Hydromagnetic waves in a differentially rotating annulus. II. Resistive instabilities
- 1 October 1984
- journal article
- research article
- Published by Taylor & Francis in Geophysical & Astrophysical Fluid Dynamics
- Vol. 30 (3) , 227-239
- https://doi.org/10.1080/03091928408222851
Abstract
In part I of this study (Fearn, 1983b), instabilities of a conducting fluid driven by a toroidal magnetic field B were investigated. As well as confirming the results of a local stability analysis by Acheson (1983), a new resistive mode of instability was found. Here we investigate this mode in more detail and show that instability exists when B(s) has a zero at some radius s=s c. Then (in the limit of small resistivity) the instability is concentrated in a critical layer centered on s c . The importance of the region where B is small casts some doubt on the validity of the simplifications made to the momentum equation in I. Calculations were therefore repeated using the full momentum equation. These demonstrate that the neglect of viscous and inertial terms when the mean field is strong does not lead to spurious results even when there are regions where B is small.Keywords
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