Local Energy and Particle Transport in Burst-Free H-Phases of ASDEX

摘要

Flux-surface-averaged transport in high-confinement (H) discharges with burst-free phases is analyzed by computer modelling. The electron heat diffusivity CHI/sub e/ and diffusion coefficient D in undisturbed H phases are found to be about twice as small as those in ordinary H discharges with high-frequency bursts. Scaling relations for CHI/sub e/, D and v/sub in/ are successfully applied. The confinement properties of ohmically heated plasmas are not recovered in the H regime. Ion heat conduction continues to be neoclassical. The steep rise of the impurity radiation loss is explained by the increase in electron density and accumulation of the iron impurity. The dominant loss channels are electron heat conduction and impurity radiation. Conductive and convective energy losses due to the ions are negligibly small. (ERA citation 14:026048)