Conceptual design of Thomson scattering system for detecting electron temperature anisotropy in magnetically confined plasma.
Hoshi Kodai K, Funaba Hisamichi H, Sakai Kentaro K, Uehara Hiyori H et al.
In magnetically confined plasmas, electron temperature anisotropy can be formed as a difference between the electron temperatures parallel and perpendicular to the magnetic field. In Compact Helical Device (CHD), a high temporal resolution Thomson scattering system is planned to be installed, which may enable detailed measurements of the temporal evolution of anisotropy. In this study, we designed Thomson scattering system configurations for detecting electron temperature anisotropy in CHD and evaluated the feasibility of anisotropy detection. We found that the single-pass configuration using an additional observation system can detect a temperature difference of 1.4 times between the perpendicular and parallel directions in the core region, although its detection performance deteriorates in the peripheral region. In contrast, the double-pass configuration using an additional counter-propagating laser path can detect a difference of 1.3 times over a wide radial range. These results indicate that the proposed configurations provide a basis for time-resolved measurements of electron temperature anisotropy in CHD.