Space Charge in Ionization Detectors
Space Charge in Ionization Detectors
复制标题
电离探测器中的空间电荷
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
K. McDonald
中科院分区：
文献类型：
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作者：
Sandro Palestini;K. McDonald
Child [1]和Langmuir [2]首先考虑了自由电子空间变化分布（通常称为空间电荷）对真空二极管工作的影响。在该示例中，电子以低速从热阴极释放，然后在由漂移电子修改的局部电场的影响下自由漂移。在这个问题中，推导出电离检测器（其标称场E0 x在检测器的长度D上是均匀的）中受正离子空间电荷密度ρ（x）影响的稳态电场分布E = E（x）x。假设电离在整个探测器的体积中均匀地产生（通过宇宙射线或来自粒子加速器的次级粒子），体积速率为K个离子对/体积/秒。电离电子在阳极处被迅速收集，并且可以忽略相关的电子空间电荷密度。也就是说，你可以假设正离子的空间电荷密度不会大到阻止电离电子到达阳极。正离子以下式给出的速度缓慢地漂移到阴极：
The effect on the operation of a vacuum diode of a spatially varying distribution of free electrons, commonly called space charge, was first considered by Child [1] and Langmuir [2]. In that example electrons are released from a hot cathode at low velocity, and then drift freely under the influence of the local electric field as modified by the drifting electrons. In this problem, deduce the steady-state electric field distribution E = E(x) x in an ionization detector (whose nominal field, E0 x, is uniform over the length D of the detector) as affected by the positive-ion space-charge density ρ(x). Suppose that ionization is created uniformly throughout the volume of the detector (by cosmic rays or by secondary particles from a particle accelerator) at a volume rate of K ion pairs/volume/sec. The ionization electrons are quickly collected at the anode and the associated electron space-charge density can be ignored. That is, you may assume the positive-ion space-charge density is not so great as to prevent the ionization electrons from reaching the anode. The positive ions drift slowly to the cathode with a velocity given by