Fundamental issues in fluid modeling: direct substitution and aliasing methods.

It is shown how the accuracy of fluid models of charged particles in gases can be improved significantly by direct substitution of swarm transport coefficient data, rather than cross sections, into the average collision terms. This direct substitution method emerges in a natural way for fluid formulations in which the role of the mean energy is transparent, whatever the mass of the charged particles in equation (ions or electrons), and requires no further approximations. The procedure is illustrated by numerical examples for electrons, including the operational window of E/N for an idealized Franck-Hertz experiment.

Fluid-model analysis of electron swarms in a space-varying field: nonlocality and resonance phenomena.

The physically based, benchmarked fluid model developed by Robson et al. [R. E.

Double-layer formation in the extended Franck-Hertz experiment.

A model is developed which explains the collective plasma phenomena associated with the extended Franck-Hertz experiment described in an earlier paper by Nicoletopoulos [Eur. J. Phys.

Periodic electron structures in gases: a fluid model of the "window" phenomenon.

Periodic electron spatial structures in gases occur within a window of voltages and pressures. Recent accurate solutions of Boltzmann's equation portray this effect, but offer little physical insight into the causes of windowing. Here we show for the first time how such insight can be obtained using the fluid model established by Robson, White, and Petrović [Rev.