Bispectral analysis of broadband and quasi-coherent oscillations (geodesic-acoustic modes) to interpret wave-wave interactions in the T-10 Tokamak

Local fluctuations of poloidal electric field \~{ }E\textunderscore pol and density \~{ }n\textunderscore e were simultaneously measured by a heavy ion beam probe [Demers et al., 2001; Dnestrovskij et al., 1994; Melnikov et al., 2017] having a 5-slit energy analyzer that allows an estimate of the turbulent particle flux and E \texttimes B rotation velocity in the gradient zone of plasma column (r/a $=$ 0.8) [Eliseev et al., 2018]. High spatial and temporal resolution of the modern multichannel HIBP makes the HIBP an effective tool to study plasma oscillations. Previous work documented time-resolved interactions between measured plasma parameters using correlation analysis (of \~{ }E\textunderscore pol and \~{ }n\textunderscore e and cross-phase). This talk documents time-resolved interactions between measured plasma disparate-frequency modes using bicorrelation analysis (of \~{ }E\textunderscore pol and \~{ }n\textunderscore e and bi-phase) [Stauber, 1995; Riggs, 2019]. The intention is to identify the direction of energy transfer between modes (broadband, quasi-coherent).