Ion gyroscale fluctuation measurement with microwave imaging reflectometer on KSTAR

Ion gyroscaleturbulent fluctuations with the poloidal wavenumberkθ∼ 3 cm−1 have beenmeasured in the core region of the neutral beam (NB) injected low confinement(L-mode) plasmas on Korea superconducting tokamak advanced research. Theturbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame,measured by the multichannel microwave imaging reflectometer. Linear and nonlineargyrokinetic simulations also predict the unstable modes with the normalized wavenumberkθρs∼ 0.4, consistent with themeasurement. Comparison of themeasured frequencies with the intrinsic mode frequencies from the linear simulations indicates that themeasured ones are primarily due to theE×Bflow velocity in the NB-injected fast rotating plasmas.
Source: Review of Scientific Instruments - Category: Physics Authors: Source Type: research