关于太阳日冕磁环的稳定性

本文指出:在过去多数的日冕磁环稳定性的研究中,都存在一个未作说明、却又不容忽视的问题,即无形中都在磁环边缘处用了固壁边界条件,而它的采用与否对结果影响极大;另外在这些研究中只考虑m=1的模式也是不够的。这些问题都有待于进一步研究。 

ON THE STABILITY OF CORONAL MAGNETIC LOOPS

In this paper, it is pointed out that in most of the previous works about the stability of coronal magnetic loops, a rigid boundary condition is used (although sometimes without being mentioned) at the edge of a loop, which has a great influence on the result too large to be ignored, even if the pressure gradient is favourable. On the other hand, corona conditions are quite different from that in laboratories. Is it proper to use the rigid boundary condition at the edge of a loop? And what is the mechanism that makes the condition realized? They are still the questions open to further discussions.Besides, if m=1 is stable, according to Newcomb's theorem, it is unnecessary to consider the modes of m> 1; but if it is not stable, it will not be enough to examine m= 1 only. And this article shows that, sometimes, the modes of m > 1 may be more instable.Instead of using a marginal stability analysis such as many authors did, the MHD momentum equation of compressible fluid is used in this paper, so that both the instability region and the growth rate of instability can be obtained at the same time. In addition. the difficulties associated with the singularity in marginal stability analysis could then be avoided.