ROLE OF EDGE ELECTRIC-FIELD AND POLOIDAL ROTATION IN THE L-H TRANSITION

Marked changes in the edge radial electric field Er and in the edge poloidal rotation velocity v are important signatures of the L-H transition in the DIII-D tokamak. Shear exists in Er and v and increases from the L mode to the H mode. A comparison of experiment with theory shows that shear in Er and v is sufficient to suppress edge fluctuations, that ion-orbit loss is large enough to be the source of v, and that Er and v may play a causal role in the L-H transition. © 1990 The American Physical Society.