Ideal Instabilities in a Magnetic Flux Tube

  1. C. T. Russell,
  2. E. R. Priest and
  3. L. C. Lee
  1. Giorgio Einaudi

Published Online: 21 MAR 2013

DOI: 10.1029/GM058p0043

Physics of Magnetic Flux Ropes

Physics of Magnetic Flux Ropes

How to Cite

Einaudi, G. (1990) Ideal Instabilities in a Magnetic Flux Tube, in Physics of Magnetic Flux Ropes (eds C. T. Russell, E. R. Priest and L. C. Lee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM058p0043

Author Information

  1. Dipartimento di Astronomia e Scienza dello Spazio, Universita' di Firenze, 50125 Firenze, Italy

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1990

ISBN Information

Print ISBN: 9780875900261

Online ISBN: 9781118663868

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Keywords:

  • Solar photosphere;
  • Magnetic flux;
  • Astrophysics

Summary

In this paper we will review some theoretical aspects of ideal instabilities which arise in a axially symmetric magnetic flux tube. The interest in the stability of these structures derives from the fact that their observed lifetime in astrophysical plasmas is often much longer than the relevant hydromagnetic timescale and that they exhibit a dynamical active behavior. Therefore these structures must be globally stable with respect to fast destructive instabilities and, at the same time, must allow some local, non-disruptive process to take place. We will first of all classify the ideal instabilities in terms of their axial and azimuthal wave numbers and describe how the energy principle and normal mode approaches can lead to information on the stability properties of the modes. We will then outline the importance of the axial boundary conditions and show that, when these conditions are taken into account, the nature of the instability strongly depends on the topology of the equilibrium magnetic field. Finally we will discuss the effects of the unstable modes on the magnetic tube.