Electron Temperature Distribution Measurements in Clouds of Polystyrene Pellets Ablating in LHD Heliotron Plasma

• Published in: Technical physics letters 2018-05, Vol.44 (5), p.384-387
• Main Authors: Sharov, I. A., Sergeev, V. Yu, Miroshnikov, I. V., Kuteev, B. V., Tamura, N., Sudo, S.
• Format: Article
• Language: English
• Subjects: Classical and Continuum Physics; Clouds; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electron energy; ELECTRON TEMPERATURE; ELECTRONS; EMISSION; HELIOTRON; LHD DEVICE; Local thermodynamic equilibrium; LTE; MAGNETIC FIELDS; Measurement methods; PELLETS; Physics; Physics and Astronomy; PLASMA; POLYSTYRENE; Polystyrene resins; SPATIAL DISTRIBUTION; TEMPERATURE DISTRIBUTION; THERMODYNAMICS; WAVELENGTHS
• ISSN: 1063-7850; 1090-6533
• DOI: 10.1134/S1063785018050127

Two methods for measuring the spatial distribution of the temperature of electrons in a cloud near a polystyrene pellet that ablates in LHD heliotron plasma are described. The first method is based on measuring the ratio of the local emission-coefficient values at wavelengths of 486 ± 5 nm (the H β line) and 630 ± 5 nm (continuum). The second (new) method is based on the measurement of radiation distributions of the H β line in the direction along the magnetic field. Both the methods use an assumption about the partial local thermodynamic equilibrium in the cloud and show close results. It is shown for the first time that the temperature of cloud electrons increases from 0.8 eV in the immediate vicinity of the pellet surface to 6.0–7.0 eV at a distance of 6–8 mm from the pellet in the direction along the magnetic field, which agrees with the experimentally observed longitudinal distribution of the H β radiation in the cloud.