On the stability of rotational discontinuities
On the stability of rotational discontinuities
复制标题
关于旋转不连续性的稳定性
DOI：
10.1029/gl016i011p01257
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发表时间：
1989
影响因子：
5.2
通讯作者：
M. Scholer
中科院分区：
文献类型：
--
作者：
P. Richter;M. Scholer
利用一维自洽混合程序研究了磁场旋转180°时对称旋转间断的稳定性。发现不连续法线方向与上游磁场之间的角度Θ > 45°的旋转不连续是相对稳定的。不连续法线在x方向上，并且初始磁场仅在过渡区域中具有有限的y分量。在切向磁场的旋转的离子（左手）感的情况下，过渡区不随时间而加宽。在电子（右手）的旋转感的情况下，阻尼波列建立在由组件的旋转不连续性和不连续性的下游扩大与时间。具有较小角度Θ的旋转不连续性是不稳定的。对于Θ = 30°的旋转不连续性和电子旋转方向以及Θ = 15°的旋转不连续性和离子旋转方向的例子表明，这些不连续性分解成波。这些波在上游方向上近似以阿尔芬速度传播，因此在模拟系统中是相位稳定的。这些解体的不连续面的磁矢端图是S形的。速端图的上游部分总是右手的，下游部分总是左手的。
The stability of symmetric rotational discontinuities in which the magnetic field rotates by 180° is investigated by means of a one-dimensional self-consistent hybrid code. Rotational discontinuities with an angle Θ > 45° between the discontinuity normal direction and the upstream magnetic field are found to be relatively stable. The discontinuity normal is in the x direction and the initial magnetic field has a finite y component only in the transition region. In the case of the ion (lefthanded) sense of rotation of the tangential magnetic field, the transition region does not broaden with time. In the case of the electron (right-handed) sense of rotation, a damped wavetrain builds up in the By component downstream of the rotational discontinuity and the discontinuity broadens with time. Rotational discontinuities with smaller angles, Θ, are unstable. Examples for a rotational discontinuity with Θ = 30° and the electron sense of rotation as well as a rotational discontinuity with Θ = 15° and the ion sense of rotation show that these discontinuities disintegrate into waves. These waves travel approximately with Alfven velocity in the upstream direction and are therefore phase standing in the simulation system. The magnetic hodograms of these disintegrated discontinuities are S-shaped. The upstream portion of the hodogram is always right-handed; the downstream portion is always left-handed.