Electrical characteristics of a millisecond pulsed glow discharge

A mu s and ms pulsed argon glow discharge was investigated with respect to the breakdown condition (Paschen curve). Moreover, current-voltage profiles were acquired for different discharge frequencies, pulse durations, cathode-anode spacing and discharge pressures. The breakdown voltage was dependent on the cathode material (Cu, steel, Ti and Al). No severe change in the breakdown voltage was observed for a I ms pulse at different frequencies. However, the theoretical breakdown curve, calculated based on the Paschen equation did not fit the experimental data. The current plots for different cathode-anode spacing showed a maximum at intermediate distance (8-10 mm). These data were consistent with mass spectrometric data acquired using the same instrument in a GC-GD-TOFMS chemical speciation study. A higher discharge frequency with constant pulse duration leads to an increase in discharge current, probably due to a more dense plasma during the pulse. This is supported by the total emission of the plasma, which was not reaching the baseline for short delays in-between the plasma pulses. In addition, the total emission of the plasma shows that at least 2 ms is needed for the plasma to reach a stable quasi steady-state. The current-voltage (traces) for different discharge pressures show a constant relationship for different pulse durations. The current-voltage relation is pressure dependent and similar to dc-glow discharges. A fast photodiode was used for precise observation of the entire Penning ionization in the afterpeak at different pressure settings. (c) 2008 Elsevier B.V. All rights reserved.