Filament size of floating-emissive probe for low density plasmas with large space potential
Filament size of floating-emissive probe for low density plasmas with large space potential
复制标题
大空间势低密度等离子体浮动发射探针灯丝尺寸
DOI：
10.1063/1.1619549
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发表时间：
2003
影响因子：
1.6
通讯作者：
Z. Yoshida
中科院分区：
文献类型：
--
作者：
H. Himura;M. Fukao;H. Wakabayashi;Z. Yoshida
通过两个浮动发射探针测量低密度 ne∼1012 m−3 非中性等离子体的空间势 φs。除了细丝的面积S之外，它们之间没有任何不同。尽管热电子电流已充分发射，但在某些测量点，较小灯丝输出的浮动电势 φf 远大于实际的 φs，这与探针测量中广为人知的 φf⩽φs 关系相反。该结果归因于在具有大的 φs 的低 Ne 等离子体中收集的探针电流 Ip 不足。这是因为，在这样的等离子体中，尽管浮置发射法所需的Ip值很小，但Ip并不总是满足Ip>φs/RHI的必要条件，其中RHI是高阻抗电阻。为了正确确定等离子体的 φs，S 必须大于 φs/ene<ve>RHI，其中 e 是电子电荷，<ve> 是收集到探针的电子的平均速度。
Space potential φs of non-neutral plasmas with a low density of ne∼1012 m−3 are measured by two floating-emissive probes. Nothing is different between them except the area S of filaments. Despite the fact that the thermionic current is sufficiently emitted, floating potential φf outputted from the smaller filament is much larger than the realistic φs at some measurement points, which is contrary to the widely known relation of φf⩽φs in probe measurements. The result is attributed to the insufficient probe current Ip collected in low-ne plasmas with a large φs. This is because, in such a plasma, Ip does not always satisfy the necessary condition of Ip>φs/RHI, where RHI is a high impedance resistor, although the value of Ip required for the floating emissive method is very small. In order to correctly determine the φs of the plasmas, S must be larger than φs/ene〈ve〉RHI, where e is the electron charge and 〈ve〉 is the mean speed of electrons collected to the probe.