GE REDUCED PROBLEM WITH DIFFERENT INITIAL CONDITIONS 1


The reduced problem is from Lawler & Kortshagen, J. Phys D: Appl Phys 32, pp 3188-3198 (1999), "Self-consistent Monte Carlo simulations of the positive column of gas discharges." The reduced problem using the Lawler and Kortshagen cross-sectional data was run on a 600 MHz Pentium III machine with 1/2 the initial density of the previous run in Reduced Problem with L&K X-secs

The simulation starts off with initial Bessel function electron and ion density profiles with axial density = 8.2e8/cc. The following is a link to the input file: Input File.

The simulation was run for 45 microsecs. Equilibrium was reached at about 5 microsecs as can seen from the Average Density(t) and Ez(t) diagnostics below. Halving the initial density had no effect on the convergence or the overall time to equilibrium. Again, agreement is good between the expected and XPDC1 output.

INPUTS
Gas is argon with model cross sections (one lumped excited state) R=1 cm
Gas temperature = 273K
Gas pressure = 2.83 mTorr (2.83e-3 Torr)
Gas density = 1e14/cc (important!)
Axial current = 15.2 mA

EXPECTED OUTPUT (from Lawler and Kortshagen paper)
Ez=1.0 V/cm (from Table 1)
Electron average energy on axis = 14.7 V (from Table 1)
Electron density on axis = 1.64e9/cc (from Table 1)
Wall potential = 37 V (by inspection of Figure 1)

XPDC1 OUTPUT
Ez=0.74 V/cm
Electron average energy on axis = 13.5 V
Electron density on axis = 1.6e9/cc
Wall potential = 32 V