TRANSITION FROM TOROIDAL TO SLAB TEMPERATURE-GRADIENT DRIVEN MODES

In the local approximation the electrostatic dispersion relation for the (ion or electron) temperature gradient driven modes is solved retaining the full guiding-center resonance condition omega = k parallel-to upsilon-parallel-to + k.v(D) (upsilon-perpendicular-to 2, upsilon-parallel-to 2). Increase of the slab-to-toroidal ratio parameter k parallel-to upsilon-T/k perpendicular-to upsilon-D is shown to directly increase the threshold value of the temperature-to-density gradient parameter eta-c. Therefore, the local anomalous heat flux has a strong dependence on the safety factor q when k parallel-to approximately 1/qR.