Phase Diagram of Plasma Turbulence Structures

在九州大学LMD-U中对磁化等离子体的湍流结构进行了表征，并绘制了等离子体态相图。我们用多通道探针阵列观察了密度波动谱。在填充气体压力和磁场的扫描空间中发现了不同类型的光谱和分岔现象。进一步分析了分岔状态转换过程中的动力学特性。我们将光谱类型视为等离子体湍流特定状态的指标，并通过特征低频模式的幅度和总双相干来量化状态。本研究是非平衡系统相图展开的一个具体实例。

We characterized structures of turbulence in magnetized plasma for a wide range of operational parameters of magnetic field and filling gas pressure and made a phase diagram of plasma states in LMD-U at Kyushu University. We observed density fluctuation spectra with a multi-channel probe array. Different types of spectra and bifurcation phenomena were found in the scanned space of filling gas pressure and magnetic field. Furthermore, the dynamics during transitions between bifurcated states were analyzed. We considered the type of spectrum as an index of the specific state of plasma turbulence and quantified the state by amplitude and total bi-coherence of characteristic low frequency modes. This research is one concrete example of an expansion of the phase diagram in a non-equilibrium system.