Characterization of heated dust particles using infrared and dynamic images in LHD

To investigate the dust properties, their movements were observed by a high-speed (time resolution of 5.3 ms) infrared camera in the Large Helical Device (LHD). Heated dust velocities were estimated to be 1 – 15 m/s in this experiment. We propose a method for revealing the three-dimensional position of heated dust particles using real and reflected images on the wall observed by an infrared camera. A simple theoretical model shows that the sizes of dust particles have been estimated using experimental observations, such as change of dust velocity and the background plasma parameters.