The DC and radio frequency (RF) properties of RF driven sheaths were studied in the Large Plasma Device (LAPD) at the University of California, Los Angeles. The experiments diagnosed RF sheaths on field lines connected to a grounded plate at one end and an ion cyclotron range of frequencies antenna at the other end. The experimental setup permitted measurement of the RF sheath impedance at the plate as a function of DC sheath voltage, with the latter controlled by varying the RF current applied to the antenna. The DC–voltage characteristics of these sheaths and the RF sheath impedance measurements were compared with modeling. Hot electrons, present in the LAPD plasma, were inferred to contribute significantly to both the DC and RF currents and hence the RF impedance. It was postulated that at very low power, hot electrons could not access the region of the plasma subject to RF waves resulting in an increased RF impedance. Within some experimental limitations and significant assumptions, an RF sheath impedance model was verified by the experimental data.

中文翻译：

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大型磁化等离子体中射频鞘层阻抗的测量和建模

加利福尼亚大学洛杉矶分校的大型等离子体设备 (LAPD) 研究了射频驱动护套的直流和射频 (RF) 特性。实验诊断了场线上的射频护套，其一端连接到接地板，另一端连接到离子回旋加速器频率范围。实验设置允许测量板处的 RF 鞘阻抗作为 DC 鞘电压的函数，后者通过改变施加到天线的 RF 电流来控制。这些护套的直流电压特性和射频护套阻抗测量值与建模进行了比较。据推测，LAPD 等离子体中存在的热电子对 DC 和 RF 电流以及 RF 阻抗都有显着贡献。据推测，在非常低的功率下，热电子无法进入受射频波影响的等离子体区域，导致射频阻抗增加。在一些实验限制和重要假设内，RF 护套阻抗模型由实验数据验证。