The effects of partition function cutoff on spectral temperature measurement in argon plasma

In order to evaluate the effect of cutoff criteria on spectral temperature measurement, partition functions are calculated for argon plasma at 3000–30 000 K using three different cutoff criteria (semi-empirical method, NIST data, and Griem’s theory). The effects of cutoff criteria on particle number density and plasma temperature measurements were discussed. The results indicate that as the plasma temperature increases, the degree of particle ionization increases and the cutoff effect weakens. The cutoff criteria have little impact on the calculation of the number density of the main components of the plasma but have a significant impact on the calculation of the number density of non-major components. The cutoff criterion using the NIST data can be reliably used for the temperature measurement, especially when the standard temperature method is used. Nevertheless, Griem’s theory should be considered for accurate calculation of radiation intensity.