Plasma instabilities in meteor trails: 2‐D simulation studies

Abstract

Field‐aligned plasma density irregularities detected as nonspecular echoes by radars with large aperture‐power products indicate the presence of plasma turbulence within meteor trails. This paper presents two‐dimensional simulations of meteor trail instabilities and compares these results with theory and observations. In particular, this paper describes techniques for simulating trail turbulence and then discusses two sample cases using realistic plasma density gradients, masses, and atmospheric conditions appropriate for a 102‐km altitude. In the first case, the trail lies along the geomagnetic field, B. In the second, it lies perpendicular to B and is subject to a small external electric field pointing parallel to it. These cases show the spontaneous development of instabilities leading to turbulence and field‐aligned irregularities. These irregularities can create nonspecular echoes with broad spectral lines and small Doppler shifts similar to those observed by radars with large aperture‐power products. The simulations also show turbulence‐enhanced cross‐field diffusion rates. Finally, the paper describes simulations of trails containing multiple ion species and shows how turbulent mixing greatly reduces species fractionation.