Electronic-polarization investigations of the electron velocity distribution function in an anisotropic plasma

The electron velocity distribution function (EVDF) in an anisotropic plasma is investigated using both the probe method and the magnetic-polarization Hanle techniques. In a helium beam-plasma discharge, the moments of the anisotropic EVDF are measured and the rate constant is determined for the disalignment of helium atoms in the 4¹ D ₂ state due to collisions with charged particles. A new method for investigating anisotropic properties of distant plasma objects unavailable for contact diagnostics is tested experimentally. The EVDF, the cross sections for the alignment of the total angular moments of the excited helium atoms by electron impact, and the degree of the electron pressure anisotropy are measured. An advantage of the method proposed is the possibility of directly measuring the EVDF anisotropy in distant plasma objects, which until now has been estimated only theoretically.