Fluidlike studies of the sheath and presheath regions of a plasma
We investigate the problem of a collisional plasma flowing into a perfectly absorbing wall. Both the collisional presheath and the collisionless sheath regions are modelled by fluid-like moment equations that are derived from kinetic theory. Previous work was based primarily on a collisionless kinetic theory or collisional Braginskii equations which have singularities at the sheath edge. The electron distribution function is obtained here from the solution of a Pastukhov type problem instead of a simple Boltzmann relation. For the ions a kinetic theory is required to determine the ion viscous stress tensor and heat flux because the collisional mean free path is comparable to the characteristic gradient scale length in the presheath region. A boundary layer analysis is applied for determining the distribution function of the ions in the velocity space region corresponding to no net return flux from the wall. This analysis provides a continuous solution over the entire region of interest. The viscous force deduced from this distribution function, which is a cutoff Maxwellian relaxed by collisions, is comparable to the electric field force everywhere and removes the singularity between the presheath and the sheath regions in the ion momentum equation. The total heat flux obtained using the same method as for the viscous force removes the singularity in the ion energy conservation equation. Four different numerical calculation cases are presented in this thesis.
- Research Organization:
- Wisconsin Univ., Madison, WI (United States)
- OSTI ID:
- 7057575
- Resource Relation:
- Other Information: Ph.D. Thesis
- Country of Publication:
- United States
- Language:
- English
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Fluidlike studies of the presheath and sheath regions of a plasma
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COLLISIONAL PLASMA
BOUNDARY LAYERS
ELECTRONS
WALLS
ABSORPTION
DISTRIBUTION FUNCTIONS
ELECTRIC FIELDS
HEAT FLUX
KINETIC EQUATIONS
MEAN FREE PATH
PLASMA
PLASMA SHEATH
TENSORS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FUNCTIONS
LAYERS
LEPTONS
SORPTION
665000* - Physics of Condensed Matter- (1992-)