Field-aligned Boltzmann electric triple layer in a low-pressure expanding plasma
Field-aligned Boltzmann electric triple layer in a low-pressure expanding plasma
复制标题
低压膨胀等离子体中的场对准玻尔兹曼电三层
DOI：
10.1088/1361-6595/ab20a5
复制
发表时间：
2019
影响因子：
3.8
通讯作者：
R. Boswell
中科院分区：
文献类型：
--
作者：
A. Bennet;C. Charles;R. Boswell
在膨胀等离子体装置的源管出口处，沿沿着最后一条磁力线测量了一个深而窄的势结构。电势结构被确定为电三层，其特征在于具有全宽半最大值为170德拜长度（16 mm），深度为125 V（q drop / kT e 2）的电势凹陷，并且可以看到其宽度和幅度随着氩气压力的增加而减小。三层作为场对准电子传输的势垒，在重新加速进入膨胀室之前使离开等离子体源的热电子减速，这些热电子能够克服三层电势，解释了先前发表的高密度等离子体圆锥的形貌。在位置的上游和下游的潜在结构的电子能量概率函数的测量显示两个温度的电子种群的断裂能量分别为41.5 V和22 V，值是一致的等离子体电位测量沿着的场线。在这些实验条件下，源管的电介质壁的电荷显着负电位和接近的场线，这个带负电荷的壁似乎是三层的原因。
A deep and narrow potential structure has been measured along the last magnetic field line to exit the source tube of an expanding plasma device. The potential structure is identified as an electric triple layer and features a potential dip with Full Width Half Maximum ∼70 Debye lengths (16 mm), depth of ∼25 V ( q ϕ drop / kT e ∼ 2 ) and its width and magnitude are seen to decrease with increases in argon pressure. The triple layer acts as a potential barrier for field-aligned electron transport, decelerating hot electrons exiting the plasma source before reaccelerating into the expansion chamber those that are able to overcome the triple layer potential, explaining the topography of high density plasma conics published previously. Measurements of the electron energy probability function at locations upstream and downstream of the potential structure show two-temperature electron populations with break energies of 41.5 V and 22 V, respectively, values that are consistent with the plasma potential measurements along the field line. Under these experimental conditions, the dielectric wall of the source tube charges to significantly negative potentials and the proximity of the field line to this negatively charged wall appears to be the cause for the triple layer.