Annual Progress Report Georgia Tech Fusion Research Center Assembled

The dependence of plasma rotation and heating power on the density limit for MARFE onset hasbeen studied on TEXTOR using different mixtures of auxiliary heating methods (ICRH, co-, andctrNBI). The edge density limit in the plasma heated by NBI is two times larger than thatobserved in the plasma heated by ICRH ( PNBI= PICRH= 1.3 MW). The dependence of the densitylimit with regard to NBI direction is not noticeable, which could be because variation of plasmaedge rotation by NBI is one or two orders of magnitude lower than the ion sound speed. Theexperimental data indicates that the different heating methods change the distribution of theneutral particle flux, which plays an important role in determining the threshold for the MARFEonset.