Theory of the collisional presheath in an oblique magnetic field

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870800· OSTI ID:6640383

Riemann, K ^[1]

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1. Institut fuer Theoretische Physik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

In the limit of a small Debye length ([lambda][sub D][r arrow]0), the plasma boundary layer in front of a negative absorbing wall is split up into a collision-free planar space charge sheath and a quasineutral presheath, where the ions are accelerated to ion sound speed (Bohm criterion). Usually the presheath mechanism depends decisively on collisional friction of the ions, on ionization, or on geometric ion current concentration. If the ion dynamics in the presheath is dominated by a magnetic field (nearly) parallel to the wall, an additional effect must be considered to provide an ion transport to the wall. The special cases (a) of an ion transport by field lines intersecting the wall at a finite angle and (b) of an ion transport by collisions result in somewhat contradictory conclusions. To get a coherent picture, a hydrodynamic model of the presheath is investigated accounting for an oblique magnetic field [ital and] for collisions. The limiting cases (a) and (b) are discussed, and it is shown that (in plane geometry) the presheath ion acceleration depends always on elementary processes. The main effect of a strong magnetic field is to compress'' the collisional presheath into a thin layer with a characteristic extension of the ion gyroradius [rho][sub [ital i]].

• OSTI ID: 6640383
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:3; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330 -- Plasma Kinetics
Transport
& Impurities-- (1992-)
700350* -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
BOHM CRITERION
BOUNDARY LAYERS
COLLISIONS
DEBYE LENGTH
DIMENSIONS
HYDRODYNAMIC MODEL
ION COLLISIONS
LAYERS
LENGTH
MAGNETIC FIELDS
MATHEMATICAL MODELS
PARTICLE MODELS
PLASMA SHEATH
SPACE CHARGE
STATISTICAL MODELS
THERMODYNAMIC MODEL
TRANSPORT THEORY