Plotted in black is the DBS phase power spectrum, ensemble-averaged over 500 ms, of a steady-state -mode plasma. The spectrum primarily goes as , except for a coherent mode that is present (a GAM in this case), then rolls over at high frequencies where various effects compete.
(a) Spectrogram of the DBS phase at , showing a flow oscillation from a GAM as the GAM’s frequency is modulated by sawtooth heat pulses. (b) Electron temperature from ECE at the same radial location.
(a) Coherency of the DBS phase between two DBS channels at toroidal locations separated by 180°, radially aligned at , and ensemble averaged over 400 ms. (b) Crossphase between the same two channels.
The crossphase, , among the phase of seven DBS channels at the GAM frequency plotted against , ensemble averaged over 400 ms, showing outward radial propagation of the GAM. The center channel of DBS-5 is the reference.
Comparison of cross-correlation of reflectometer phase and ECE data to the reflectometer amplitude from the same channel and the same ECE signal, ensemble averaged over 400 ms using 975 records. Error bars omitted for clarity. (a) Comparison of the coherency. (b) Comparison of the crossphase angle, , using the reflectometer as the reference signal.
The changes to the crossphase between electron density and temperature fluctuations, , with increasing electron temperature at , calculated with reflectometer amplitude correlated with an ECE channel. The frequency at which the maximum coherency occurs for each pair is used to calculate the crossphase and error bars.
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