Deuterium high-confinement (H-mode) plasmas, lasting up to 3.45 s, have been generated in the EAST by ion cyclotron range of frequency (ICRF) heating. H-mode access was achieved by coating the molybdenum-tiled first wall with lithium to reduce the hydrogen recycling from the wall. H-mode plasmas with plasma currents between 0.4 and 0.6 MA and axial toroidal magnetic fields between 1.85 and 1.95 T were generated by 27 MHz ICRF heating of deuterium plasma with hydrogen minority. The ICRF input power required to access the H-mode was 1.6–1.8 MW. The line-averaged density was in the range (1.83–2.3) × 1019 m−3. 200–500 Hz type-III edge localized mode activity was observed during the H-mode phase. The H-mode confinement factor, H98IPB(y, 2), was ∼0.7.
The experiments were carried out to study the coupling characteristics of the I-port antenna in the ion cyclotron range of frequencies (ICRF) in EAST. The dependencies of the coupling resistance on various parameters including the antenna position, the central electron density, gas injection and the antenna phasing have been studied. The results obtained show that the experimental data are consistent with theoretical simulations. We find that the antenna loading resistance decreases sharply at the L-H transition due to the change of the plasma density profiles in the scrape-off layer (SOL). The effect of the low hybrid wave (LHW) on the ICRF coupling during the H-mode is observed. The theoretical interpretation of the results is discussed, together with the efficient methods to optimize the coupling efficiency.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.