A set of high frequency coherent (HFC) modes (f=80--250 kHz) is observed with beam emission spectroscopy measurements of density fluctuations in the pedestal of a strongly shaped quiescent H-mode plasma on DIII-D, with characteristics predicted for kinetic ballooning modes (KBM): propagation in the ion-diamagnetic drift direction; a frequency near 0.2--0.3 times the ion-diamagnetic frequency; inferred toroidal mode numbers of n~10--25; poloidal wave numbers of k_θ~0.17--0.4 cm^-1; and high measured decorrelation rates (τc^-1~ωₛ~0.5×10⁶ s^-1). Their appearance correlates with saturation of the pedestal pressure.
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Yan et al. (2011) studied this question.