Application of laser-induced fluorescence to problems of plasma-wall interactions in tokamaks
An optical system has been installed in the sector of the limiter lock of TEXTOR in order to study by laser induced fluorescence the density and velocity distribution of atomic impurities and recycling hydrogen in front of a test limiter. First experiments were carried out on the sputtering of Si-atoms from a SiC-limiter; fluorescence of the Si I-line 251.6 nm (3P(2) - 3P(0,2)) was observed. A pulsed, frequency-doubled dye laser was used, with a repetition rate of 20 Hz. By means of fast pressure tuning of the laser wavelength during the flat-top of the plasma shot, spectral profiles were measured with a resolution of 1 pm, with an average line density around 2 x 1.0 E13/cm3. The profiles correspond to sputtered atoms escaping from the limiter. A comparison of these results with those of laboratory experiments has been performed, where a Si-wafer was sputtered by 1 keV He or Ne ions. A strong dependence of the sputtering yield on the oxygen partial pressure was found.
Bibliographic Reference: Article: 6th International Symposium on Laser-aided Plasma Diagnostics, Bar Harbor, Maine (US) : Proceedings (1993) pp. 1-6
Record Number: 199410043 / Last updated on: 1994-11-28
Original language: en
Available languages: en