I1-S5 · Extension of GAM theory to Helical SystemsWatari, Testuo1) Abstract GAM oscillations, whose existence have been reported first as early as in 1986, is now gathering attention. Electrostatic fluctuations are divided into those in high and low frequency ranges. Drift waves belong to the former and the GAM oscillations belongs to the latter with other residual zonal flows. The interaction of the fluctuations in these two frequency ranges is broadly accepted as key mechanisms to determine the turbulence and governs the transports. The existence of Zonal flows including GAM have been recently evidenced in tokamak experiments in DIII-D and JIPP-TII U by using developed fine diagnostics BES and HIBP, respectively. Similar oscillations were found also in a helical device CHS by use of a dual HIBP. The most significantly, these papers indicate that the associated flows have rather narrow radial structure with the shearing rates attaining the decorrelation times. The present paper addresses a problem, if a GAM oscillation can be found in theory as it is extended to cover helical systems, which so far has been applied to tokamaks.
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