Ion gyroscale fluctuation measurement with microwave imaging reflectometer on KSTAR

W Lee; J Leem; G S Yun; H K Park; S H Ko; W X Wang; R V Budny; N C Luhmann Jr; K W Kim

doi:10.1063/1.4963152

Ion gyroscale fluctuation measurement with microwave imaging reflectometer on KSTAR

Rev Sci Instrum. 2016 Nov;87(11):11E134. doi: 10.1063/1.4963152.

Authors

W Lee¹, J Leem², G S Yun², H K Park¹, S H Ko¹, W X Wang³, R V Budny³, N C Luhmann Jr⁴, K W Kim⁵

Affiliations

¹ National Fusion Research Institute, Daejeon 34133, South Korea.
² Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, South Korea.
³ Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
⁴ University of California at Davis, Davis, California 95616, USA.
⁵ Kyungpook National University, Daegu 41566, South Korea.

PMID: 27910475
DOI: 10.1063/1.4963152

Abstract

Ion gyroscale turbulent fluctuations with the poloidal wavenumber k_θ ∼ 3 cm^-1 have been measured in the core region of the neutral beam (NB) injected low confinement (L-mode) plasmas on Korea superconducting tokamak advanced research. The turbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame, measured by the multichannel microwave imaging reflectometer. Linear and nonlinear gyrokinetic simulations also predict the unstable modes with the normalized wavenumber k_θρ_s ∼ 0.4, consistent with the measurement. Comparison of the measured frequencies with the intrinsic mode frequencies from the linear simulations indicates that the measured ones are primarily due to the E × B flow velocity in the NB-injected fast rotating plasmas.