AN INTRODUCTION TO THE THEORY OF DIFFUSIVE SHOCK ACCELERATION OF ENERGETIC PARTICLES IN TENUOUS PLASMAS
AN INTRODUCTION TO THE THEORY OF DIFFUSIVE SHOCK ACCELERATION OF ENERGETIC PARTICLES IN TENUOUS PLASMAS
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DOI：
10.1088/0034-4885/46/8/002
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发表时间：
1983-01-01
影响因子：
18.1
通讯作者：
DRURY, LOC
中科院分区：
文献类型：
--
作者：
DRURY, LOC
扩散冲击加速的中心思想是从微观和宏观的观点;适用于无反应的测试粒子在一个稳定的平面冲击的机制示出产生一个幂律谱动量的斜率，最低阶的等离子体粒子速度的比率，只取决于在冲击的压缩。相关的时间尺度被发现（也通过宏观和微观的方法）和球形冲击的问题，例如点爆炸和星风终结者，奇异摄动理论处理。然后研究包括粒子反应的效果。它表明，如果散射是由于共振波，这些可以迅速增长，未知的后果。对可能的定常修正激波结构进行了分类，并找到了广义Rankine-Hugoniot条件，根据精确解（如果不是人为的话）、高能渐近展开式和Blandford的摄动展开式讨论了谱的修正。指出对于非常强的冲击，不可能存在稳定解;简要讨论了可能的时间依赖性。
The central idea of diffusive shock acceleration is presented from microscopic and macroscopic viewpoints; applied to reactionless test particles in a steady plane shock the mechanism is shown to produce a power law spectrum in momentum with a slope which, to lowest order in the ratio of plasma to particle speed, depends only on the compression in the shock. The associated time scale is found (also by a macroscopic and a microscopic method) and the problems of spherical shocks, as exemplified by a point explosion and a stellar-wind terminator, are treated by singular perturbation theory. The effect of including the particle reaction is then studied. It is shown that if the scattering is due to resonant waves these can rapidly grow with unknown consequences. The possible steady modified shock structures are classified and generalised Rankine-Hugoniot conditions found. Modifications of the spectrum are discussed on the basis of an exact, if rather artificial, solution, a high-energy asymptotic expansion and a perturbation expansion due to Blandford. It is pointed out that no steady solution can exist for very strong shocks; the possible time dependence is briefly discussed.