The m=1 Convection Cell and Sawteeth in Tokamaks

Resistive magnetohydrodynamic (MHD) simulations of sawtooth activity in tokamaks are presented. An m=1 convection cell driven by the resistivity gradient forms in the center of the column and causes the sawteeth to die away. The nonlinear properties of this convection cell are calculated analytically. Periodic sawteeth are obtained when the parallel thermal conduction is sufficiently large.