Wave Absorption Profile during ICRF Heating in Mixed Plasma in Large Helical Device

Abstract

A minority ion ratio in fast wave heating for the ion cyclotron range of frequencies affects plasma heating mechanisms and mode conversion ratios to short waves in a mixed plasma. The mode conversion region and these wave absorption profiles are functions of minority ion ratio, and direct wave absorption by electrons increases when the minority ion ratio exceeds about 6% in a simple two-dimensional wave absorption calculation with a single toroidal mode. At the minority ion ratio of 10%, the amount of absorption by electrons is comparable to that by ions. We find a significant relationship between the minority ion ratio and the wave absorption profile, exceeding the minority ion ratio of 10% for wave absorption to electrons.