The DC atmospheric barrier plasma discharge-recent results

Summary form only given. We have been generating intense, steady-state, DC discharges in air and other gases, notably helium. The discharge appears to fill the chamber volume uniformly, without sparks or striations. The basic improvement that prevents the discharge from contracting into a spark or an arc is an unglazed ceramic plate that has been moistened with water to make it into a semiconductor (patent pending). With this improvement, we have put up to 300 Watts of steady-state DC power (30 KV at 10 mA-the power supply limit) into about a litre of helium plasma at atmospheric pressure. The discharge also works well in atmospheric pressure air, although the gap between the discharge electrodes must be reduced. The system has run for over 30 minutes with no problems. The system also works well on 60 Hz. AC from a simple transformer, such as that used for neon signs. For diagnostics, we have developed an apparently new diagnostic probe, the diffusion probe, that is useful in the DC or low-frequency AC regimes where ion and electron motion is diffusive, rather than ballistic, as is the case for the Langmuir Probe. With this probe, we have measured plasma ion densities of over 10 exp. 12 per cc.