Measurement of polarization in Lyman-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"><mml:mi>α</mml:mi></mml:math> line caused by anisotropic electron collisions in LHD plasma

Polarization in the Lyman-α line caused by anisotropic electron collisions has been investigated Large Helical Device (LHD). High-sensitivity polarization-resolved measurements of from edge LHD plasma have carried out. To obtain spectra linearly polarized light at all angles a high-reflectivity mirror, polarization analyzer, and half-waveplate additionally installed into an existing VUV spectrometer system. These optical components designed developed CLASP (Chromospheric Lyman-Alpha Spectro-Polarimeter) [R Kano et al. ApJL, 839(1):L10, 2017] team. The present measurement made during cyclotron heated discharge. Intensity integrated over profile obtained plotted as function time to generate temporal line. shows that intensity varies synchronization with angle observed light, which clearly indicates is polarized. By performing least-squares fitting on profile, magnitude degree evaluated be 0.033 ± 0.004. In addition, phase analysis measured variation From this it found can attributed velocity distribution (EVDF) inboard side plasma. preliminary results simulation model code suggest value negative temperature perpendicular direction magnetic field higher compared parallel direction. Therefore, final −0.033±0.004.