Abonnement à la biblothèque: Guest
Portail numérique Bibliothèque numérique eBooks Revues Références et comptes rendus Collections
Telecommunications and Radio Engineering
SJR: 0.202 SNIP: 0.2 CiteScore™: 0.23

ISSN Imprimer: 0040-2508
ISSN En ligne: 1943-6009

Volume 78, 2019 Volume 77, 2018 Volume 76, 2017 Volume 75, 2016 Volume 74, 2015 Volume 73, 2014 Volume 72, 2013 Volume 71, 2012 Volume 70, 2011 Volume 69, 2010 Volume 68, 2009 Volume 67, 2008 Volume 66, 2007 Volume 65, 2006 Volume 64, 2005 Volume 63, 2005 Volume 62, 2004 Volume 61, 2004 Volume 60, 2003 Volume 59, 2003 Volume 58, 2002 Volume 57, 2002 Volume 56, 2001 Volume 55, 2001 Volume 54, 2000 Volume 53, 1999 Volume 52, 1998 Volume 51, 1997

Telecommunications and Radio Engineering

DOI: 10.1615/TelecomRadEng.v52.i12.10
pages 1-6

Problems of Evolution in Magnetohydrodynamics

Alevtina Alexandrovna Aleksandrova
Kharkov National University of Radio Engineering and Electronics, 14, Lenin Ave, Kharkov, 61166, Ukraine
Yu. N. Aleksandrov
Kharkov National University of Radio Engineering and Electronics, 14, Lenin Ave, Kharkov, 61166, Ukraine


We consider low-frequency oscillations that can be excited and propagate in plasma. We restrict our study to the case of sufficiently slow macroscopic processes. We need this assumption in order to use the hydrodynamic description of these processes, which, as well as the electromagnetic description of the field, is contained in the magnetohydrodynamics equations [1] for the velocity of the medium u(r, t), the strength of the magnetic field b(r, t), and the density of the medium ρ(r, t). In linear magnetohydrodynamics, a wave packet consists of characteristic waves of the following seven types: two accelerated magnetoacoustic, two decelerated magnetoacoustic, two Alfen, and one entropic waves. In Alfen waves, we have zero perturbations of medium density and entropy and of the components of the medium and the magnetic field that lie in the plane passing through the directions of the unperturbed magnetic field Bo and wave propagation. In magnetoacoustic waves, we have zero perturbations of the entropy and components of the medium and of the magnetic field that are perpendicular to the direction of wave propagation and to Bo. Hence magnetoacoustic waves are isoentropic and plane polarized. Finally, in the entropic wave, only the density and entropy are perturbed. The above wave packet is described by the state vector ψ, which, at each point M(x, y, z) in space and at each time instant t, can be determined by the domains of the initial and boundary conditions for these waves.