Rapid Particle Acceleration by Large-Amplitude Magnetohydrodynamic Waves

大振幅磁流体动力波的快速粒子加速

基本信息

批准号：
03680008
负责人：
OHSAWA Yukiharu
金额：
$ 1.15万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

We have studied nonlinear structure of magnetosonic waves, current driven instabilities, and particle acceleration, with special attention to effects of multi-species ions. These results have been applied to the investigation of solar energetic particles.In a plasma with two ion-species, a magnetosonic wave splits into two modes ; low- and high- frequency modes. The frequency of the low-frequency mode tends to zero as the wave number k approaches zero. On the other hand, the high-frequency mode has a finite cut-off frequency of the order of the ion cyclotron frequency. These two modes, however, are found to be described by KdV equations. This shows that KdV equations are not limited to the waves whose frequencies tend to zero as k->0. The characteristic solition widths are the ion inertal length for the low-frequency mode and the electron inertial length for the high-frequency mode.In ^3He-rich events occuring in some solar flares, the waves having frequencies close to the ^3He cyclotron frequency are expected to play an important role. Thus, we invesutigated current driven, electrostatic instabilities in a plasma whose main components are hydrogen and helium (^4He) cyclotron waves can be driven unstable with frequencies close to the ^3He cyclotron frequency.On the basis of these studies we proposed a unified theory for solar energetic particles that accounts for the mean chemical composition, ^3He-rich events, and prompt ion acceleration to relativistic energies.

我们研究了磁声波的非线性结构、电流驱动的不稳定性和粒子加速，特别关注多物种离子的影响。这些结果已应用于太阳高能粒子的研究。在具有两种离子种类的等离子体中，磁声波分裂成两种模式；低频和高频模式。当波数k接近零时，低频模式的频率趋于零。另一方面，高频模式具有离子回旋频率数量级的有限截止频率。然而，这两种模式被发现是由 KdV 方程描述的。这表明KdV方程不限于当k->0时频率趋于零的波。特征孤子宽度是低频模式的离子惯性长度和高频模式的电子惯性长度。在一些太阳耀斑中发生的^3He富事件中，波的频率接近^3He回旋频率预计将发挥重要作用。因此，我们研究了主要成分为氢和氦 (^4He) 回旋加速器波的等离子体中电流驱动的静电不稳定性，当频率接近 ^3He 回旋加速器频率时，回旋波可以被驱动不稳定。在这些研究的基础上，我们提出了一个统一理论对于太阳高能粒子，它解释了平均化学成分、^3He 富集事件，并促使离子加速到相对论能量。