Distant diagnostics of nonequilibrium plasmas

Abstract

Developing plasma diagnostics methods are vital for various kind of plasma applications1. This talk discusses the method for direct remote measurements of electron velocity distribution function (EVDF) in plasma by combination of the flat one-sided probe technique2,3 and magnetic polarization Hanley method. Under laboratory conditions, model plasma object is created, that contains atoms of the same chemical element as in remote plasma. The EVDF Legendre components f 0 and f 2 and the degrees of polarization of two lines of spontaneous emission are measured simultaneously. If f 0 and f 2 are known and the degree of polarization of the R-th and T-th spectral lines is P ≈ ρ 2 /ρ 0 , then, for model plasma object with a certain atomic composition we can calculate the alignment (Q 2 ) and excitation (Q 0 ) cross sections using following system of equations: equation It should be noted, that Q 2 and Q 0 are invariant for model plasma object and remote plasma with the identical atomic composition. In order to analyze the EVDF in remote plasma it is necessary to measure the degrees of polarization PR and P T of spontaneous emission and, using the invariant atomic constants Q 0 and Q 2 , find the isotropic (f 0 ) and anisotropic (f 2 ) components of the EVDF from eq. (1).