Thermal Effects of Low-Pressure Glow Discharge and Its Heat Transfer Through the Discharge Tube

The light emitted by gas discharge plasma is often used as a light source for precision optical instruments. The measurement precision and accuracy of these precision instruments are greatly affected by the ambient temperature. In fact, although low-pressure glow gas discharge plasma is often referred to as "low-temperature plasma", it may also have thermal effects under prolonged operation. There is a lack of research on the thermal effects of low-pressure glow discharges and the process of its heat transfer through the discharge tube. In this article, a 2-D axisymmetric fluid model is established, coupling multiphysics fields such as discharge plasma, laminar flow, and heat transfer. The thermal effect and heat transfer of He/Ne gas mixture glow discharge at low pressure are investigated. Studies show that, after the discharge has lasted for a certain period of time, the temperature in the gas discharge region is significantly elevated and can reach tens or hundreds of kelvins. The temperature of the glass tube may also increase by more than 20 K under certain discharge parameters. The current-limiting resistance, the gas pressure, and the He/Ne gas ratio have a large influence on the thermal effect of the gas discharge. Therefore, the thermal effect of gas discharge applied as a light source in precision optical instruments cannot be ignored and needs to be regulated and designed for specific situations. This article contributes to a deeper physical understanding of the thermal effects of low-pressure glow discharges and provides guidance for their optical application.