Advanced fluid modelling and PIC/MCC simulations of low-pressure ccrf discharges

TL;DR

This study compares fluid models and PIC/MCC simulations for low-pressure helium and argon discharges, demonstrating the improved accuracy of a new fluid model with an advanced drift-diffusion approximation over classical methods.

Contribution

It introduces and validates a novel fluid model with an enhanced drift-diffusion approach, showing better agreement with kinetic simulations at low pressures.

Findings

The new fluid model aligns well with PIC/MCC results across various conditions.

Two independent PIC/MCC codes show excellent agreement, confirming simulation accuracy.

The classical drift-diffusion approach often fails where the new model succeeds.

Abstract

Comparative studies of capacitively coupled radio-frequency discharges in helium and argon at pressures between 10 and 80 Pa are presented applying two different fluid modelling approaches as well as two independently developed particle-in-cell/Monte Carlo collision (PIC/MCC) codes. The focus is on the analysis of the range of applicability of a recently proposed fluid model including an improved drift-diffusion approximation for the electron component as well as its comparison with fluid modelling results using the classical drift-diffusion approximation and benchmark results obtained by PIC/MCC simulations. Main features of this time- and space-dependent fluid model are given. It is found that the novel approach shows generally quite good agreement with the macroscopic properties derived by the kinetic simulations and is largely able to characterize qualitatively and quantitatively the discharge behaviour even at conditions when the classical fluid modelling approach fails. Furthermore, the excellent agreement between the two PIC/MCC simulation codes using the velocity Verlet method for the integration of the equations of motion verifies their accuracy and applicability.