Spectroscopic investigations of tungsten in the EUV region and the determination of its concentration in tokamaks
By means of laser ablation, tungsten was injected in both the ohmic and additionally heated plasmas of the ASDEX Upgrade tokamak experiment. Spectroscopic investigations were performed in the extreme ultraviolet (EUV) wavelength region between 4 nm and 140 nm. Beside the quasicontinuum structure at 5 nm, isolated lines of tungsten were observed in the regions between 4.5 nm and 6 nm and between 12 nm and 14 nm. By comparison with calculations from the HULLAC and RELAC codes, these lines could be identified as transitions of Br-like to Ni-like tungsten ions. The concentration c(W) of tungsten after laser ablation was determined from comparisons between the total tungsten radiation P(W) and calculated radiation losses. Calibration of the quasicontinuum intensity with the help of the P(W) measurements allowed the determination of the tungsten concentration from spectroscopic observations, which are more sensitive. Both concentration measurements (quasicontinuum, P(W)) agree well in discharges with laser ablation. From a comparison of the intensity of the isolated lines with code results, c(W) could be estimated in the central region of hot, additionally heated plasmas. The lower detection limit of the spectroscopic method allows the extraction of c(W) during the tungsten divertor experiment of ASDEX Upgrade.
Bibliographic Reference: Report: IPP 10/9 EN (1997) 27pp.
Availability: Available from the Max-Planck-Institut für Plasmaphysik, 85748 Garching bei München (DE)
Record Number: 199810245 / Last updated on: 1998-03-09
Original language: en
Available languages: en