Transport simulation of advanced tokamak operations

Plasma confinement and performance for advanced tokamaks are likely to be limited by magnetohydrodynamic stability. Transport simulation studies are carried out to evaluate the effectiveness of current profile control in raising the stability limits thereby allowing for high confinement and high beta operations in steady-state. The authors focus on advanced tokamak regimes with experimentally-demonstrated confinement improvements in the plasma core, such as high plasma internal inductance ell i, and negative central magnetic shear. Key issues to be addressed include the relationship between current profile and pressure profile, coupled through the bootstrap current, in order to improve plasma stability, and the optimum ratio of bootstrap current and rf-driven current to minimize rf power requirement and maximize performance