Solitary fast magnetosonic waves propagating obliquely to the magnetic field in cold collisionless plasma
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Solitary Fast Magnetosonic Waves Propagating Obliquely to the Magnetic Field in Cold Collisionless Plasma G. N. Kichigin Institute of Solar–Terrestrial Physics, Siberian Branch, Russian Academy of Sciences, ul. Lermontova 126a, Irkutsk, 664033 Russia e-mail: [email protected] Received June 16, 2015
Abstract—Solutions describing solitary fast magnetosonic (FMS) waves (FMS solitons) in cold magnetized plasma are obtained by numerically solving two-fluid hydrodynamic equations. The parameter domain within which steady-state solitary waves can propagate is determined. It is established that the Mach number for rarefaction FMS solitons is always less than unity. The restriction on the propagation velocity leads to the limitation on the amplitudes of the magnetic field components of rarefaction solitons. It is shown that, as the soliton propagates in plasma, the transverse component of its magnetic field rotates and makes a complete turn around the axis along which the soliton propagates.
DOI: 10.1134/S1063780X16010074
perturbation a rarefaction soliton. Thus, the rarefaction soliton under consideration has two components, one of which has a dip symmetric with respect to its bottom.
1. INTRODUCTION In this work, we consider steady-state nonlinear waves belonging to the fast magnetosonic (FMS) branch and propagating obliquely to a constant homogeneous magnetic field in cold collisionless plasma. Such waves have been extensively studied for a long time (see, e.g., [1, 2] and references therein). Here, we restrict ourselves to considering solitary waves—solitons. It is well known [1–3] that steady-state nonlinear waves (including solitons) in collisionless plasma form due to the balance between nonlinearity and dispersion. Depending on the dispersion law, either compression or rarefaction solitons can form in magnetized plasma. By a compression/rarefaction soliton, we mean a perturbation propagating in plasma in the form of a magnetic field hill/well. For example, in a compression soliton propagating strictly perpendicular to the magnetic field [4], the perturbed magnetic field has only one (transverse) component, the sign of which coincides with that of the unperturbed field; as a result, the field profile is bell-shaped. In the general case, the perturbed magnetic field in nonlinear perturbations has, as a rule, two components, as is, e.g., in waves propagating strictly along the magnetic field [5]. In this case, only one component has the form of a solitary wave symmetric with respect to of its center, while the other, the magnitude of which is somewhat lower, is antisymmetric. In the literature, in spite of its complicated structure, such a formation is called a soliton. We will also use this term and call such a field
Analytic soliton solutions were obtained for the cases where a nonlinear wave propagates in cold plasma strictly perpendicular [1, 4, 6] and strictly along the magnetic field [5]. Unfortunately, the equations describing solitons propagating obliquely to the magnetic field can be solved
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