Spreading of a small inhomogeneity in an unbounded, weakly ionized plasma in a magnetic field
The problem of the spreading of a small inhomogeneity (deltan very-much-less-thann/sub 0/, where n/sub 0/ is the density of the unperturbed plasma) of a weakly ionized plasma in a magnetic field is solved in the quasineutral approximation. At small angles with respect to the magnetic field (at angles of order ..mu../sub 0/=..sqrt..D/sub i perpendicular//D/sub e parallel/, where D/sub e, i parallel ,perpendicular/ are the electron and ion diffusion coefficients along and across the magnetic field) there are regions of width approx...mu../sub 0/ in which the Green's function changes sign, i.e., an increase in the plasma density at the origin of coordinates leads to loss of plasma from these regions. Under these conditions the spreading of a plasma inhomogeneity is governed, not by the smallest, but by the largest values of the diffusion coefficients along and across the magnetic field (D/sub e parallel/ and D/sub i perpendicular/). This situation turns out to be possible because of current flow through the plasma; this effect is analogous to Simon's familiar ''short-circuiting effect''. In this case the plasma itself fills the role of the conducting walls. Solutions are found for the cases of a point inhomogeneity and for an inhomogeneity of finite dimensions, an ellipsoid of revolution. There is an analysis of the conditions under which the plasma diffusion is ambipolar, i.e., under which the electron and ion fluxes are equal and there are no eddy currents. (AIP)
- Research Organization:
- M. I. Kalinin Leningrad Polytechnical Institute
- OSTI ID:
- 7312883
- Journal Information:
- Sov. J. Plasma Phys. (Engl. Transl.); (United States), Vol. 1:6
- Country of Publication:
- United States
- Language:
- English
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