Year: 1990
Type: article
Abstract: Impurity concentration profiles have been determined for H-mode discharges in the DIII-D tokamak from measured n e , T e , Z eff and radiated emissivity profiles. The central impurity levels in DIII-D high current H-modes, as modelled using this technique, remain below those seen in L-modes (fractional nickel concentrations ≤0.02%) throughout the neutral beam heating pulse. In contrast to some other experiments (ASDEX [1], JET [2], JFT-2M [3]), the H-mode does not terminate because of excessive radiation in DIII-D discharges heated with co-injected neutral beams. For increasing plasma current, the global impurity concentrations decrease and the profiles become more dominated by edge radiation. H-modes as obtained with electron cyclotron heating and co-injected neutral beams at similar heating powers also have low impurity levels, but the impurity distribution is significantly more hollow in the case of neutral beam heating.
Source: Nuclear Fusion
Authors: D.A. Content, H.W. Moos, M.E. Perry, N.H. Brooks, M. Ali Mahdavi, T.W. Petrie, H. St. John, D.P. Schissel, R.A. Hulse
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: U.S. Department of Energy
OpenAlex ID: W2060740994