A THEORY OF BIMODAL ACCELERATION OF PICKUP IONS BY COMPRESSIVE SOLAR WIND TURBULENCE UNDER PRESSURE BALANCE
A THEORY OF BIMODAL ACCELERATION OF PICKUP IONS BY COMPRESSIVE SOLAR WIND TURBULENCE UNDER PRESSURE BALANCE
复制标题
压力平衡下压缩太阳风湍流拾取离子双峰加速理论
DOI：
10.1088/0004-637x/756/2/129
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
R. Schlickeiser
中科院分区：
文献类型：
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作者：
Ming Zhang;R. Schlickeiser
最近的研究表明，粒子通过一系列压缩等离子体波的随机加速是有效和快速的。它的速度可能太快，以致加速的粒子所产生的压力可能反过来改变波的振幅，以防止粒子产生爆炸的压力。我们称之为压力平衡。在本文中，我们考虑到这样一个事实，即由于等离子体波或湍流可能具有间歇性，粒子的主动加速只占用有限的空间体积。我们提出了一种双峰加速度理论，该理论将活跃和非活跃加速度区域的粒子群分开处理，并允许两个群体有效地交换粒子。在压力平衡条件的要求下，我们证明了系统自动产生加速粒子的v−5稳态分布解。研究发现，在小体积的强粒子加速下，v−5分布更稳定，更容易实现。这些性质解释了为什么v - 5分布通常在空间中被观察到。我们将我们的模型应用于整个日球层的拾取离子传播和加速。我们的结果可以非常详细地再现各种观测结果。我们还发现，这种机制可能是在日鞘深处产生异常宇宙射线的原因。
Recently, it was demonstrated that stochastic acceleration of particles going through a series of compressive plasma waves can be efficient and fast. It could be too fast so that the pressure built up by the accelerated particles may in turn modify the amplitude of waves to prevent the particles from having an exploding pressure. We call this condition pressure balance. In this paper, we take into account the fact that active acceleration of particles only occupies a limited volume of space due to a possible intermittent nature of plasma waves or turbulence. We develop a bimodal acceleration theory that treats the populations of particles in the active and inactive acceleration regions separately and allows the two populations to exchange particles efficiently. Under the requirement of the pressure balance condition, we show that the system automatically produces a solution of v−5 steady state distribution for the accelerated particles. It is found that the v−5 distribution is more robust and easier to achieve with a small volume of intense particle acceleration. These properties explain why the v−5 distribution is commonly observed in space. We apply our model to pickup ion propagation and acceleration throughout the entire heliosphere. Our results can reproduce various observations in some great detail. We also found that this mechanism could be responsible for producing anomalous cosmic rays deep in the heliosheath.