Effect of driving frequency on electron heating in capacitively coupled RF argon glow discharges at low pressure

Abstract

A one-dimensional (1D) fluid model on capacitively coupled radio frequency (RF) argon glow discharge between parallel-plates electrodes at low pressure is established to test the effect of the driving frequency on electron heating. The model is solved numerically by a finite difference method. The numerical results show that the discharge process may be divided into three stages: the growing rapidly stage, the growing slowly stage, and the steady stage. In the steady stage, the maximal electron density increases as the driving frequency increases. The results show that the discharge region has three parts: the powered electrode sheath region, the bulk plasma region and the grounded electrode sheath region. In the growing rapidly stage (at 18 µs), the results of the cycle-averaged electric field, electron temperature, electron density, and electric potentials for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are compared, respectively. Furthermore, the results of cycle-averaged electron pressure cooling, electron ohmic heating, electron heating, and electron energy loss for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are discussed, respectively. It is also found that the effect of the cycle-averaged electron pressure cooling on the electrons is to "cool" the electrons; the effect of the electron ohmic heating on the electrons is always to "heat" the electrons; the effect of the cycle-averaged electron ohmic heating on the electrons is stronger than the effect of the cycle-averaged electron pressure cooling on the electrons in the discharge region except in the regions near the electrodes. Therefore, the effect of the cycle-averaged electron heating on the electrons is to "heat" the electrons in the discharge region except in the regions near the electrodes. However, in the regions near the electrodes, the effect of the cycle-averaged electron heating on the electron is to "cool" the electrons. Finally, the space distributions of the electron pressure cooling the electron ohmic heating and the electron heating at 1/4T , 2/4T , 3/4T , and 4/4T in one RF-cycle are presented and compared.

Effect of driving frequency on dust particle dynamics in radiofrequency capacitive argon discharge

“…The mathematical problem requires the resolution of the coupled system of (2.1)-(2.3) and (2.6) with a set of adequate boundary conditions. Here we have adopted the same boundary conditions that those used in previous papers (Lymberopoulos & Economou 1993;Samir et al 2017).…”

“…The initial conditions used in this work are similar to those given by Samir et al (2017) and Zhao et al (2018)…”

“…Many operating parameters can influence the discharge characteristics such as the gas pressure, the applied voltage, the gap between electrodes and the driving frequency, which is an important operating parameter in capacitive glow discharges. Thus, many researchers have studied the effect of the driving frequency on the discharge characteristics (Surendra & Graves 1991;Vahedi et al 1993;Colgan, Meyyappan & Murnick 1994;Heintz & Hieftje 1995;Kitajima et al 1998;Rakhimova et al 2006;Zhu et al 2007;Liu et al 2012;Huang & Gudmundsson 2014;Wilczek et al 2015;Sharma et al 2016;Samir et al 2017;Liu, Booth & Chabert 2018;Sharma et al 2018). These studies have shown a significant change in the discharge properties with a change in the driving frequency.…”

“…They found an increase in the ion density at the electrodes by a factor of approximately 4 and an increase in the electron density on space and time average by a factor of approximately 13 when the driving frequency increases from 59 to 60 MHz. Furthermore, Samir et al (2017) investigated the effect of driving frequency on the electron heating mechanism in capacitively coupled argon discharge, by using a fluid approach. They found a decrease in the sheath width as the driving frequency increases from 3.39 to 27.12 MHz.…”

“…Furthermore, Samir et al. (2017) investigated the effect of driving frequency on the electron heating mechanism in capacitively coupled argon discharge, by using a fluid approach. They found a decrease in the sheath width as the driving frequency increases from 3.39 to 27.12 MHz.…”