Influence of recycling on the density limit in TEXTOR-94

An experimental investigation into density limits has been performed in the TEXTOR-94 limiter tokamak. In discharges close to the Greenwald limit, generally, a high-radiation-zone (Multifaceted Asymmetric Radiation from the Edge, or MARFE) precursor developed at the high-field side of the tokamak, which led to the destabilization of the plasma. In this Letter it is shown that recycling properties contribute to the development of the MARFE and hence the density limiting process. Reduction of the recycling yielded an increase of the achievable density of a factor of 2 above the Greenwald limit. Stationary discharges, operated at densities of 1.6x the Greenwald limit, have been obtained.