Rotating spokes commonly occur in partially magnetized plasmas devices. In this paper, the driving mechanism behind the formation of an m=1 rotating spoke mode in a magnetically enhanced hollow cathode arc discharge is investigated by means of 2D radial-azimuthal particle-in-cell/Monte Carlo collision simulations with a uniform axial magnetic field. We find that the formation of the spoke potential hump region can be explained as a result of the positive anode sheath collapse due to the lower hybrid type instability evolving into the long wavelength regime. It is shown that an initial short-wavelength instability in the non-neutral anode sheath undergoes a sequence of transitions into the large scale modes. The sheath non-neutrality effect on the instability is considered and incorporated in the two-fluid linear theory of the lower hybrid instability. The unstable modes predicted by the theory in the linear phase and nonlinear evolution are in good agreement with the fluctuation modes developed in the particle simulations.
Counter-rotating density and current structures in a partially magnetized $\mathbf{E}\times\mathbf{B}$ plasma
Huazhong University of Science and Technology（华中科技大学）；Wuhan University of Technology（武汉理工大学）；Anshan Normal University（鞍山师范学院）；Université de Toulouse, CNRS, INPT, UPS（图卢兹大学，法国国家科学研究中心，国立理工学院，联合物理研究所）
A phenomenological model for the description of rotating spokes in HiPIMS discharges
在圆形平面磁控管上方的电离区域中，观察到高发射率的良好定义的区域，当放电驱动在HiPIMS制度。一旦它们的模式稳定下来，这些结构就以数百kHz范围内的恒定旋转频率在E x B方向上旋转。的现象的唯象模型的发展，在一个系统的非线性耦合偏微分方程的形式。该系统在与结构共同运动的坐标系中解析求解，其解给出了中性密度和施加电子密度形状后的等离子体密度。从电离、电子损失和中性粒子不断填充机制的平衡出发，在旋转坐标系中得到了电子和中性粒子密度的稳态组态。因此，实验观察到的辐条可以简单地通过这种高度减少的现象数量的组合来维持。最后，研究了中性粒子和等离子体密度对物理参数的敏感性。
Benchmark for two-dimensional large scale coherent structures in partially magnetized ExB plasmas -- Community collaboration & lessons learned
Princeton Plasma Physics Laboratory（普林斯顿等离子体物理实验室）；Universidad Carlos III de Madrid（马德里卡洛斯三世大学）；Sandia National Laboratories（桑迪亚国家实验室）；CERFACS（欧洲流体力学计算中心）；Nuclear (NUC) Department, ENEA C.R. Frascati（意大利国家新能源与可再生能源署弗拉斯卡蒂研究中心核能部）；Stanford University（斯坦福大学）；HUN-REN Wigner Research Centre for Physics（匈牙利研究网络维格纳物理研究中心）；Ruhr University Bochum（波鸿鲁尔大学）；Imperial College London（伦敦帝国理工学院）；von Karman Institute for Fluid Dynamics（冯·卡门流体力学研究所）；KU Leuven（荷语鲁汶大学）；Institute for Plasma Science and Technology (ISTP), CNR（意大利国家研究委员会等离子体科学与技术研究所）；University of Saskatchewan（萨斯喀彻温大学）；University of Alberta（阿尔伯塔大学）；Dublin City University（都柏林城市大学）
