  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.
