Nonlinear mechanism of the generation of lower hybrid waves in cosmic plasmas

1Yukhimuk, AK, 2Fedun, VN, 3Yukhimuk, VA, 2Fal'ko, OG, 1Sirenko, EK
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
2Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
3Taras Shevchenko National University of Kyiv, Kyiv, Ukraine; Newcastle University , Newcastle, Australia
Kosm. nauka tehnol. 1998, 4 ;(5):41–45
Section: Space and Atmospheric Physics
Publication Language: Russian
A new nonlinear mechanism of the generation of kinetic Alfven waves and lower hybrid waves in magnetized plasma with a small plasma parameter (β =8πnT/B0 2<1) is investigated. The parametric instability, where the whistler wave is the pumping wave, is considered as the generation mechanism. Two-fluid magnetohydro-dynamics is used for describing the nonlinear parametric interaction of waves. A nonlinear dispersion equation for the coupling of the lower hybrid and kinetic Alfven waves is found. We defermined also the instability growth rate у and the amplitude threshold value for the pump wave. The investigation suggests that taking into account the kinetic effects in the Alfven waves (the finite ion Larmour radius and the electron inertia length) is essential for parametric interaction of waves. It is well known that whistlers modes are use for additional plasma heating. The idea of plasma heating throunh the parametric decay implies that the energy is transmitted to plasma from waves. Very often the products of the decay can be absorb more effectively than the pump wave itself. Thus the kinetic Alfven waves interact actively with plasma particles and heat the plasma. The lower hybrid waves also interact actively with ions and increase their energy component perpendicular to the external magnetic field. They may be responsible for the temperature anisotropy and acceleration of heavy ions. Our results are used for analyzing experimental data for cosmic plasmas.
Keywords: atmospheric physics, cosmic plasmas, mechanisms of waves generation
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