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This paper describes experimental studies of the dependence of the X-ray intensity on the anode material in nanosecond high-voltage discharges. The discharges were generated by two nanosecond-pulse generators in atmospheric air with a highly inhomogeneous electric field by a tube-plate gap. The output pulse of the first generator (repetitive pulse generator) has a rise time of about 15 ns and a full width at half maximum of 30-40 ns. The output of the second generator (single pulse generator) has a rise time of about 0.3 ns and a full width at half maximum of 1 ns. The electrical characteristics and the X-ray emission of nanosecond-pulse discharge in atmospheric air are studied by the measurement of voltage-current waveforms, discharge images, X-ray count and dose. Our experimental results showed that the anode material rarely affects electrical characteristics, but it can significantly affect the X-ray density. Comparing the density of X-rays, it was shown that the highest x-rays density occurred in the diffuse discharge in repetitive pulse mode, then the spark discharge with a small air gap, and then the corona discharge with a large air gap, in which the X-ray density was the lowest. Therefore, it could be confirmed that the bremsstrahlung at the anode contributes to the X-ray emission from nanosecond-pulse discharges. [ABSTRACT FROM AUTHOR]

Pulsed power can provide instantaneously high power density to generate atmospheric nonthermal plasma in open air. In this paper, using two power supplies including a \(\mu \) s-pulse generator with a rise time of 300 ns and a pulsewidth of 5 \(\mu \) s and a ns-pulse generator of a rise time of 70 ns and a pulsewidth of 100 ns, pulsed gliding discharges are created with point-to-point electrodes in open air. Discharge images with these two generators under different flow rates are presented for a brief comparison of \(\mu \) s- and ns-pulse gliding discharges in air flow. [ABSTRACT FROM PUBLISHER]

The relation of desorbed gases and surface discharge in vacuum is a complex problem without reliable theory. The vacuum experimental platform of direct current and nanosecond pulse source was built, and the quadrupole mass spectrometer connected to vacuum cavity was used to analysis the out-gassing characteristics of insulation materials. Then the vacuum surface discharge experiments were done and the desorbed gases were measured in the process. By comparing the mass spectrum before discharges with ones after discharges, we obtained the out-gassing composition of several insulation materials. Meanwhile we analyzed the probable sources of different gases. Main gas components generated by vacuum surface flashover included H2O, N2, H2, O2, hydrocarbon fragment, CO, CO2 and sometimes high polymer fragment. C2H2 appeared in gas components when the filamentary discharge channel was formed between two electrodes. The results show that the high polymer surface may decompose and the dissolved gases may be extracted besides gas desorption in discharges. The discharge pattern has direct effect on their out-gassing characteristics. We'll thoroughly research their relation in subsequent work. [ABSTRACT FROM AUTHOR]

Nanosecond pulsed discharges have various discharge modes, such as corona, diffuse discharge, spark or arc. A dense diffuse discharge is particularly desirable for various applications at atmospheric pressure. In this paper, a magnetic-compression pulse generator was used to produce repetitive positive nanosecond pulses for excitation of a diffuse discharge. The output pulse of the generator had a rise time of about 25 ns and a full width at half maximum of 40 ns. Electrical characteristics of the diffuse discharge were studied by measuring its voltage and current waveforms, as well as images of the discharge. The conduction current was calculated by the measured voltage and current, which was a true discharge current. The experimental results show that a stable diffuse discharge could be obtained at atmospheric pressure, and the conduction current was unipolar and had similar amplitude of several amperes under our experimental condition, which has the similar amplitude with the displacement current. Furthermore, the air gap spacing and pulse repetition frequency (PRF) affected the intensity and mode transition of the diffuse discharge. The conduction current increased with the PRF but decreased with the air gap spacing. Therefore, the diffuse discharge was likely available under some conditions of proper air gap, high PRF with positive pulse. [ABSTRACT FROM AUTHOR]