The effects on the MHD stability of field line tying to the end faces of a cylindrical magnetic loop

✍ Scribed by Chang-Hyuk An

• Publisher: Springer
• Year: 1982
• Tongue: English
• Weight: 798 KB
• Volume: 75
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00153457

✦ Synopsis

We examine the magnetohydrodynamic (MHD) stability of a magnetic loop, taking into account field line tying at its foot points. We use the ideal MHD energy equation to derive a stability equation for a specific class of perturbations.

We found that for a loop with large aspect ratio (~>10) the field line tying effect is negligible to the m = 1 kink mode but important to the localized modes. The stability criterion for high rn localized modes is derived and compared with the Suydam criterion. The result shows that for the perturbation of the class studied, there are two effects of field line tying; one is a field line bending effect which is always stabilizing and the other is a shear effect which is stabilizing or destabilizing depending on the sign of the gradient of potential magnetic field. The net effect of field line tying is determined by the sum of these two effects.

The result of this work is contrary to the result of Hood and Priest, in which they found that the field line tying effect is significant to the m = 1 mode. We believe that the contradict.ion comes from their incomplete minimization of the energy equation.