Quantitative measurement of in-vessel dust velocity and its correlation with toroidal rotation of plasmas

Abstract

In-vessel dust velocity and its distribution have been evaluated by using dedicated software developed at KSTAR. The dust velocities are well described by log-normal distribution function in a range from ∼10m/s up to ∼460m/s. The peak velocity of the distribution increases through three campaigns from 2010 to 2012, mainly due to the increase of the input energy level. From the force balance, it is expected that the dust velocity is strongly correlated with the toroidal plasma flow due to the ion drag force acting on dusts. To confirm this, toroidal rotation velocity is measured by using charge exchange spectroscopy (CES) as a function of normalized stored energy (W/Ip), which is similar with Rice scaling. As a consequence, it is found that the dust velocity is linearly proportional to W/Ip, thus to the toroidal rotation velocity of the plasmas.