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

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 instability are respectively, of the order of (msub(e)/msub(p))sup(1/2) Ωsub(p) and 10-3 Ωsub(p) - 10-5 Ωsub(p) (Ωsub(p) being the proton cyclotron frequency). The instability has a transverse wavelength approximately equal to 10rhosub(e) (rhosub(e) being the Larmor radius of energetic electrons). For the parameters pertinent to auroral plasma at 1Rsub(E), the quasi-linear analysis shows that the instability can give rise to an oscillating electric field Esub(sat) approximately equal to 0.5-25 mV/m and an increase of 100-1030K in the temperature of cold electrons. The instability may be relevant to recent observations of low-frequency turbulence on the auroral field lines. (author)