Turbulence in CTX is obtained by gas injection. (a) The low density regime possesses quasiperiodic instability bursts (HEI) which evolve to the megahertz frequency range. (b) High density plasmas have steady turbulence with a high fluctuation level in the few kilohertz range.
The amplitude of mode , and the respective spatial and temporal modal decomposition. The modes for are plotted corresponding to the azimuthal mode number .
The Lyapunov spectrum for embedded dimension for the Lorenz system (inset) and density fluctuations in CTX. The largest positive Lyapunov number converges near , yielding a characteristic time of .
The ensemble-averaged floating potential spectra taken across the plasma radius, . The dashed line indicates for reference.
Structure of potential fluctuations displaying (red) and (blue) azimuthal modes. Measurements taken by probes separated azimuthally by .
Dispersion relation and growth rate from the linear contribution . The dispersion is linear at . Marginally damped modes exist in the range below approximately 10 kHz.
Power is transferred nonlinearly from high frequencies into the spectral region below where the quasicoherent structures exist.
The spectra , and the computed energy spectrum . The energy spectrum displays a power law for
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