CONVOLUTION-FITTING METHOD FOR DOPPLER-BROADENING PLASMA ION TEMPERATURE-MEASUREMENT

To estimate the ion temperature of plasma using Doppler broadening with a low-resolution monochromator, a convolution-fitting method was proposed. This method utilizes the information of the slit function of the monochromator to improve the effective resolution. It consists of a convolution calculation of trial functions and the slit function, and a fitting of the result with a measured line spectrum. A model experiment was carried out to demonstrate the usefulness of the method. The measured lines were C III 2296.8 Angstrom and C V 2270.9 Angstrom, from JIPP T-IIU Tokamak. The slit function was obtained by measuring Hg I 2656.5 Angstrom, line from a mercury lamp. Applying the method to these lines, effective resolution was improved by a factor of about seven.