Gradient drift instability in high latitude plasma patches: Ion inertial effects

Radially sheared azimuthal flows and turbulent transport in a cylindrical plasma

“…However, this viscous damping plays an insignificant role in the damping of the large-scaled shear flows. Thus in our linear analysis we include an effective ion-neutral drag on the ions in a form identical to that used in recent studies of the ionosphere, 38 but we have neglected viscous damping which will affect the high-k spectral region (and thus is not important for the consideration of the origins of the large-scale shear flows).…”

Three‐dimensional structuring characteristics of high‐latitude plasma patches

“…The evolution of the structuring of the density and potential in the nonlinear simulations of the gradient drift instability with inertial effects for the highlatitude plasma patches has been discussed previously by Gondarenko and Guzdar [1999]. It was shown that the initial cross-field elongated structures driven by the gradient drift instability are unstable to the KelvinHelmholtz instability and to the generation of sheared flows.…”

Plasma patch structuring by the nonlinear evolution of the gradient drift instability in the high‐latitude ionosphere

“…In our simulations we use the ion‐neutral collision frequency profile with ν in ∼ 0.1 s −1 at the height of the density peak (near the F peak height) shown in Figure 1a. The electron continuity and the charge neutrality (“vorticity”) equations [ Drake et al , 1988] with polarization drift terms representing the inertial effects give rise to three dimensionless parameters [ Gondarenko and Guzdar , 1999, 2001] β, ν, and R defined as where L ⊥0 and L z 0 are the characteristic scale lengths of the patch in the directions transverse and parallel to the magnetic field, L n is the density gradient scale length, V n is the neutral wind velocity, and N 0 is the density of the uniform background. For typical F ‐region parameters Ω e ∼ 10 7 rad / s ; Ω i ∼ 10 2 rad / s ; ν ei ∼ 10 3 s −1 ; ν in ∼ 0.1 s −1 , and with the characteristic scale lengths L ⊥0 = 8 km and L z 0 = 179 km, β ∼ 2 × 10 4 .…”

“…The inclusion of the three‐dimensional (3‐D) effects into our model [ Guzdar et al , 1998] resulted in slowing down the structuring so that the evolution occurred on time scales comparable to the observations. The effects of parallel dynamics and the inertial effects [ Gondarenko and Guzdar , 1999], which are responsible for the generation of the secondary Kelvin‐Helmholtz (KH) and tertiary shear‐flow instabilities, prevent the patch from disintegrating for hours. It was shown [ Gondarenko and Guzdar , 2001] that anisotropy prevailed in the density and velocity spectra and the ion‐inertial effects tend to isotropize the spectra as was predicted in the simulation study by Mitchell et al [1985].…”

“…An important finding of our previous studies, first for the collisional GDI [ Guzdar et al , 1998] when the basic structuring occurred in highly elongated “fingers” and next for the simulations with the ion inertial effects [ Gondarenko and Guzdar , 1999, 2001, 2003] when the finger‐like structures are unstable to secondary instabilities, is that the initial instability does develop on the trailing edge, but the irregularities do not remain localized on the edges of the plasma patch. In this study we demonstrate that the instability, in its full nonlinear development, penetrates through the entire patch and reaches the leading edge over the realistic time scale.…”