Laser-induced fluorescence at Lyman-α in the plasma edge of TEXTOR-94

A new pulsed laser system for laser-induced fluorescence (LEF) measurements on deuterium in front of a graphite test limiter in the plasma edge has been installed on TEXTOR-94. The spectral resolution of the system is about 0.5 pm in the VUV without fine intracavity etalon, which is 0.2 pm better than the resolution of the previous system with etalon. Measurements of the line profile of atomic deuterium L-alpha were performed at pulse frequencies of 25 Hz both in the laboratory and in TEXTOR-94. In TEXTOR, velocity distributions of the recycled atoms have been recorded for different radial and poloidal positions. The existence of a large contribution of "slow" atoms with kinetic energies below 1 eV in radial direction (covered range: 0-16 eV) was confirmed [1]. One explanation for the origin of these atoms is their production by dissociation of molecules or of molecular ions from vibrationally excited states [2, 3].