TJ-II: Influence of Alfven Eigenmodes in edge turbulence and Zonal Flows: Difference between revisions

Fast ions have been found to impact plasma confinement. While most of previous research have been focussed on the excitation and impact of fast ions modes in plasma performance, because of the drain of energy related to fast particle losses with a concomitant potential damages in the plasma facing components, there is a growing interest on the impact on fast particles on plasma turbulence and self-organization phenomena <ref>A. Di Siena et al « Electromagnetic turbulence suppression by energetic particle driven modes” 2019 Nucl. Fusion 59 124001</ref> <ref>S. Mazzi, et al. Towards enhanced performance in fusion plasmas via turbulence suppression by MeV ions, submitted to Nature Physics</ref>[1, 2].

The unique TJ-II experimental set-up using a dual HIBP has shown that, in some conditions, long range correlations (LRC) are detected both at the AE frequencies and low frequencies (< 10 kHz). LRC are observed in plasma potential fluctuations but not in density fluctuations as expected in zonal flow structures [3]. Recent experiments have shown clear evidence non-linear coupling between Alfven modes and broadband turbulence as well as some hints of coupling between low frequency Zonal Flows and broad-band turbulence using edge probes measurements [3]. These results were obtained in plasma regimes with steady-state AEs activity in a time scale of about six energy confinement times.