Selective radial release of hot, magnetised electrons downstream of a low-pressure expanding plasma
Selective radial release of hot, magnetised electrons downstream of a low-pressure expanding plasma
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低压膨胀等离子体下游的热磁化电子的选择性径向释放
DOI：
10.1088/1361-6463/aad74f
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
R. Boswell
中科院分区：
文献类型：
--
作者：
A. Bennet;C. Charles;R. Boswell
深入了解不同几何和磁场配置下膨胀等离子体装置中的粒子输运，对于未来的推力器和反应堆设计是必要的。最近，我们已经表明，通过热电子传输沿着最径向的场线逃逸的扩展等离子体装置的源区的高密度二次曲线的发展是至关重要的轴上的高速离子束的发展。在这项研究中，源区域和可移动的延伸管插入在下游的膨胀等离子体装置之间的间隙被用来创建一个几何窗口的可变大小。只有那些位于穿过这个窗口的场线上的电子布居才能被传输到通常形成高密度圆锥的区域。等离子体行为的临界场线确定通过增加几何窗口的大小，同时测量的圆锥曲线密度和离子束特性。当高密度二次曲线能够完全改革时，观察到束流速度的阶跃变化。负责完整的二次曲线形成的场线被发现是那些通过在1002集肤深度的源室壁。因此，下游等离子体行为由位于场线上的电子主导，这些电子最有效地被射频天线加热并逃离源。
A thorough understanding of particle transport in expanding plasma devices under different geometric and magnetic configurations is necessary for future thruster and reactor design. Recently, we have shown that the development of high density conics via hot electron transport along the most radial field lines escaping the source region of an expanding plasma device is crucial for the development of a high velocity ion beam on axis. In this study, a gap between the source region and a movable extension tube inserted in the downstream of an expanding plasma device is used to create a geometric window of variable size. Only those electron populations situated on field lines that pass through this window can be transported to the region where high density conics normally form. Critical field lines for the plasma behaviour are identified by increasing the size of the geometric window while concurrently measuring the conics density and ion beam characteristics. A step change in the beam velocity is observed when high density conics are able to fully reform. The field lines responsible for full conics formation are found to be those that pass within ∼2 skin depths of the source chamber wall. As such, the downstream plasma behaviour is dominated by electrons situated on field lines that are most effectively heated by the radio-frequency antenna and escape the source.