Volume 452, Number 1, June II 2006
|Page(s)||321 - 330|
|Published online||17 May 2006|
Tearing and Kelvin-Helmholtz instabilities in the heliospheric plasma
Department of Astronomy and Space Science, Univ. of Firenze, 50125 Firenze, Italy e-mail: email@example.com
2 Department of Physics, Univ. of Pisa, 56127 Pisa, Italy
3 Jet Propulsion Laboratory, California Institute of Technology, 91109 Pasadena, CA, USA
Accepted: 9 January 2006
We used 2.5D simulations to analyze the magnetohydrodynamic instabilities arising from an initial equilibrium configuration consisting of a plasma jet or wake in the presence of a magnetic field with strong transverse gradients, such as those arising in the solar wind. Our analysis extends previous results by considering both a force-free equilibrium and a pressure-balance condition for a jet in a plasma sheet, along with arbitrary angles between the magnetic field and velocity field. In the force-free case, the jet/wake does not contain a neutral sheet but the field rotates through the flow to invert its polarity. The presence of a magnetic field component aligned with the jet/wake destroys the symmetric nature of the fastest growing modes, leading to asymmetrical wake acceleration (or, equivalently, jet deceleration). In the case of a jet, the instability properties depend both on the magnetic field and flow gradients, as well as on the length of the jet. The results are applied to the post-termination shock jet recently found in 3D global heliospheric simulations, where our analysis confirms and explains the stability properties found in such simulations.
Key words: instabilities / magnetohydrodynamics (MHD) / plasmas / methods: numerical / Sun: solar wind
© ESO, 2006
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