Varying the pre-discharge lithium wall coatings to alter the characteristics of the ELM-free H-mode pedestal in NSTX

[摘要] A previous experiment in the National Spherical Torus Experiment (NSTX) showed that pre-discharge lithium deposition gradually suppressed edge-localized modes (ELMs) and had nearly continuous relationships with reduced recycling and transport. In this paper, additional data filled gaps in the earlier experiment, and demonstrates that recycling, confinement, and pedestal structure continued to improve with additional lithium, even after ELMs were completely suppressed. New analysis shows that toroidal rotation and ion temperature also increased continuously with additional lithium. Besides its evolution with additional lithium, we also characterize the time evolution of the ELM-free H-mode pedestal as average density rose and impurities accumulated. We find that the pedestal structure, divertor heat flux and Da profiles, and inferred recycling coefficient did not change significantly, at least until radiative losses become dominant. This suggests that the low-recycling properties of lithium were not significantly degraded over the duration of the discharge. (C) 2013 Elsevier B. V. All rights reserved.

[发布日期] 2013-07-01

[效力级别]  Proceedings Paper