Resistive ballooning modes in line-tied coronal fields

✍ Scribed by M. Velli; A. W. Hood

• Book ID: 104648214
• Publisher: Springer
• Year: 1986
• Tongue: English
• Weight: 560 KB
• Volume: 106
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00158501

✦ Synopsis

The stability of coronal arcades to localized resistive interchange modes in the ballooning ordering, including photospheric line tying, is investigated. It is found that the anchoring of magnetic footpoints in the photosphere is not sufficient to stabilise ballooning modes, once resistivity is taken into account. All configurations with a pressure profile decreasing from the arcade axis at some point are unstable, a purely growing mode being excited. The dependence of the growth rate 7 on the parameter Rm -1 ~ k 2 q, where r/is the resistivity and k the wavenumber in a direction perpendicular to the equilibrium field, can be described by a power law with varying index: for small values ofk 2 and an ideally stable field one finds 7 ~ Rm -1. As k 2 is increased or marginal stability is approached one finds y ~ Rm -1/3. The implications of these localised instabilities to the temporal evolution and overall energy balance of arcade structures in the solar corona is discussed.