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Author(s):
K. Sato, H. Katayama and F. Miyawaki
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Title:
Electrostatic Potential in a Collisionless Plasma Flow Along Open Magnetic Field Lines
Date of publication:
June 1992
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Key words:
open magnetic field, collisionless plasma, electrostatic potential, magnetic throat, generalized Bohm criterion, trapped electron
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Abstract:
Formation of the steady-state potential in a collisionless plasma flow along nonuniform magnetic field lines terminated at a wall is studied theoretically under the condition that a particle source in a plasma can be neglected. It is found that the plasma flow is required to satisfy the generalized Bohm criterion over the whole region for the formation of the steady-state continuous potential in the divergent magnetic field. A monotonically falling potential can build up from the inside of the magnetic throat to the wall only if the Bohm criterion is marginally satisfied at the throat. Numerical solutions to Poisson's equation show that a potential profile outside the throat is strongly dependent upon the particle densrty of electrons trapped between the throat and the wall. Controllability of the potential by increasing the trapped-electron density is discussed briefly.
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