Charge screening in a plasma with an external ionization sourceстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:An asymptotic theory for the screening of the electric field of a dust particle or a spherical probe in a plasma with an external steady and/or internal (proportional to the electron density) gas ionization source has been developed for the first time. It has been established that the screening of the charge of a spherical body adsorbing the charge of the incident plasma particles is described by a superposition of two exponentials with different screening constants. The two exponentials are retained even in the absence of nonequilibrium fluxes on the macroparticle and only in the special case of an isothermal plasma does the screening become Debye one. The screening length is determined by the ratio of the electron-ion, beta(ei), and Langevin, beta(L) = 4 pi e mu(i) (where mu(i) is the ion mobility), recombination coefficients. If beta(L) >> beta(ei), then it is much larger than the electron Debye length. The ions in an isothermal plasma have been found to give the same contribution to the screening as the electrons if the electron-ion recombination coefficient exceeds the Langevin ion recombination coefficient by a factor of 2 or more, beta(ei) >= 2 beta(L). The Vlasov equation is used to analyze the asymptotic behavior of the macroparticle potential in a collisionless plasma.