THE SCALING OF THE GIANT ELM FREQUENCY

A dimensionally correct expression for the scaling of the giant edge l ocalized mode (ELM) frequency based on the magnetohydrodynamic (MHD) i nterchange instability is presented. Tokamak experiments reveal that E LM events can occur below (but close to) the ideal MHD threshold. The physical model is extended in two ways, namely to include geometrical effects and dissipative terms. It is shown that both effects can play an important role in the explanation of the ELM physics.