Plasma turbulence of nonspecular trail plasmas as measured by a high-power large-aperture radar

摘要

[1] High-power, large-aperture radars have been used to characterize plasmas formed as meteoroids ablate in Earth's atmosphere. These plasmas are referred to as heads, the plasmas surrounding the meteoroids, and trails, the plasmas left behind by the meteoroids. A subset of trails is nonspecular trails, which are detected when the radar beam is quasi-perpendicular to the magnetic field. Radar returns from trail plasma are thought to originate from field-aligned irregularity reflections that form due to turbulence within the trail. In this paper, we present theory and analysis of plasma trail diffusion using nonspecular trails detected by the Advanced Research Project Agency Long-range Tracking and Identification Radar. These data include dual frequency, dual polarized, and high-range resolution in-phase and quadrature returns with azimuth and elevation data. We present turbulence onset times for nonspecular trails and derive comparisons to models. We compare diffusion coefficients calculated from the decay in signal return with ambipolar diffusion coefficients derived for specular meteor trails. These results, in conjunction with an analysis of the diffusion perpendicular and parallel to the magnetic field, demonstrate that the ambipolar diffusion coefficient is not a sufficient description of the turbulent diffusion in nonspecular trails and that other influences, such as external electric fields and anomalous cross-field diffusion, must be considered when calculating the diffusion coefficients of nonspecular trails. In addition, we examined these results with respect to the polarization of the returns and found similar trends between all polarizations with slight differences for the right circular return.