ANALYSIS OF LOCAL HEAT FLUX IN JET
The total heat flux q arising in steady state from ohmic and neutral beam heating is calculated for a series of power scan experiments on JET. A radial resolution of q at selected radii is made to examine the dependence of q upon local plasma parameters such as density n-"rm e", temperature T-"rm e", current I and their gradients. Non-linear regression analysis techniques are applied to fit the data on q to empirical expressions q-"rm fit" involving the local plasma parameters. The most plausible fit emerging from the analysis is q_"rm fit"=-(C/I)n-"rm e"nablaT-"rm e" - q-"rm pinch in which C is a constant, I the current enclosed by a plasma surface and q_"rm pinch" a constant so- called heat pinch. The net heat diffusivity inferred from this relationship agrees with estimates from heat pulse propagation measurements and it leads to a scaling law for the incremental energy confinement time which agrees with the one determined experimentally. There is a substantial amount of scatter in the data due to approximations made in the analysis and due to uncertainties in the experimental measurements.
Bibliographic Reference: REPORT JET-P(87)48, 1987, AVAILABILITY: JET, ABINGDON, UK
Record Number: 1989126096000 / Last updated on: 1989-05-01
Available languages: en