The influence of gas pressure, voltage and frequency on plasma propagation in tube

Abstract

The influence of gas pressure and electrical parameters on low pressure plasma in tube has been investigated. The gas pressure has a great influence on both the length of the plasma and the propagation velocity of the plasma bullet. Both the length of plasma jet and the velocity of plasma bullet increase firstly and then decreases with the increase of gas pressure from 15 Pa to 15000 Pa. The plasma length achieves maximum at 100 Pa with a propagation velocity about 5×106 m/s. Relative to voltage, the frequency of applied pulse voltage has different impact on the plasma propagation at different gas pressure. While higher voltage induces longer plasma and faster propagation velocity at both 30 Pa and 2000 Pa, increasing frequency has little influence on plasma at 30 Pa but reduces the plasma length and propagation velocity observably at 2000 Pa. In addition, an exotic plasma plume structure is observed by a fast intensified charge-coupled device (ICCD). A possible hypothesis is discussed here to explain this phenomenon. These works may lead to a more precise controlling of low pressure plasma, warranted for advanced materials technologies.