Application of He I Line Intensity Ratio Method to Lyot-Filter-Based Imaging Spectrometry on MAP-II Divertor Simulator

抄録

A simple, yet advanced technique of imaging spectrometry of divertor-relevant low-temperature plasmas using a wavelength-tunable Lyot filter spectral camera is herein proposed. The influence of the radiation-trapping effect in the atomic helium line intensity ratio method, characterized by the trapping radius, L_q, can be reduced using only the triplet series: 471(4³S)-, 587(3³D)-, and 706(3³S)-nm lines that are included in the tunable range of the above-mentioned Lyot filter. Approximate values of L_q can be estimated by adding 501(3¹P)- and 667(3¹D)-nm singlet lines, which enables stand-alone parameter imaging considering the radiation trapping.