Experimental and numerical investigation of ion temperature in an ECR plasma

The ion temperature in a large diameter plasma is measured with the high-resolution optical emission spectroscopy. It is found that the ion temperature is low when the radial distribution of the plasma is flat profile compared with that in the case of peaked profile. The results of numerical calculation carried out by using the hybrid model validate the assumption of Boltzmann distribution in plasma and agree well with the experimental results. Thus, it is concluded that the decrease of the ion temperature is caused by the decrease of the radial electric field.