Scaled-Up Nonequilibrium Air Plasmas Generated by DC and Pulsed Discharges

摘要

The objective of the current program is to investigate the volume scalability of nonequilibrium plasmas produced by electrical discharges in atmospheric pressure air. Both DC and repetitively pulsed discharges have been successfully demonstrated to form non-equilibrium air plasmas at atmospheric pressure with temperatures below 2000 K and electron densities above 1012 cm-3. Such plasmas represent a potential for aircraft shielding, and many other applications, e.g. biodecontamination. The critical issues are the dimensions of these plasma discharges that are typically limited to cm-lengths and mmdiameters at maximum, and the power requirements. Key results demonstrate that both DC glow discharge and pulsed transient spark generate air plasmas of required parameters. Glow discharge is easier for volume scaling but requires larger power. Glow discharge operated in fast air flows preheated to 2000 K improves the volume scaling but at very high powers (including the preheating). The preheated air can be set below 2000 K at slower flows, thus enabling partial gas heating of the discharge. Corona discharge as a temperature probe was developed to diagnose the microwave torch preheated air.