Probe Measurements of Electron Energy Distributions in a Magnetized Plasma of the Toroidal Device “BLAAMANN”

Abstract

The probe-current densities j and their first j' and second j derivatives with respect to the probe potentials in magnetized plasmas of the toroidal device “Blaamann” have been measured. For analysis of data a kinetic probe theory was used. The comparison of measured and calculated j and j' shows that electron energy distributions in the plasmas are close to Maxwellian and allows us to calculate electron temperatures and densities. Application of the Langmuir probe theory for unmagnetized plasmas for investigated conditions gives too high electron temperatures (up to 30–40%) and too low densities (with factor from 3 to 10). The measured and calculated j have more complicated structure (they may have additional maximums) than in the case of unmagnetized plasmas. The possibility of direct probe measurements of ion energy distributions in the magnetized plasma is discussed.