Magnetic pumping of whistler waves by tether current modulation

• Published in: Journal of Geophysical Research. B. Solid Earth Vol. 115; no. A2
• Main Authors: Sanchez-Arriaga, G., Sanmartin, J. R.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 13.02.2010; American Geophysical Union
• Subjects: Arrays; Astrophysics; Atmospheric sciences; Earth orbits; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geomagnetic field; Low earth orbits; Magnetic fields; Orbitals; Perturbation; Phase shift; Planetology; Space; Space plasmas; tether; Tethers; whistler; Whistlers; experimental studies; magnetic field; growth rates; Wave interaction; Magnetic pumping; geomagnetic field; tilt; Perturbation; turbulence; Whistler wave; Wavefront; frequency; Parametric instability; currents; phase shift; Electrodynamic tether; Earth orbit; Excitation; Plasma characteristic; Non linear wave
• ISSN: 0148-0227; 2169-9380; 2156-2202; 2169-9402
• DOI: 10.1029/2009JA014478

Magnetic excitation of whistlers by a square array of electrodynamic tethers is discussed. The array is made of perpendicular rows of tethers that carry equal, uniform, and time‐modulated currents at equal frequency with a 90° phase shift. The array would fly vertical in the orbital equatorial plane, which is perpendicular to the geomagnetic field B0 when its tilt is ignored. The array radiates a whistler wave along B0. A parametric instability due to pumping by the background magnetic field through the radiated wave gives rise to two unstable coupled whistler perturbations. The growth rate is maximum for perturbations with wave vector at angles 38.36° and 75.93° from B0. For an experiment involving a wavefront that moves with the orbiting array, which might serve to study nonlinear wave interactions and turbulence in space plasmas, characteristic values of growth rate and parameters, such as the number of tethers and their dimensions and distances in the array, are discussed for low Earth orbit ambient conditions.