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Sub-microsecond temporal evolution of edge density during edge localized modes in KSTAR tokamak plasmas inferred from ion cyclotron emission
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Chapman, Benjamin, Dendy, R. O., McClements, Kenneth G., Chapman, Sandra C., Yun, Gunsu S, Thatipamula, Shekar Goud and Kim, Minho (2017) Sub-microsecond temporal evolution of edge density during edge localized modes in KSTAR tokamak plasmas inferred from ion cyclotron emission. Nuclear Fusion, 57 (12). 124004. doi:10.1088/1741-4326/aa8e09 ISSN 0029-5515.
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Official URL: http://dx.doi.org/10.1088/1741-4326/aa8e09
Abstract
During edge localised mode (ELM) crashes in KSTAR deuterium plasmas, bursts of spectrally structured ion cyclotron emission (ICE) are detected. Usually the ICE spectrum chirps downwards during an ELM crash, on sub-microsecond timescales. For KSTAR ICE where the separation of spectral peak frequencies is close to the proton cyclotron frequency Ω<sub>cp</sub> at the outer plasma edge, we show that the driving population of energetic ions is likely to be a subset of the 3MeV fusion protons, born centrally on deeply passing orbits which drift from the core to the edge plasma. We report first principles modelling of this scenario using a particle-in-cell code, which evolves the full orbit dynamics of large numbers of energetic protons, thermal deuterons, and electrons self-consistently with the electric and magnetic fields. The Fourier transform of the excited fields in the nonlinear saturated regime of the simulations is the theoretical counterpart to the measured ICE spectra. Multiple simulation runs for different, adjacent, values of the plasma density under KSTAR edge conditions enable us to infer the theoretical dependence of ICE spectral structure on the local electron number density. By matching this density dependence to the observed time-dependence of chirping ICE spectra in KSTAR, we obtain sub-microsecond time resolution of the evolving local electron number density during the ELM crash.
| Item Type: | Journal Article | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Subjects: | Q Science > QC Physics | ||||||||
| Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||
| Library of Congress Subject Headings (LCSH): | Deuterium, Cyclotrons, Tokamaks | ||||||||
| Journal or Publication Title: | Nuclear Fusion | ||||||||
| Publisher: | Institute of Physics Publishing Ltd. | ||||||||
| ISSN: | 0029-5515 | ||||||||
| Official Date: | 25 October 2017 | ||||||||
| Dates: |
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| Volume: | 57 | ||||||||
| Number: | 12 | ||||||||
| Article Number: | 124004 | ||||||||
| DOI: | 10.1088/1741-4326/aa8e09 | ||||||||
| Status: | Peer Reviewed | ||||||||
| Publication Status: | Published | ||||||||
| Access rights to Published version: | Open Access (Creative Commons) | ||||||||
| Date of first compliant deposit: | 22 September 2017 | ||||||||
| Date of first compliant Open Access: | 27 September 2017 | ||||||||
| Funder: | Engineering and Physical Sciences Research Council (EPSRC), Research Councils UK (RCUK), Euratom, Han'guk Haksul Chinhŭng Chaedan [Korea Research Foundation] (HHCC), Fulbright Scholarship, Lloyd's (Firm). Scholarship, United States. Air Force. Office of Scientific Research (AFOSR), European Commission (EC) | ||||||||
| Grant number: | EP/G054950/1, EP/G056803/1, EP/G055165/1 and EP/M022463/1 (EPSRC), EP/P012450/1 (RCUK), 2014M1A7A1A03029881 (HHCC) |
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