure air, flowing through the 0.5-mm thick plasma layer, with a residence time of the gas in the plasma of less than 0.5 ms, was measured at 80% with an energy density of 4 kJ/L. For benzene, the remediation rate is as high as 90%, comparable to results obtained with low pressure glow discharges. The energy efficiency for benzene remediation is 0.9 g/kWh, higher than that obtained for benzene remediation in low pressure glow discharges in noble gases. However, the VOC fraction remaining was found to be limited to values of approximately 0.1 and 0.05 for methane and benzene, respectively. In addition to experimental studies, the VOC dissociation mechanism in a VOC/dry air mixture plasma was modeled using a zero-dimensional plasma chemistry code. The modeling results have shown that atomic oxygen impact reactions are the dominant dissociation reactions for VOC destruction in this kind of glow discharge. Diffusion of atomic oxygen to the dielectric walls of the reactor is assumed to cause the observed limitation in the VOC destruction rate and efficiency. Index Terms--Atmospheric pressure air, chemical decontamination, glow discharge, nonthermal plasma, volatile organic compounds.

The possibility to control functions and membrane transport processes in biological cells by external pulsed electric fields offers new applications for pulsed power technology. One such application is prevention of biofouling, an effect that is based on reversible electroporation of cell membranes. Pulsed electric fields of several kilovolts per centimeter amplitude and submicrosecond duration have been found to prevent the growth of aquatic nuisance species on surfaces. Reversible electroporation is also used for medical applications, e.g., for delivery of chemotherapeutic drugs into tumor cells, for gene therapy and for transdermal drug delivery. Higher electric fields cause irreversible membrane damage. Pulses in the microsecond range with electric field intensities in the tens of kilovolts per centimeter are used for bacterial decontamination of water and liquid food. A new type of field-cell interaction utilizing nanosecond pulses with electric fields exceeding 50 kV/cm has been recently added to known bioelectric effects. Based on capacitive coupling to cell substructures, it has the potential to affect transport processes across subcellular membranes and may be used for gene transfer into cell nuclei. Other studies indicate that it triggers intracellular processes such as programmed cell death that can be used for cancer treatment. In order to generate the required electric fields for these processes, high-voltage high-current sources are required. The pulse duration needs to be short to prevent thermal effects. Pulse power technology is the enabling technology for this new field of bioengineering, which we have termed 'bioelectrics.' Index Terms--Electroporation, pulsed electric field methods, subcellular effects.

Pulse power technology using high intensity (up to 300 kV/cm) nanosecond pulsed electric fields (nsPEF) has been applied for decontamination and amelioration of biofouling, but until now effects on human cells have not been investigated. To analyze structural and functional changes in human cells and solid tumors following exposure to nsPEF, we utilized flow cytometry and immunofluorescence microscopy. We provide further support for the hypothesis that as the pulse duration is decreased, there is a lower incidence of electric field interactions at the plasma membrane and a higher incidence of interactions with intracellular structures. The nsPEF effects are pulse duration/electric field intensity-dependent and energy density- or temperature-independent. We also show that nsPEF induces programmed cell death (apoptosis) in cultured cells as indicated by cell shrinkage, Annexin-V-FITC binding to phosphatidylserine on intact cells, and caspase activation. Mouse fibrosarcoma tumors exposed to nsPEF exhibit fragmented DNA and reduced tumor growth in a mouse model. These studies show that nsPEF effects are distinctly different than electroporation pulses and provide the first evidence for the potential application of nsPEF to induce apoptosis and inhibit tumor growth. Index Terms--Annexin-V-FITC, apoptosis, caspases, fibrosarcoma, flow cytometry, HL-60 cells, Jurkat cells, nanosecond pulsed electric fields.

Electron heating was studied in atmospheric pressure glow discharges.

Series operation of direct current xenon chloride excimer sources is investigated.

Research was conducted to examine the stabilization and control of a high-pressure glow discharge using a microhollow cathode discharge. It was possible to produce stable, direct current discharges in argon up to atmospheric pressure with the use of microhollow cathod discharge as plasma cathode. Results demonstrate the potential of the method for the production of large volume plasmas at high gas pressure by means of superposition of individual glow discharges.

Increasing the current of a microhollow cathode discharge in high-pressure xenon allowed us to generate disc-shaped 100- to 150-[micro]m-thick plasma layers on the planar cathode of a microhollow electrode system, with diameters approaching 1 cm. The plasma layer has been found to emit intense excimer radiation at 172 nm. The maximum of the excimer emission shifts with increased current toward the perimeter of the plasma disc, and the spectral distribution in the area close to the cathode hole changes from vacuum ultraviolet to visible. Plasma filaments, radiating in the visible, are formed which extend from the center to the perimeter of the disc shaped plasma. They correspond to areas of reduced excimer emission, indicating a transition from nonthermal to thermal plasma. Index Terms--Excimer radiation, glow discharge, ultraviolet.

Parallel operation of dc microhollow cathode discharges in argon at pressures up to several hundred torr was obtained without individual ballast at low currents, where the slope of the current-voltage characteristic is positive. By using semi-insulating silicon as anode material, we were able to extend the range of stable operation over the entire current range, including that with negative differential resistance. This opens the possibility to utilize microhollow cathode discharge arrays in flat panel lamps. Index Terms - Gas discharges, glow discharges, light sources.

A nonthermal plasma with an electron density on the order of 1012 cm-3 and a gas temperature of 2000 K was generated in atmospheric pressure air, using a microhollow cathode discharge as plasma cathode. The plasma was sustained in a ∼1 mm³ micro reactor, by a voltage of 470 V between the plasma cathode and a planar anode, and at currents ranging from 12 to 22 mA. This direct current glow discharge has been used to study the remediation of methane and benzene, two of the most stable volatile organic compounds (VOCs). The removal fraction for 300-ppm methane in atmospheric pressure air, flowing through the 0.5-mm thick plasma layer, with a residence time of the gas in the plasma of less than 0.5 ms, was measured at 80% with an energy density of 4 kJ/L. For benzene, the remediation rate is as high as 90%, comparable to results obtained with low pressure glow discharges. The energy efficiency for benzene remediation is 0.9 g/kWh, higher than that obtained for benzene remediation in low pressure glow discharges in noble gases. However, the VOC fraction remaining was found to be limited to values of approximately 0.1 and 0.05 for methane and benzene, respectively. In addition to experimental studies, the VOC dissociation mechanism in a VOC/dry air mixture plasma was modeled using a zero-dimensional plasma chemistry code. The modeling results have shown that atomic oxygen impact reactions are the dominant dissociation reactions for VOC destruction in this kind of glow discharge. Diffusion of atomic oxygen to the dielectric walls of the reactor is assumed to cause the observed limitation in the VOC destruction rate and efficiency. [ABSTRACT FROM AUTHOR]