HIGHER FUSION POWER GAIN WITH CURRENT AND PRESSURE PROFILE CONTROL INSTRONGLY SHAPED DIII-D TOKAMAK PLASMAS

Fusion power has been increased by a factor of 3 in DIII-D by tailorin g the pressure profile to avoid the kink instability in H-mode plasmas . The resulting plasmas are found to have neoclassical ion confinement . This reduction in transport losses in beam-heated plasmas with negat ive central shear is correlated with a dramatic reduction in density f luctuations. Improved magnetohydrodynamic stability is achieved by con trolling the plasma pressure profile width. In deuterium plasmas the h ighest gain Q (the ratio of fusion power to input power), was 0.0015, corresponding to an equivalent Q of 0.32 in a deuterium-tritium plasma .