Theory of the Tertiary Instability and the Dimits Shift from Reduced Drift-Wave Models
Theory of the Tertiary Instability and the Dimits Shift from Reduced Drift-Wave Models
Tertiary modes in electrostatic drift-wave turbulence are localized near extrema of the zonal velocity $U(x)$ with respect to the radial coordinate $x$. We argue that these modes can be described as quantum harmonic oscillators with complex frequencies, so their spectrum can be readily calculated. The corresponding growth rate $\gamma_{\rm TI}$ …