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Collisional transport treatment of surface plasma structures

Journal Article · · Phys Fluids B; (United States)
DOI:https://doi.org/10.1063/1.858923· OSTI ID:5823276

Calculations are shown of the structure of plasmas in equilibrium with solid surfaces that reemit incident plasma ions as relatively cold neutral gas. A numerical transport model that includes a Fokker--Planck treatment of ion--ion collisions obtains the distribution function for ions in a phase space of one spatial coordinate and two velocities. This is done self-consistently with an electrostatic potential, a Maxwell--Boltzmann description of electrons, and electron impact ionization of the reemited neutrals. Solutions are obtained from a higher temperature kinetic regime where Coulomb collisions are nearly negligible to a lower temperature regime where plasma behavior is approximately fluidlike. A result of these calculations is the resolution of an ambiguity posed by previous kinetic regime calculations that omitted ion--ion collisions and obtained a family of solutions for each set of physical parameters (Phys. Rev. Lett. /bold 49/, 650 (1982); Phys. Fluids B /bold 1/, 448 (1989)). The physically correct solution for semi-infinite surface plasmas is shown to be the member of each family that maximizes the ion thermal conduction to the surface and the magnitude of a maximum in the electrostatic potential that is found in these and the previous calculations. Further results are in agreement at lower temperatures with solutions obtained from a fluid model and the identification of the correct boundary condition on normal flow velocity to be used in fluid models.

Research Organization:
Los Alamos National Laboratory, X-1, E531, Los Alamos, New Mexico 87545 (US)
OSTI ID:
5823276
Journal Information:
Phys Fluids B; (United States), Journal Name: Phys Fluids B; (United States) Vol. 1:9; ISSN PFBPE
Country of Publication:
United States
Language:
English