Macro-scale temperature fluctuations, which have long radial correlation length (of the order of the plasma radius), have been discovered on Large Helical Device (LHD). In this paper, non-linear coupling between the long-range fluctuations and microscopic fluctuations is investigated using cross bi-coherence analysis. The significant cross bicoherence between long-range fluctuations and micro-fluctuations is observed in the range of frequency f < 100kHz, where f is the frequency of microscopic fluctuations. It is found that the squared bi-coherence and bi-phase for this three-wave coupling is weakly dependent on the frequency of microscopic fluctuations. These observations demonstrate that the microscopic fluctuations are coherently interacting with long-range fluctuations.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)