Testing Pedestal Models for Joint Research Target on DIII-D

As part of the FY2011 DOE Joint Research Target on Pedestal Physics, tests are being performed on DIII-D for gyrokinetic modes that have been proposed as physics mechanisms for controlling the H-mode pedestal structure. These modes include kinetic ballooning modes (KBM), candidates for limiting the total pedestal pressure gradient, ion temperature gradient modes (ITGM), candidates for limiting the $T_i$ gradient at the pedestal top and electron temperature gradient modes (ETGM), candidates for limiting the $T_e$ gradient both in the pedestal and on top of the pedestal. The theoretical control parameters for these modes are $\alpha_{MHD}$ for KBM, $\eta_e$ for ETGM and $\eta_i$ for ITGM. Experiments are being performed in DIII-D to determine if measured values of these parameters are close to the theoretical threshold values for the linear onset of these modes.