JET-P(89)12

Local Transport in Sawtooth-Free JET Discharge

Application of ICRH to the central region of the plasma can produce sawtooth free periods of duration several confinement times andcentral electron temperatures in excess of l0keV. The resulting electron transport is studied locally by examining the relationship between total heat flux and temperature and density gradients. The spatial profile of heat diffusivity is found to be virtually independent of plasma current in the central region and strongly dependent upon current in the outer region. When this result is combined with those obtained from respectively RF modulation experiments, heat pulse propagation measurements and transient plasma responses from pellet injection, a coherent picture of heat diffusivity profiles emerges: Together these results confirm that the global confinement time has a dependence upon plasma current which is weaker than linear.
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JETP89012 706.97 Kb