Poloidal rotation in the limb of the TEXTOR plasma measured by the Doppler shift of a BII-line
Local measurements of the poloidal rotation of the plasma near the boundary layer of a tokamak attract considerable interest because the poloidal shear, produced by a differential rotation in the plasma boundary, can decorrelate radial turbulence. The analysis of this problem shows a bifurcation-like behaviour of the plasma boundary pointing to an impact of the boundary condition on the capability of energy confinement in the bulk of a tokamak plasma. TEXTOR is the largest experiment in which the influence of artificially introduced radial electric fields on a plasma heated by neutral beams and by ICRH is studied. More direct access to the rotation velocity is offered by the Doppler effect, which causes a wavelength shift of the spectral lines emitted by atoms and ions in the rotating layer. Spatial resolution, often a problem in spectroscopy, can be achieved by choosing a stage of ionisation existing in a thin layer only. Near the plasma boundary this is the case if the ionisation energy increases weakly for subsequent stages only. A BII line at 494.0 nm proved to be particularly suitable and the results are included in this paper.
Bibliographic Reference: Article: Proceedings of the 19th Conference on Controlled Fusion and Plasma Physics, Vol. 2 (1992) pp. 775-778
Record Number: 199211307 / Last updated on: 1994-11-29
Original language: en
Available languages: en