Study of electron thermal transport on EAST superconducting tokamak

摘要

Improved electron confinement plasma produced by lower hybrid current drive (LHCD) has been obtained on the EAST superconducting tokamak, where the plasma current is sustained with the lower hybrid wave. The energy confinement time increases from 22.6 ms (Ohmic phase) to 33.2 ms (LHCD phase). The confinement factor H89 increases from 0.79 (Ohmic phase) to 1.3 (LHCD phase). The electron parameters profiles evolution and electron thermal transport coefficients are assessed primarily by using the data of Thomson scattering diagnostic and FIR laser interferometer. Electron heat diffusivity coefficient X_e profile was estimated during both the ohmically-heated plasma and the LHCD plasma by analyzing the electron power balance. The thermal diffusivity of electron became obviously lower in the LHCD phase. The relationship between X_e and the energy confinement time TE was studied in this paper. The role of the weak magnetic shear is invoked to partly explain the improved confinement by stabilizing the turbulence.This work was partially supported by the JSPS-CAS Core-University program in the field of 'Plasma and Nuclear Fusion'.