Session CO3 - NSTX and Other ST.
ORAL session, Monday afternoon, November 15
Room 204/205, SCC
The National Spherical Torus Experiment (NSTX) has completed a program of experiments which spanned significant ranges for the dominant engineering variables in the scaling of energy confinement in conventional tokamaks. The experiments included well controlled scans in H-mode plasmas of the plasma current and neutral beam heating power. The energy confinement time has been determined by equilibrium analysis based on external magnetic measurements and confirmed for a subset of discharges by analysis of the kinetic measurements with the TRANSP code. The variation in the global energy confinement time with current and heating power matches quite closely the dependences in the ITER-98pb(y,2) H-mode scaling both in the single-parameter scans and regression to the overall database. Nevertheless, for neutral beam heated H-mode plasmas, the global confinement exceeds the H-mode scaling predictions by a factor up to 1.6. In L-mode plasmas the confinement often exceeds the H-mode scaling predictions as well. These trends and the results of the TRANSP analysis will be presented.