A Predictive Model for the Greenwald Density Limit

Authors:  Q. Teng, D.P. Brennan, L. Delgado-Aparicio, D.A. Gates, J. Swerdlow and R.B. White

Abstract:  The Greenwald density limit is reproduced for the first time using a phenomenologically correct model with experiment-relevant parameters. A simple model of equilibrium and local power balance inside the island during its evolution has been implemented to calculate the radiation-driven thermo-resistive tearing mode growth and explain the density limit. Strong destabilization of the tearing mode due to an imbalance of local Ohmic heating and radiative cooling in the island predicts the density limit within a few percent with reasonable assumptions for impurity densities.  Results are robust to a substantial variation in model parameters within the range of experiments.
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Submitted to:  Physical Review Letters
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Download PPPL-5191 (pdf 2 MB 14 pp)
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