A kinetic simulation study of glow discharges within millimeter-scale hollow anode

This paper presents a numerical simulation of DC glow discharge at 2 Torr (1 Torr = 1.33322×10² Pa) with a microhollow anode, using a two-dimensional (2D) PIC/MCC code to explore the impact of the hollow anode structure on discharge characteristics. Simulation results show that the plasma density in the anode channel decreases exponentially along the x-direction towards the outlet while the electric potential decreases linearly. The electron temperature, derived from the relationship between density and electric potential, shows a good agreement with the calculated temperature. The potential peak at the inlet, along with the grounded anode, forms a transverse potential well that draws electrons toward the center of the channel. The x-direction electric field, generated by the potential difference between the inlet and outlet of the anode, directs electrons toward the inlet of the anode. Low-energy electrons are confined within the potential well, while very few high-energy electrons outlet the channel. The hollow anode structure serves as a collimator for electrons, leading to an increment of moderate-velocity electron flux in the anode channel. Shortening the anode leads to a slower rate of density decrease, resulting in a higher density at the outlet.