WHAT CAUSES SCATTER-FREE TRANSPORT OF NON-RELATIVISTIC SOLAR ELECTRONS?
WHAT CAUSES SCATTER-FREE TRANSPORT OF NON-RELATIVISTIC SOLAR ELECTRONS?
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DOI：
10.1088/0004-637x/728/2/133
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
L. Tan;D. Reames;C. Ng;X. Shao;Linghua Wang
中科院分区：
文献类型：
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作者：
L. Tan;D. Reames;C. Ng;X. Shao;Linghua Wang
我们已经研究了非相对论性太阳电子无散射传输的原因。将电子无散射传输事件与扩散传输事件进行比较。我们检查的重点是电子角分布的能量依赖性和行星际磁场 (IMF) 功率谱密度 (PSD) 的陡峭化。在质子回旋频率附近和之上，需要分别考虑 R 模式（哨声）和 L 模式（电磁离子回旋加速器，EMIC）波的影响。由于太阳风热离子的 EMIC 波阻尼而导致的 PSD 光谱变陡变得至关重要。在快速上升-快速衰变脉冲电子事件中，我们观察到了这种陡峭化，这显着降低了高于质子陀螺频率的频率下的 PSD 水平。由此产生的光谱陡化有利于低能电子的无散射传输的发生。因此，在风/3D等离子体和高能粒子仪器/硅半导体望远镜测量的能量范围（〜25-500 keV）内，似乎存在一个电子能量窗口，穿过该窗口，较低能量电子的无散射传输将转变为较高能量电子的扩散传输。我们观察到了这种变化，并发现它与电子幂律谱破裂的发生有关。因此，从扩散电子传输到无散射电子传输的转变与从高 IMF PSD 水平到低 IMF PSD 水平的同时转变以及电子幂律能谱和 PSD 谱中相应断裂之间的联系已经得到认可。
We have examined the cause of the scatter-free transport of non-relativistic solar electrons. Electron scatter-free transport events are compared with the diffusive transport event. The emphasis of our examination is on the energy dependence of electron angular distributions and the steepening of interplanetary magnetic field (IMF) power spectral densities (PSDs). Near and above the proton gyrofrequency, the effects of both R-mode (whistler) and L-mode (electromagnetic ion cyclotron, EMIC) waves need to be taken into account separately. The PSD spectral steepening due to the EMIC wave damping by solar-wind thermal ions becomes essential. In a fast-rise–fast-decay impulsive electron event we have observed such steepening, which significantly reduces PSD levels at frequencies above the proton gyrofrequency. The spectral steepening thus produced favors the occurrence of scatter-free transport of low-energy electrons. Consequently, within the Wind/3D Plasma and Energetic Particle Instrument/Silicon Semiconductor Telescope measured energy range (∼25–500 keV), there appears to be an electron energy window, across which the scatter-free transport of lower energy electrons would change to the diffusive transport of higher energy electrons. We have observed such a change and found it is correlated with the occurrence of broken power-law spectra of electrons. Thus the connection between the transition from diffusive to scatter-free electron transport and the concurrent transition from high to low IMF PSD levels with corresponding breaks in the electron power-law energy spectrum and PSD spectrum has been recognized.