Experiments to measure the relative confinement capability of a conventional aspect ratio tokamak versus a spherical tokamak were proposed by E. Synakowski as a joint DIII-D - NSTX venture at the recent brainstorming session. DIII-D and NSTX differ by a factor-of -2 in aspect ratio but have very similar poloidal size and shape. Several questions arise: Should this comparison be done at constant current or at constant toroidal field? What value should be adapted for the toroidal field in NSTX where it varies by a factor of -9 across the plasma? A memo was distributed (F. Perkins) that argues comparisons should be made at constant toroidal field at the magnetic axis because this determines the on-axis current density which is the maximum current density for inductively-driven discharges. In addition, q* - the ratio of average to maximum current density – should be constant which amounts to constant poloidal flux. q* is a measure of the shape of the relative current density profile. This means a factor-of-2 more current for NSTX than DIII-D. Additional constraints arise if the studies are to be carried out at constant β_p and ν*.

Initial analysis of a DIII-D discharge with ECCD indicates that by using a local basis function, EFIT can resolve the very peaked and localized ECCD profile. The reconstructed ECCD profile from a time series of EFIT analysis using MSE data agrees well with that predicted using the quasi-linear Fokker Planck code CQL3D.

Initial analysis of a DIII-D discharge with ECCD indicates that by using a local basis function, EFIT can resolve the very peaked and localized ECCD profile. The reconstructed ECCD profile from a time series of EFIT analysis using MSE data agrees well with that predicted using the quasi-linear Fokker Planck code CQL3D.