Using the basic moment equations (number density, how density, and energy d
ensity) for singly ionized argon and for electrons, a simple diffusion equa
tion (essentially one proposed by Lieberman and Lichtenberg) is adopted (by
comparison with experiment), together with an integrated power balance equ
ation. The effects of scaling magnetic field and radius are then discussed
first for simple cylinders, for which there are known analytic diffusion so
lutions. For specific cases having the more complicated geometry of two abu
tting coaxial cylinders with considerably different radii, the numerical re
sults are well approximated and delimited by considering only the wider cyl
inder for low magnetic field, and at high magnetic field, where end effects
dominate, using the total length and the smallest diameter of the system.