Pseudo-three-dimensional turbulence in magnetized nonuniform plasma

TLDR

The derived equation closely resembles the two‑dimensional Navier–Stokes equation. The study derives a simple nonlinear equation to model pseudo‑three‑dimensional dynamics of a nonuniform magnetized plasma with Te≫Ti, incorporating 3‑D electron and 2‑D ion dynamics perpendicular to B0. Using this equation, the authors obtain a stationary drift‑wave spectrum by assuming a coexisting large‑amplitude long‑wavelength mode. The ω‑integrated k spectrum follows k^1.8(1+k^2)^−2.2 and the frequency width scales as k^3(1+k^2)^−1, matching the spectrum observed in the ATC tokamak.

Abstract

A simple nonlinear equation is derived to describe the pseudo-three-dimensional dynamics of a nonuniform magnetized plasma with Te≫Ti by taking into account the three-dimensional electron, but two-dimensional ion dynamics in the direction perpendicular to B0. The equation bears a close resemblance to the two-dimensional Navier–Stokes equation. A stationary spectrum in the frequency range of drift waves is obtained using this equation by assuming a coexisting large amplitude long wavelength mode. The ω-integrated k spectrum is given by k1.8(1+k2)−2.2, while the width of the frequency spectrum is proportional to k3(1+k2)−1, where k is normalized by cs/ωci. The result compares well with the recently observed spectrum in the ATC tokamak.