A mechanism for the sawtooth collapse

The periodic collapse of the plasma pressure inside of the inversion radius r$_{inv}$ results from the absence of a permanent adequate cross -field transport mechanism in this region. For example, trapped electron mode induced transport, which is believed to play a major role in the tokamak confining region r $\geq$ r$_{*}$ ~ r$_{inv}$, decreases rapidly at smaller radii. In the present work, a mechanism is proposed to explain how the sawtooth precursor - a transient macroscopic tearing mode - can trigger the sawtooth collapse. By deforming the original magnetic flux surfaces with q 2; this condition suggests a novel interpretation of the occurence of "monster" sawteeth