磁塌缩不稳定与自生间歇磁流  

Magnetic Collapsing Instabilities and Self-Generated Intermittent Flux

作　　者：李晓卿[1] 

机构地区：[1]南京师范大学物理系,南京210097

出　　处：《天文学进展》2002年第4期337-349,共13页Progress In Astronomy

摘　　要：太阳和天体物理吸积盘中的磁场是一种空间间歇的磁流。在整个太阳上都可发现这种间歇磁流片,其中光球上90％以上的磁流呈现为强场形态,其强度为0.1～0.2T,大小为50～300km;在吸和盘中,已知脉动磁场比宏观磁场强几个数量级。 磁场的重联湮灭,导致在薄电流片区形成小尺度的磁环胞以及高涨的横等离激元。磁流和等离激元之间的非线性相互作用引起自类似塌缩,形成更为空间间歇的塌缩的磁环元胞。而横等离激元诱发的自生磁场具有调制不稳定性,导致磁场塌缩,形成高度间歇的磁流。 分别在磁流力学和等离子体动力论两种情况下,分析了这种磁塌缩不稳定性,并用于解释太阳上的间歇磁流以及寻求天体物理吸积盘中的反常粘滞。It is shown that magnetic fields in the Sun and astrophysical accretion disks are of a spatially intermittent nature. The intermittent flux fragments can be found all over the Sun, showing that more than 90% of the flux occurs in strong-field form with strengths of 0.1-0.2 T and sizes of 50~300 km in the photosphere. And the fluctuating magnetic field can be orders of magnitude stronger than the global one in accretion disks. A reconnective annihilation of the magnetic field leads to the formation of magnetic flux loop cells with small scales, followed by the enhanced transverse plasmons occurring in the thin current sheet. The nonlinear interaction between the flux and plasmons results eventually in self-similar collapse, giving rise to more spatially intermittent, collapsing magnetic loop cells. And the self-generated magnetic fields by the transverse plasmons are modulationally unstable, leading to magnetic flux collapse and forming the highly intermittent magnetic flux. Such a magnetic collapsing instabilities are analyzed in both cases of magneto-hydrodynamics and kinetic plasma physics, with their applications to solar intermittent flux and anomalous viscosity in astrophysical accretion disks, respectively.

关 键 词：磁塌缩 太阳 小尺度磁场 吸积盘 反常粘滞 

分 类 号：P142[天文地球—天体物理]