Low-frequency electrostatic instability due to anti-loss-cone electrons

Abstract

The energetic anti-loss-cone electrons can drive a low-frequency electrostatic instability, propagating transverse to the ambient magnetic field, in the presence of a cold plasma. The typical real frequency and growth rates associated with this instabifity are respectively, of the order of (ωp being the proton cyclotron frequency). The instability has a transverse wavelength ⋍10ρe (ρe being the Larmor radius of energetic electrons). For the parameters pertinent to auroral plasma at 1RE, the quasi-linear analysis shows that the instability can give rise to an oscillating electric field Esat ⋍0.5−25 mV/ m and an increase of 100–103 K in the temperature of cold electrons. The instability may be relevant to recent observations of low-frequency turbulence on the auroral field lines.