Interplanetary Plasma Scattering Diagnostics from Anisotropy-time Profiles of Solar Energetic Particles
Interplanetary Plasma Scattering Diagnostics from Anisotropy-time Profiles of Solar Energetic Particles
复制标题
根据太阳高能粒子的各向异性时间剖面进行行星际等离子体散射诊断
DOI：
10.2174/1876534300902010001
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
W. Dröge
中科院分区：
文献类型：
--
作者：
R. Schlickeiser;S. Artmann;W. Dröge
太阳粒子事件的各向异性-时间剖面为高能带电粒子的行星际等离子体散射参数提供了强大的诊断工具。在轴对称 MHD 湍流中太阳粒子输运的弱聚焦极限下，粒子各向异性由两种贡献组成，即流动贡献和康普顿贡献，分别由粒子相空间密度各向同性部分的平行空间梯度和动量梯度产生。这些梯度可以根据太阳粒子的时间相关聚焦输运方程的适当解来计算。对于具有恒定聚焦长度和粒子的点状瞬时注入的一维时间相关聚焦传输方程的解的说明性情况，在由具有相等磁螺旋性的等谱无阻尼平板阿尔文波组成的 MHD 湍流中分析计算了流和康普顿-获取对各向异性时间分布的贡献。康普顿-盖廷贡献与行星际阿尔文速度与太阳粒子速度之比成正比，因此远小于观测到的弱相对论性太阳粒子的流贡献。在时间 t < tM 时各向异性值消失后，流各向异性在 tM = t 0 + (zz0)/v 时突然达到其最大值 AS,max = 3 2 + (p) 2L。随后，流各向异性减小 (tt0) � 1
The anisotropy-time profile of solar particle events provides a powerful diagnostics tool to the interplanetary plasma scattering parameters of energetic charged particles. In the weak focusing limit of the transport of solar particles in axisymmetric MHD turbulence, the particle anisotropy consists of two contributions, the streaming and the Compton- Getting contribution, resulting from the parallel spatial gradient and the momentum gradient of the isotropic part of the particles' phase space density, respectively. These gradients can be calculated from the appropriate solution to the time- dependent focused transport equation of solar particles. For the illustrative case of the solution of the one-dimensional time-dependent focused transport equation with a constant focusing length and a point-like instantaneous injection of particles the streaming and Compton-Getting contributions to the anisotropy-time profile are analytically calculated in MHD turbulence consisting of isospectral undamped slab Alfven waves for equal magnetic helicity. The Compton-Getting contribution scales proportional to the ratio of interplanetary Alfven speed to solar particle speed, and therefore is much smaller than the streaming contribution for the observed mildly relativistic solar particles. After vanishing anisotropy values at times t < tM the streaming anisotropy suddenly attains its maximum value AS,max = 3 2 + (p) 2L at tM = t 0 + (zz0)/v. At later times the streaming anisotropy decreases (tt0) � 1