Kinetic model of electron heating by turbulent electric field in the E region

Abstract

[1] Numerous radar observations demonstrate anomalously strong electron heating in polar electrojets during magnetic storms. The effect correlates with strong convection electric field. Anomalous heating of electrons is caused by turbulent electric fields developing in the E region due to the Farley-Buneman instability. A quantitative model of the effect is proposed. Numerical computations are based on a kinetic code. A good agreement of the theoretical results with the existing observations supports the physical ideas underlying the model.

Imaging radar observations of Farley Buneman waves during the JOULE II experiment

“…Mode coupling maintains a statistical steady state whereby the primary waves are operating near the linear threshold for marginal stability. Although their simulations are two dimensional, similar behavior is predicted by the semi-heuristic model of Milikh and Dimant (2002) which includes coupling to off-perpendicular modes. Off-perpendicular wave modes contribute substantially to wave heating, causing the electron temperature and the ion acoustic speed to increase in a manner consistent with the empirical formula of Nielsen and Schlegel (1985).…”

“…One of the more successful findings continues to be that primary Farley Buneman waves maintain a state of marginal linear stability. Not only does this account for the fact that they propagate with phase speeds near the ion acoustic speed, it also predicts their magnetic aspect width to the degree required to account for the wave heating observed (Milikh and Dimant, 2002). Once the primary waves achieve marginal linear stability, they immediately generate a spectrum of secondary waves that 1) extract energy from the primaries, limiting their amplitude, 2) heat the ionosphere (particularly secondaries with finite parallel wavenumbers), increasing the threshold speed, and 3) disrupt the convection around the primary waves, limiting their phase speeds in the manner depicted by Otani and Oppenheim (2006).…”

“…Coherent scatter spectra from E-region auroral irregularities are clearly affected by the magnitude and direction of the convection electric field, but the relationship is not so direct as in the case of F-region FAIs, and the prospects of inferring electric fields from the radar data are unresolved (St.-Maurice et al, 1981;Nielsen and Schlegel, 1985;Robinson, 1986;Foster and Erickson, 2000;Milikh and Dimant, 2002;Nielsen et al, 2002;Uspensky et al, 2003Uspensky et al, , 2004Makarevich et al, 2006). Using imaging radar and rocket data from the JOULE I experiment, a precursor to this one, Bahcivan et al (2005) found a cosine relationship on flow angle (angle between convection and the radar line of sight) for the Doppler shift and an approximately sinusoidal relationship for the spectral width.…”

Combined radar observations of equatorial electrojet irregularities at Jicamarca

“…(A4) reveals that electron heating effects are minor in the altitude range of interest, where the ratio of the electron collision frequency to gyrofrequency is small. Heating by wave electric fields parallel to B are much more important, although their effect has been neglected here (Milikh and Dimant, 2002). Cooling effects, meanwhile, are apt to be significant, particularly at VHF frequencies, as the product ν en δ e is of the order of 10 2 in the lower E-region.…”

On the generation of large wave parallel electric fields responsible for electron heating in the high‐latitude E region

“…Recent findings on this topic are given in a series of papers by Milikh and Dimant [2002, 2003a, 2003b, who performed a numerical computation of the electron distribution function (EDF) driven by a parallel electric field, whose magnitude was determined based on a heuristic assumption involving the marginal stability of the Farley-Buneman waves and an assumed distribution of wave amplitudes versus angle with the magnetic field. After including various cooling mechanisms, they computed the effective electron temperature for a given E c .…”