Observation of kinetic Alfvén waves by the FREJA spacecraft

• Published in: Geophysical research letters Vol. 21; no. 17; pp. 1847 - 1850
• Main Authors: Louarn, P., Wahlund, J. E., Chust, T., de Feraudy, H., Roux, A., Holback, B., Dovner, P. O., Eriksson, A. I., Holmgren, G.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 15.08.1994; Blackwell Publishing Ltd
• Subjects: Density; Earth, ocean, space; Electrostatic and electromagnetic waves; Exact sciences and technology; External geophysics; Fluctuation; Inertia; Ionosphere; Magnetohydrodynamics; Magnetosphere-ionosphere interactions; Magnetospheric Physics; Mathematical analysis; Particle acceleration; Physics of the magnetosphere; Spacecraft; Spikes; Turbulence; Kinetic Alfven wave; Artificial satellite; Particle acceleration; Auroral zone; Electromagnetic turbulence; Magnetosphere
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/94GL00882

It is shown that the low‐frequency (from 1 to 20 Hz) auroral electromagnetic turbulence consists of two kinds of phenomena: (1) magnetic fluctuations due to quasi‐static currents and (2) strong electric spikes (larger than 100 mV/m) with associated magnetic (30 nT) and density (dn/n ≥ 30%) fluctuations. These spikes are interpreted as kinetic Alfvén waves. They have transverse scale of the order of the electron inertia length (1 km) and then, could dissipate via the generation of a parallel electric field by finite electron mass effects. Given their strong Poynting flux (10−3 to 10−2 W/m²), they likely significantly contribute to the auroral plasma energization.