Structural Model Analysis of Bistable Magnetized Plasma and Study on Dynamic Control

在本研究中，我们旨在澄清磁化等离子体中尚未探索的跃迁现象的机制，建立一个新的模型，并试图在此基础上控制跃迁行为。我们控制了密度分布和剪切流，并通过静态和主动偏压的方法，研究了浸没在直径为45 cm的rf磁化等离子体中的10个同心圆的自激双稳态密度跃迁现象。利用研制的24通道探头和记录仪系统（40ch, 50 ns， 10 μs采样次数，12-16位）测量了详细的时空结构。在整体密度跃迁的同时，在全局范围内观察到电位跃迁现象，偏置电流的变化时间（低至1 ~ 2 μs）比密度的变化时间（<1 ms）短，电位的变化时间较慢（1 ~ 10 μ ms）。观测区域之间的时间差异也被观察到。有几个过渡步骤，第一个在1 ~ 10 μs量级。从这些结果中发现，电极区域附近的变化对于触发过渡是重要的。模拟结果也支持这些现象（离子聚集运动的重要性）。此外，停留时间概率和平均停留时间对偏置电压存在滞回（不是直流滞回，而是随机滞回），这些也可以从密度和浮动电位的分布中观察到。这些结果还表明，精细空间结构的重要性和电极附近区域的作用是非常有趣的特征。

In this study, we aimed at establishing a new model after clarifying the mechanism of transition phenomena, which have not been explored, in magnetized plasmas, and tried to control the transition behavior based on this understanding.We controlled the density distribution and the sheared flow, and the investigated the self-excited, bistable density transition phenomena, by biasing voltage statically and actively to the ten concentric rings immersed into a rf produced, magnetized plasma with a large diameter of 45 cm. Detailed spatio-temporal structures were measured by developed 24-channel probes and logger system (40 ch. with 50 ns and 10 μs sampling times and 12-16 bits). Potential transition phenomena were observed globally at the same time of global density transition Changing time of the bias current (down to 1-2 μs) was shorter than that of the density (<1 ms), and that of the potential was slow (>1 ms). Differences of this time between observed regions were also observed. There were a few steps of transitions, and the first one was on the order of 1-10 μs. From these results, it was found that the change near the electrode region was important to trigger the transition. Simulation results also support these phenomena (importance of the ion bunching motion).Furthermore, there were hystereses of the staying time probability and average staying time as to the biased voltage (not dc hestereses but stochastic sense of ones), and these were also observed from distributions of density and floating potential. From these results, it was also suggested that the importances of fine spatial structures and the role of the region near the electrode, which are very interesting features.