Effect of edge turbulence on threshold of multifaceted asymmetric radiation from the edge instability in tokamaks

Abstract

The radiative condensation instability believed to be responsible for the occurrence of multifaceted asymmetric radiation from the edge (MARFE) in tokamaks has been investigated in the presence of a background turbulence of saturated drift resistive ballooning modes (DRBM). These modes are a natural source for edge fluctuations in tokamaks. For the m = 1 MARFE, it has been shown that a modest level of DRBM turbulence can significantly lower the threshold radiation rate required for excitation of MARFEs, enhance its growth rate, and introduce a real part to the mode frequency. Some of these results are consistent with observations of onset of MARFEs in recent experiments on Joint European Torus (JET) [Proceedings of the 17th European Conference on Controlled Fusion and Plasma Heating, Amsterdam (European Physical Society, Petit-Lancy, 1990), Vol. 14b-1, p. 339] and Tokamak Experiment for Technology Oriented Research (TEXTOR) [Phys. Rev. Lett. 71, 1549 (1993)].