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Title: Resolving interactions between ion-cyclotron range of frequencies heating and the scrape-off layer plasma in EAST using divertor probes

Journal Article · · Plasma Physics and Controlled Fusion

Waves in the ion-cyclotron range of frequencies (ICRF) used for tokamak heating are known to interact strongly with the scrape-off layer (SOL) plasma, potentially limiting ICRF performance. We present the effect of ICRF heating on triple-probe signals in the Experimental Advanced Superconducting Tokamak (EAST) experiment, an advanced superconducting tokamak with two ICRF antennas and 12 MW of ICRF source power in support of high-power and long-pulse operation. Applying time-resolved magnetic mapping to the divertor probe arrays enables detailed sensing of the spatial structure of the SOL modifications. We observe a sharp transition in floating potential from negative to positive over a length scale of a centimeter at a major radius just inboard of the ICRF antenna. The largest changes in floating potential are observed not for probes connecting to the active ICRF antennas but rather to the main limiter or limiters for inactive lower hybrid launchers. Ion saturation current can be greatly reduced for probes mapping just in front of an antenna. Where relevant, comparison with results from the National Spherical Torus Experiment are made. This work will provide insight into sputtering, impurity production and antenna coupling as higher ICRF power levels are attempted on EAST.

Research Organization:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Sponsoring Organization:
USDOE
Contributing Organization:
This research is supported by supported partly by the National Key Research and Development Program No. 2016YFA0400601 and also by the China Magnetic Con finement Fusion Science Program No. 2015GB101001
Grant/Contract Number:
AC02-09CH11466
OSTI ID:
1558765
Journal Information:
Plasma Physics and Controlled Fusion, Vol. 61, Issue 4; ISSN 0741-3335
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 17 works
Citation information provided by
Web of Science

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