Enhanced Collisional Losses from a Magnetic Mirror Using the Lenard-Bernstein Collision Operator
Beam focusing and consequences for Doppler backscattering measurements
Measurement of zero-frequency fluctuations generated by coupling between Alfv茅n modes in the JET Tokamak
Abstract:
We report the first experimental detection of a zero-frequency fluctuation that is pumped by an Alfv茅n mode in a magnetically confined plasma. Core-localized Alfv茅n modes of frequency inside the toroidicity-induced gap (and its harmonics) exhibit three-wave coupling interactions with a zero-frequency fluctuation. The observation of the zero-frequency fluctuation is consistent with theoretical and numerical predictions of zonal modes pumped by Alfv茅n modes, and is correlated with an increase in the deep core ion temperature, temperature gradient, confinement factor H89,P, and a reduction in the main ion heat diffusivity. Despite the energetic particle transport induced by the Alfv茅n eigenmodes, the generation of a zero-frequency fluctuation that can suppress the turbulence leads to an overall improvement of confinement.