Electron thermal conductivity in the trapped electron regime in the FM-1 spherator

The parametric dependence of electron thermal conductivity was studied in the trapped electron regime by utilizing a localized heating method in a shear stabilizing configuration in the FM-1 spherator. The electron thermal conductivity K⊥ and the particle diffusion coefficient D⊥ show similar dependence on the shear length, Ls, and the electron temperature Te[K⊥ ∼ (1/400 ∼ 1/800)(Ls/a) (kTe/16eB)]. The conductivity was larger when the electron temperature gradient was parallel to the density gradient compared with the antiparallel case. The fluctuations associated with the heat flow are compared with the prediction of the trapped electron particle instability. Relevance to tokamak experiments is discussed.