The deduction of low-Z ion temperature and densities in the JET tokamak using charge exchange recombination spectroscopy
Charge exchange recombination spectroscopy (CXRS) has been used on JET to study fully stripped low-Z species. The ion temperature in the plasma centre was measured from visible lines of helium, carbon and oxygen excited by charge exchange with heating neutral beam particles. A cold component produced at the plasma edge was apparent on helium and carbon spectra. The charge exchange feature was unambiguously isolated for the various composite lines and all three impurities agreed on the same temperature within the experimental error. Toroidal rotation velocity measurements were made near r/a of about 0.65 on the high field side. Observed column emissivities were converted into absolute impurity densities using a neutral beam attenuation code and newly calculated charge exchange effective rate coefficients. The models took detailed account of cascading and the influence of the plasma environment in causing l-mixing, and allowed the n-dependence of the rate coefficients to be addressed experimentally using some carbon transitions. The effective ion charge reconstructed from simultaneous measurements of the densities of dominant impurities shows good agreement with the value inferred from visible bremsstrahlung. Significant differences in the ratio of helium, carbon and oxygen impurities were observed.
Bibliographic Reference: Report: JET-P(87)44 EN (1987)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 198910257 / Last updated on: 1994-12-01
Original language: en
Available languages: en