General Physics Seminar Thursday 19 December 2002


Internal Transport Barriers in Tokamak Plasmas

R. C. Wolf

Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, Association EURATOM/FZJ, Trilateral Euregio Cluster, D-52425 Jülich, Germany



Internal transport barriers in tokamak plasmas are explored in order to improve confinement and stability beyond the reference scenario, used for the ITER(^) extrapolation, and to achieve higher bootstrap current fractions as an essential part of non-inductive current drive.

Internal transport barriers are produced by modifications of the current profile using external heating and current drive effects, often combined with partial freezing of the initial skin current profile. Thus, formerly inaccessible ion temperatures and QDTeq(#) values have been (transiently) achieved. The talk reviews the state of the art of these techniques and their effects on plasma transport in view of optimizing the confinement properties. Implications and limits for possible steady state operations and extrapolation to burning plasmas are discussed.



(^) : ITER stands for International Thermonuclear Experimental Reactor, the planned next step towards a commercial fusion reactor.

(#) : This figure of merit is the fusion power which would have been produced if the optimum Deuterium-Tritium mixture would have been used (in stead of the pure Deuterium plasma which is normally used).