Confinement in Advanced Inductive Plasmas - Gyroradius and Rotation

Advanced inductive (AI) plasmas promise long pulse operation and high fusion yield. We address issues of extrapolation to ITER and beyond. First, joint JET \& DIII-D work studies the scaling of transport with size ($\rho^*$). Preliminary 0-D analysis indicates that global scaling is close to Bohm-like: $B\tau_E\propto\rho^{*-\alpha}$ with $\alpha\approx 2.16$. For matched discharges $H_{98y2}$ depends weakly if at all on $\rho^*$. Second, the dependence of confinement on rotation and on the presence of an NTM island was studied in DIII-D. Rotation was varied by a factor of $\sim$4.6 in plasmas with similar $n_e$ and $\beta$, with $3.1\leq q_{95}\leq 4.9$. $H_{89}$ increased from $\sim$2.0 to $\sim$2.5, with weak $q_{95}$ dependence. Increasing $E\times B$ flow shear is dominant, accompanied by a decrease in turbulence. Decreasing NTM island width is less important, but not negligible. Third, with added ECH, $T_e/T_i$ increases but energy and momentum transport increase as well. Matching NBI and ECH heated plasmas shows that the reduction in density with ECH is a consequence of reduced rotation rather than changing $T_e/T_i$.