Investigation of the Characteristics of String-Plasma

我们在弦等离子体的两年研究计划中的成果总结如下。利用TP-D型放电装置，建立了一种新型的稳态等离子体（或“弦线等离子体”）产生技术。在该等离子体中，大多数离子引导中心被放置在等离子体柱的轴附近。为了达到这种情况，采用了以下两种方法：（1）径向直流电场内产生的圆柱形浮动电极与一个非常小的内径和（2）尖点磁场配置.对弦等离子体的详细测量揭示了这种等离子体的几个特征：（1）柱半径等于或小于离子的拉莫尔半径。(2)大部分低导中心位于等离子体柱的轴附近，那么，等离子体作为一个整体似乎是抗磁性旋转的。(3)等离子体空间电势的分布在径向方向上具有陡峭的梯度;因此，强径向直流电场存在于等离子体中。(4)尽管弦等离子体具有上述特性，但它总体上是电中性的.利用弦等离子体的上述特性，提出了如下应用：（1）利用离子回旋共振技术产生无杂质的低能离子束或流，分离不同质量的离子;（2）利用弦等离子体的有效反磁效应产生高β稳态等离子体。

Achievements of our two-year research project on string-plasma are summarized below.1. A technique to produce a new type of filamentary plasma (or "string-plasma") in steady-state has been established by utilizing a TP-D type discharge apparatus. In this plasma, the majority of ion guiding centers are placed in the vicinity of the axis of the plasma column. In order to attain this situation, the following two methods were employed utilizing :(1) Radial dc-electric fields generated inside cylindrical floating electrodes with an extremely small inner diameterand(2) A point-cusp magnetic-field configuration.2. Detailed measurements of string-plasma revealed several characteristics of this plasma :(1) The column radius is equal to or less than the ion Larmor radius.(2) The majority of iow guiding centers lie in the vicinity of the axis of the plasma column ; then, the plasma as a whole appears to rotate diamagnetically.(3) The profile of the plasma space potential has a steep gradient in the radial direction ; as a result, strong radial dc-electric fields exist across plasma.(4) In spite of the above peculiar characteristics, string-plasma as a whole is electrically neutral.3. Applications that utilize the above special characteristics of string-plasma such as the following have been proposed :(1) Production of impurity-free, low-energy ion-beam or stream applying ion-cyclotron resonance technique to this plasma to separate different mass ion speciesand(2) Production of high-beta steady-state plasma using the efficient diamagnetic effect of string-plasmaSome experiments and computer simulations have been carried out in order to verify the usefulness of these applications.