Spectrum Cascade by Mode Coupling in Drift-Wave Turbulence

The spectrum cascade by mode coupling in drift-wave turbulence occurs to larger and smaller values of $|\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}|$ rather than toward lower frequencies. This leads to the dual cascade process; energy cascades to smaller $k$ while enstrophy (square of the vorticity) cascades to larger $k$, analogous to two-dimensional hydrodynamic turbulence. However, the speed of energy condensation to $k=0$ is much slower than in the hydrodynamic case.