Hydromagnetic waves and cosmic-ray diffusion theory
Hydromagnetic waves and cosmic-ray diffusion theory
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水磁波和宇宙射线扩散理论
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
H. Voelk
中科院分区：
文献类型：
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作者：
M. Lee;H. Voelk
研究了宇宙射线在水磁场中的俯仰角（和能量）扩散。处理仍然严格地保持在拟线性近似范围内。结果表明，磁涨落的各向同性功率谱张量的普遍假设在这种情况下要求阿尔芬波谱和磁子波谱的形式和大小相等——这种情况通常是不可能的。以典型太阳风为例，计算了不同波类型下回旋共振和朗道共振对俯仰角扩散系数的相对贡献。由于这种近似中的朗道共振也不会导致粒子反射，因此，要克服宇宙射线在90度俯仰角附近的准线性散射理论的众所周知的困难，确实需要适当地考虑非线性粒子轨道。
Pitch-angle (and energy) diffusion of cosmic rays in hydromagnetic wave fields is considered. The treatment remains strictly within the quasi-linear approximation. It is shown that the popular assumption of an isotropic power spectrum tensor of magnetic fluctuations requires in this case equal forms and magnitudes of Alfven and magnetosonic wave spectra - a situation which is generally unlikely. The relative contributions to the pitch-angle diffusion coefficient from the cyclotron resonances and Landau resonance due to the different types of waves are evaluated for a typical situation in the solar wind. Since the Landau resonance in this approximation also does not lead to particle reflections, a proper consideration of the nonlinear particle orbits is indeed necessary to overcome the well-known difficulties of quasi-linear scattering theory for cosmic rays near 90 deg pitch angle.