Measurement of the energy distribution of trapped and free electrons in a current-free double layer
Measurement of the energy distribution of trapped and free electrons in a current-free double layer
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DOI：
10.1063/1.2803763
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发表时间：
2007-11
影响因子：
2.2
通讯作者：
Kazunori Takahashi;C. Charles;R. Boswell;T. Kaneko;R. Hatakeyama
中科院分区：
文献类型：
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作者：
Kazunori Takahashi;C. Charles;R. Boswell;T. Kaneko;R. Hatakeyama
在双层上游的高电势等离子体中，测得的电子能量分布函数 EEDF 显示出与双层电势下降相对应的能量断裂处斜率的非常明显的变化。能量较低的电子是麦克斯韦电子，温度为 8 eV，而能量较高的电子的温度为 5 eV。下游等离子体中的 EEDF 温度为 5 eV。在通过减速场能量分析仪的分析来检测双层和加速离子束的压力范围内，双层的强度对应于EEDF断裂中斜率变化的能量。我们推断下游电子来自上游电子，这些电子具有足够的能量来克服双层电势，并且只需要单个上游等离子体源来维持这种现象。 © 2007 美国物理研究所。 DOI：10.1063/1.2803763 太空中的高能带电粒子被认为可以通过费米提出的机制、波以及最近的双电层 DL 来加速。 1-3 虽然从卫星探测器获得的一些实验数据是可用的，但它们很少足以完全开发此类空间 DL 的自洽模型，并且必须对加速和捕获粒子分布函数的形式做出假设。 Perkins 和 Sun 预测了无电流双层解决方案的存在，4，在他们的预测之后不久，电流驱动的实验室双层就以无电流“模式”建立起来了，5-7 证实了这一预测。最近，通过实验发现了一类新的无电流双层
In the high potential plasma, upstream of the double layer, the measured electron energy distribution function EEDF shows a very clear change in slope at energies break corresponding to the double layer potential drop. Electrons with lower energy are Maxwellian with a temperature of 8 eV, whereas those with higher energy have a temperature of 5 eV. The EEDF in the downstream plasma has a temperature of 5 eV. Over the range of pressures wherein the double layer and accelerated ion beam are detected by analysis of a retarding field energy analyzer, the strength of the double layer corresponds to the energy where the slope changes in the EEDF break. We deduce that the downstream electrons come from upstream electrons that have sufficient energy to overcome the potential of the double layer, and that only a single upstream plasma source is required to maintain this phenomenon. © 2007 American Institute of Physics. DOI: 10.1063/1.2803763 High energy charged particles in space are thought to be accelerated by mechanisms such as proposed by Fermi, by waves, and more recently, by electric double layers DLs. 1‐3 Although some experimental data obtained from probes on satellites are available, they are rarely sufficient to fully develop self-consistent models of such space DLs and assumptions on the form of the accelerated and trapped particle distribution functions have to be made. Perkins and Sun predicted the existence of current-free double layer solutions, 4 and soon after their prediction, current-driven laboratory double layers were set up in a current-free “mode,” 5‐7 confirming the prediction. More recently, a new class of currentfree double layers were experimentally found in expanding