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

在本研究中，我们的目的是在弄清磁化等离子体中尚未被研究的跃迁现象的机制后，建立一个新的模型，并试图在此基础上控制跃迁行为。我们通过对浸入45 cm大直径射频产生的磁化等离子体中的10个同心圆环施加静态和主动的偏置电压来控制密度分布和剪切流动，并研究了自激双稳态密度跃迁现象。用研制的24道探头和记录仪系统(40ch)测量了详细的时空结构。50 ns，10μ，S采样次数，12-16比特)。在全局密度跃迁的同时，整体观察到了电势跃迁现象，偏流(低至1-2μS)比密度(~lt；1ms)的变化时间短，而电势的变化(~gt；1ms)较慢。还观察到了观测区域之间这一时间的差异。有几个跃迁步骤，第一个步骤约为1-10μ的S，从这些结果可以看出，电极区附近的变化是触发跃迁的重要因素。模拟结果也支持这些现象(离子聚束运动的重要性)。此外，驻留时间概率和平均驻留时间对偏置电压存在滞后(不是直流电效应，而是其随机性)，这也从密度和浮动势的分布中观察到。从这些结果还表明，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.