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Low frequency waves in plasmas with spatially varying electron temperature
Authors:P Guio  S Børve  H L Pécseli  J Trulsen
Institution:(1) The Auroral Observatory, Institute of Physics, University of Tromsø, N-9037 Tromsø, Norway;(2) Institute for Theoretical Astrophysics, University of Oslo, Box 1029, Blindern, N-0315, Oslo, Norway;(3) Physics Department, University of Oslo, Box 1048, Blindern, N-0316, Oslo, Norway;(4) Institute for Theoretical Astrophysics, University of Oslo, Box 1029, Blindern, N-0315, Oslo, Norway
Abstract:Low frequency electrostatic waves are studied in magnetized plasmas with an electron temperature which varies with position in a direction perpendicular to the magnetic field. For wave frequencies below the ion cyclotron frequency, the waves need not follow any definite dispersion relation. Instead a band of phase velocities is allowed, with a range of variation depending on the maximum and minimum values of the electron temperature. Simple model equations are obtained for the general case which can be solved to give the spatial variation of a harmonically time varying potential. A simple analytical model for the phenomenon is presented and the results are supported by numerical simulations carried out in a 2.5-dimensional particle-in-cell numerical simulation. We find that when the electron temperature is striated along B0 and low frequency waves (ohgrLtOHgrci) are excited in this environment, then the intensity of these low frequency waves will be striated in a manner following the electron temperature striations. High frequency ion acoustic waves (ohgrLtOHgrci) will on the other hand have a spatially more uniform intensity distribution.
Keywords:Ionosphere (plasma temperature and density)  Radio science (waves in plasma)  Space plasma physics (numerical simulation studies)
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