- Conference date: 5-8 October 2004
- Location: Toki (Japan)
Plasma Polarization Spectroscopy (PPS) has been applied to a helium plasma produced by ECR heating in a cusp‐configuration magnetic field. Several neutral helium lines are found linearly polarized. The directions of polarization are perpendicular to the magnetic fields, and the polarization degrees are from several to more than ten percent. From the observed intensity and polarization degree, we deduce the population and alignment of the upper levels of these lines. The Population‐Alignment Collisional‐Radiative model is constructed, and the observed results are interpreted in terms of an anisotropic velocity distribution of electrons. The distribution is found to be of a Saturn‐type with, for example, the central component with temperature 14 eV and the ring component of 40% electrons displaced by 9.2 eV having the same temperature. Differences in the calculated populations and alignments for different cross section data are discussed.
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