Predicted Properties of Cylindrical Microhollow Cathode Discharges in Helium Using a Two‐Dimensional, Self‐Consistent Fluid Model

Abstract

In this paper, a numerical simulation model was developed to simulate the helium plasma in a cylindrical Microhollow cathode based on a two-dimensional, time-dependent and self-consistent fluid model. The aim of our work is to provide estimates of the main discharge and plasma parameters and to help understand the basic mechanisms governing the MHCD devices. Accurate solutions of the continuity equations, electron energy balance equation and possion's equation with realistic boundary conditions are obtained. Realistic discharge characteristics are simulated, which are very important to understand the phenomena of microhollow cathode discharge (MHCD). The results show that there exists a hollow cathode effect in the discharge process. He electric field is mainly a radial field close to the cathode in the discharge area. The influences of gas pressure and cathode dimension on discharge characteristics were also investigated.

Numerical study on rectangular microhollow cathode discharge

“…For example, Boeuf and Pitchford 7 used a fluid model to calculated current-voltage ͑I-V͒ characteristics of a sandwich type of MHCD. Gu et al 8 used a two-dimensional ͑2D͒ selfconsistent fluid model to predict the discharge properties of cylindrical MHCD. In the past, most researches focused on the cylindrical structure, while few works have been done on the rectangular MHCD, although it has also wide potential applications in laser, coating, etc.…”

A simulation study of the self-pulsing regime of a micro hollow cathode discharge in helium using a zero-dimensional model

“…Therefore, numerical modelings are widely used to study these discharges. Several research works have employed fluid models to simulate MHCDs and discover their basic principles [27][28][29]. They found that MHCDs consist of two main regions: cathode fall (CF) and negative glow (NG).…”

“…Due to the small distance between the anode and cathode in MHCDs, no significant positive column is formed. Then, the ions generated in the NG are accelerated by the electric field and their density increases toward the cathode, reaches its maximum in the cathode sheath, and then collide with the cathode surface and emit secondary electrons [28]. These electrons are accelerated in the sheath strong field and then spend their energies by exciting the ground-state atoms.…”

“…Some of these electrons can move opposite to the sheath field and participate in ionization collisions. This oscillatory motion of the electrons, known as the 'pendulum effect', is one of the most effective factors in enhancing the MHCDs densities compared to other non-thermal discharges [28].…”

Simulation of Electron Motion in a Micro-Hollow Cathode Discharge

“…Thereinto, fluid models are founded on the numerical solution of Poisson equation, and they may cause computing errors originating from the non-equilibrium characters and nonlocal effects. And compared with the computationally demanding and time-consuming PIC/MCC (a hybrid of particle-in-cell and Monte Carlo collision) models, Monte Carlo technique is an accurate and straightforward statistical method to simulate the acting force and transient motion of electrons and ions in the cathode sheath and negative glow region [5,6].…”