- Semi-implicit Monte Carlo techniques exist
for solving coupled,

nonlinear radiation transport equations [Larsen, 1987], - Could adapt to our coupled, nonlinear problem.
- Basic idea already in use for some parts:
- Charge exchange,
- If truly explicit, CX treated in MC code as separate sink & source,
- Source neutrals would be newly chosen from background,
- Effect on plasma would match prior neutral
sink only on average

additional noise in fluid equations, - Instead, we treat both halves of CX as one consistent process,
- E.g., plasma particle source ( for single species)
exactly right

for any number of flights.

- BGK simulation of neutral-neutral interaction
- See, e.g., [Reiter, 1997],
- ``Test'' neutrals elastically collide with background of neutrals

described as sum of Maxwellians, - Just as in CX case, treating collisions as single process makes problem more implicit.

- Charge exchange,
- Could we do something analogous for ionization and recombination?
- Presently treated as distinct sink and source processes,
- Could they be combined?

- What about ionization and plate recycling?
- Because of its flexibility, DEGAS 2 could be readily adapted to use such new methods.
- Study will continue in parallel with explicit coupling work.

Wed Nov 26 10:29:07 EST 1997