Theory of cylindrical and spherical Langmuir probes in the limit of vanishing Debye number

Journal Article · Wed Dec 01 04:00:00 EST 1982 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.863725· OSTI ID:6898228

Parrot, M J.M.; Storey, L R.O.; Parker, L W; Laframboise, J G

A theory has been developed for cylindrical and spherical probes and other collectors in collisionless plasmas, in the limit where the ratio of Debye length to probe radius (the Debye number lambda/sub D/) vanishes. Results are presented for the case of equal electron and ion temperatures. On the scale of the probe radius, the distributions of potential and density in the presheath appear to have infinite slope at the probe surface. The dimensionless current--voltage characteristic is the same for the cylinder as for the sphere, within the limits of error of the numerical results, although no physical reason for this is evident. As the magnitude of probe potential (relative to space) increases, the current does not saturate abruptly but only asymptotically; its limiting value is about 45% larger than at space potential. Probe currents for small nonzero lambda/sub D/ approach those for zero lambda/sub D/ only very slowly, showing power-law behavior as function of lambda/sub D/ in the limit as lambda/sub D/ ..-->.. 0, with power-law exponents less than unity, resulting in infinite limiting derivatives with respect to lambda/sub D/.

• Research Organization: Centre National de la Recherche Scientifique, Centre de Recherches en Physique de l'Environnement, 45100 Orleans, France
• OSTI ID: 6898228
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 25:12; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
ANALYTICAL SOLUTION
BOLTZMANN STATISTICS
COLLISIONLESS PLASMA
CONFIGURATION
CYLINDRICAL CONFIGURATION
DEBYE LENGTH
DIMENSIONS
ELECTRIC PROBES
LANGMUIR PROBE
LENGTH
PLASMA
PROBES
SPHERICAL CONFIGURATION