Wideband high-resolution spectroscopy on Al-pellet ablation plasmas in large helical device

An aluminum pellet has been injected into a high-temperature plasma produced in the Large Helical Device (LHD). Emission from an ablation cloud of the pellet in a whole visible range is simultaneously measured with an echelle spectrometer having an instrumental resolution from 0.055 nm at 400 nm to 0.10 nm at 750 nm. More than 50 of Al I, II, III and IV lines are resolved. We estimate the electron temperature and density of the ablation cloud from the intensity distribution and Stark broadening of the emission lines, respectively. The electron temperature and density are found to show increase and decrease, respectively, as an increase in the charge state of aluminum. We also determine the Stark broadening coefficients of several Al II lines from the observed Stark widths.