DRIFT-WAVE TEST PARTICLE-TRANSPORT IN REVERSED SHEAR PROFILE

Drift wave maps, area preserving maps that describe the motion of char ged particles in drift waves, are derived. The maps allow the integrat ion of particle orbits on the long time scale needed to describe trans port. Calculations using the drift wave maps show that dramatic improv ement in the particle confinement, in the presence of a given level an d spectrum of ExB turbulence, can occur for q(r) profiles with reverse d shear. A similar reduction in the transport, i.e., one that is indep endent of the turbulence, is observed in the presence of an equilibriu m radial electric field with shear. The transport reduction, caused by the combined effects of radial electric field shear and both monotoni c and reversed shear magnetic q profiles, is also investigated. (C) 19 98 American Institute of Physics. [S1070-664X(98)03711-2].