Spectroscopic Measurements of Impurities in the Upgraded DIVA Tokamak Plasma

Detailed spectroscopic studies of impurities have been made on the hydrogen plasma in the wavelength region from 10 to 1300 A with the upgraded DIVA tokamak device with a divertor. The toroidal field is 20 kG and the peak plasma current is 40 kA. Oxygen is the dominant impurity with the density of about 2% of the electron density. The effective ionic charge estimated from the amount of low-Z impurities (oxygen and carbon) is 2.4 to 3 in agreement with the value derived from the plasma conductivity. The emission spectrum of many lines observed in the region from 42 to 200 A is due to gold as impurity. Its spatial distribution has a peaked profile at a shorter wavelength and a hollow profile at a longer wavelength. The radiation power losses due to low-Z impurities and gold are estimated to be 30–35 kW and 27 kW, respectively, and the total power loss corresponds to 41–44% of the Joule-input power.