Scattering of electromagnetic waves by vortex density structures associated with interchange instability: Analytical and large scale plasma simulation results

Abstract

The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.

Horseshoes in the High‐Latitude Ionosphere

“…The plasma convection in this study is simplified as the high‐latitude horizontal drift by ignoring other contributions to drift. However, to examine LCSs globally, a study would need to be conducted with modeled plasma drifts including electric Pedersen drift, gravitational Pedersen drift, pure gravitational drift, and parallel mean flow (Atul et al, ; Sotnikov et al, ). This would likely lead to a three‐dimensional flow field, requiring 3‐D LCS analysis, which ITALCS does not currently treat.…”

“…A polar cap patch is often associated with ionospheric plasma density irregularities varying from 100 m to several kilometers scale size that adversely affect Global Navigation Satellite System (GNSS) service (Moen et al, ) by causing scintillation, a rapid fluctuation in signal amplitude and phase (Datta‐Barua et al, ; Zhang, Zhang, Lockwood, et al, ; Zhang, Zhang, Moen, et al, ). The mechanism for scintillation is electromagnetic wave scattering due to variations in density (Sotnikov et al, ). Polar cap patch scintillations are believed to arise due to a number of possible instability mechanisms (Atul et al, ; Burston et al, ; Moen et al, ).…”

“…For this analysis, the flow of interest is the plasma drift convection as a flow field at high latitudes in both hemispheres. While in general plasma drift is a superposition of electric Pedersen drift, gravitational Pedersen drift, pure gravitational drift, and parallel mean flow (Atul et al, ; Sotnikov et al, ), in the high‐latitude region above 50° geomagnetic latitude, the plasma drift is dominated by drift due to the absence of vertical shears (Anderson et al, ; Kirchengast, ). The drift is governed by the local electric and magnetic fields: where V is an electrostatic potential function and is the magnetic field.…”

SuperDARN Evidence for Convection‐Driven Lagrangian Coherent Structures in the Polar Ionosphere

“…Polar cap patches are known to lead to scintillation, which is a rapid fluctuation in the signal amplitude or phase of radio waves (Yeh & Liu, ). Scintillation happens as a result of the scattering of the electromagnetic waves due to changes in electron density (Sotnikov et al, ). Scintillation can degrade the performance of the Global Navigation Satellite System (GNSS) by causing loss of satellite lock and may lead to positioning errors (Moen et al, ; Pi et al, ).…”

“…In general, plasma motion has components parallel and perpendicular to the local magnetic field. The motion is the sum of the electric Pedersen drift, gravitational Pedersen drift, pure gravitation drift, and parallel mean flow (Atul et al, ; Sotnikov et al, ). Specifically, in the high‐latitude ionosphere, plasma motion is coupled to the magnetosphere and the IMF.…”