Abstract
Axisymmetric stability of viscous resistive magnetized Couette flow is re-examined,
with the emphasis on flows that would be hydrodynamically stable according to
Rayleigh's criterion: opposing gradients of angular velocity and specific angular
momentum. In this regime, magnetorotational instabilities (MRI) may occur. Previous
work has focused on the Rayleigh-unstable regime. To prepare for an experimental
study of MRI, which is of intense astrophysical interest, we solve for global linear
modes in a wide gap with realistic dissipation coefficients. Exchange of stability
appears to occur through marginal modes. Velocity eigenfunctions of marginal modes
are nearly singular at conducting boundaries, but magnetic eigenfunctions are smooth
and obey a fourth-order differential equation in the inviscid limit. The viscous marginal
system is of tenth order; an eighth-order approximation previously used for Rayleigh-unstable
modes does not permit MRI. Peak growth rates are insensitive to boundary
conditions. They are predicted with surprising accuracy by WKB methods even for the
largest-scale mode. We conclude that MRI is achievable under plausible experimental
conditions using easy-to-handle liquid metals such as gallium.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
86 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献