Assessment of the strength of kinetic effects of parallel electron transport in the SOL and divertor of JET high radiative H-mode plasmas using EDGE2D-EIRENE and KIPP codes
Mar 7, 2018
15:30 - 16:30
KInetic code for Plasma Periphery (KIPP) was used to assess the importance of kinetic effects of parallel electron transport in the SOL and divertor of JET high radiative H-mode inter-ELM plasma conditions with the ITER-like wall and strong nitrogen (N2) injection. Plasma parameter profiles along B from one of the EDGE2D-EIRENE simulation cases were used as an input for KIPP, which in turn calculated electron distribution functions, fe, parallel power fluxes, electron-ion thermoforces, Debye sheath potential drops and electron sheath transmission factors at divertor targets. For heat fluxes in the main SOL, KIPP results showed deviations from classical (e.g. Braginskii) fluxes by factors typically ~ 1.5, with the flux limiting upstream and flux enhancement near entrances to the divertor. Inside the divertor, closer to the separatrix, very large heat flux enhancement factors, up to 10 or even higher, indicative of a strong non-local heat transport, were found at the outer target, with fe exhibiting bump-on-tail features at high energies. Under such extreme conditions, however, contributions of conductive fluxes to total power fluxes were strongly reduced, with convective fluxes becoming comparable, or even exceeding, the conductive fluxes. Electron-ion thermoforce, on the other hand, which is known to be determined mostly by thermal and sub-thermal electrons, was found to be in a good agreement with Braginskii formulas, including the Zeff dependence. Overall, KIPP results indicate, at least for plasma conditions used in this modelling, a sizable, but not dominant effect of kinetics on parallel electron transport.