Study of ion-gyroscale fluctuations in low-density L-mode plasmas heated by NBI on KSTAR
SCIE
SCOPUS
- Title
- Study of ion-gyroscale fluctuations in low-density L-mode plasmas heated by NBI on KSTAR
- Authors
- Lee, Woochang; Ko, SH; LEEM, JUNEEOK; YUN, GUNSU; Park, HK; Wang, WX; Budny, RV; Kim, KW; Luhmann Jr., NC
- Date Issued
- 2018-02
- Publisher
- INT ATOMIC ENERGY AGENCY
- Abstract
- Broadband density fluctuations with peak frequency ranging from 150 to 400 kHz were measured using a multichannel microwave imaging reflectometer in core region of the low-density L-mode plasmas heated by neutral beam injection on KSTAR. These fluctuations have been studied by comparing the dominant mode scales estimated from the measurement with those predicted from linear gyrokinetic simulation. The measured poloidal wavenumbers are qualitatively comparable to those of the 'fastest growing modes' from simulations, whereas they are larger than those of the 'transport-dominant modes' by about a factor of three. The agreement on wavenumbers between the measurement and linear simulation (for the fastest growing modes) is probably due to sufficiently weak $E \times B$ flow shear compared to the maximum linear growth rate. Meanwhile, the transport-dominant modes seem to be related to the fluctuations in lower frequencies (~80–150 kHz) observed in some of the measurement.
- Keywords
- Imaging systems; Particle beam injection; Reflectometers; Shear flow; Density fluctuation; Dominant mode; Gyrokinetic simulations; Gyroscale; Linear growth rate; Linear simulation; Microwave imaging reflectometers; Neutral beam injection; Plasma simulation
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/41343
- DOI
- 10.1088/1741-4326/aaac4b
- ISSN
- 0029-5515
- Article Type
- Article
- Citation
- NUCLEAR FUSION, vol. 58, no. 4, page. 046009, 2018-02
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