通过一个系统发展的理论，我们证明了[Y. Z. Zhang，Z. Y. Liu，T. Xie，S. M. Mahajan和J. Liu，Physics of Plasmas 24，122304（2017）]与托卡马克中观察到的测地声学模式（GAM）的间歇性激发和传播高度相关。虽然许多数值模拟观察到的现象，这是第一个理论，揭示了GAM间歇性激发和传播背后的物理机制。前面的工作是基于与环形离子温度梯度（ITG）模式相关的微观湍流和基于板的带状流唯象模型。当系统中引入全环面效应时，出现了两个分支的纬向流：环面修正的低频纬向流（TLFZF）和GAM，这就需要对GAM和TLFZF进行统一的研究。事实上，我们观察到的过渡（衰变）从空穴到瞬子是由漂移波的径向群速度的快速过零触发，并被发现是强烈相关的GAM发病。因此，在数值实验中确定了在真实机器中观察到的间歇性GAM所特有的许多功能。结果将以图形和电影的形式显示;首先是单个中心有理曲面，然后是耦合的多个中心有理曲面。首先显示的周期性爆发消失，取而代之的是不规则的，更类似于GAM实验中观察到的间歇性特征。
英文摘要：
Through a systematically developed theory, we demonstrate that the motion of instanton identified in [Y. Z. Zhang, Z. Y. Liu, T. Xie, S. M. Mahajan, and J. Liu, Physics of Plasmas 24, 122304 (2017)] is highly correlated to the intermittent excitation and propagation of geodesic acoustic mode (GAM) that are observed in tokamaks. While many numerical simulations have observed the phenomena, it is the first theory that reveals the physical mechanism behind GAM intermittent excitation and propagation. The preceding work is based on the micro-turbulence associated with toroidal ion temperature gradient (ITG) mode, and slab-based phenomenological model of zonal flow. When full toroidal effect are introduced into the system, two branches of zonal flow emerge: the torus-modified low frequency zonal flow (TLFZF), and GAM, necessitating a unified exploration of GAM and TLFZF. Indeed, we observe that the transition (decay) from the caviton to instanton is triggered by a rapid zero-crossing of radial group velocity of drift wave and is found to be strongly correlated with the GAM onset. Many features peculiar to intermittent GAMs, observed in real machines, are thus identified in the numerical experiment. The results will be displayed in figures and in a movie; first for single central rational surface, and then with coupled multiple central rational surfaces. The periodic bursting first shown disappears as being replaced by irregular one, more similar to the intermittent characteristics observed in GAM experiments.
Improved n=1 Empirical Error Field Penetration Threshold Scaling with Ohmic and L-Mode Conventional Tokamak Plasma Discharges
Columbia University（哥伦比亚大学）；Seoul National University（首尔大学）；Institute of Plasma Physics Chinese Academy of Sciences（中国科学院等离子体物理研究所）；Huazhong University of Science and Technology（华中科技大学）；General Atomics（通用原子公司）；Consorzio RFX (CNR, ENEA, INFN, Universitá di Padova, Acciaierie Venete SpA)（RFX联合体（意大利国家研究委员会、国家新能源与可再生能源署、意大利国家核物理研究所、帕多瓦大学、威尼斯钢铁公司））；University of Padova（帕多瓦大学）；UKAEA, Culham Campus（英国原子能管理局，库姆校区）
The intermittent excitation of geodesic acoustic mode by nonlinear Instanton of electron drift wave envelope in L-mode discharge near tokamak edge
在纬向流存在下，漂移波包络的演化有两个不同的阶段。一个长寿命的驻波相，我们称之为Caviton，和一个短寿命的行波相（在径向方向），我们称之为Instanton。对于由离子温度梯度模式（ITG）驱动的漂移波湍流，这两个阶段的动力学在[Zhang Y Z，Liu Z Y，Xie T，Mahajan S M and Liu J 2017 Physics of Plasmas 24 122304]中显示。在本文中，我们证明了当湍流沿电子方向旋转时，ITG湍流的动力学性质很容易被复制;我们的模型计算特别处理了著名的δ_e模型中的环形电子漂移波（EDW）。虽然基本的计算是在平行的ITG对应，更多的重点放在这里的瞬时子的运动，在托卡马克中观察到的几个突然的现象，如间歇性激发的测地线声学模式（GAM）在本文中所示，可以归因于瞬时子的突然和快速的径向运动。计算得出了瞬子的定义特征：它在跃迁后立即开始为线性行波。然后，随着频率一直增加到20 kHz，它演变到非线性阶段。纬向流方程对雷诺应力的调制会引起GAM的共振激发。由于反应区中多个中心有理表面之间的随机相混合，显示了不连续性。
Transferable Cross-Tokamak Disruption Prediction with Deep Hybrid Neural Network Feature Extractor
Huazhong University of Science and Technology（华中科技大学）；Institute of Plasma Physics, HFIPS, Chinese Academy of Sciences（中国科学院合肥物质科学研究院等离子体物理研究所）；Shenzhen University（深圳大学）
Fusion power production in tokamaks uses discharge configurations that risk producing strong Type I Edge Localized Modes. The largest of these modes will likely increase impurities in the plasma and potentially damage plasma facing components such as the protective heat and waste divertor. Machine learning-based prediction and control may provide for online mitigation of these damaging modes before they grow too large to suppress. To that end, large labeled datasets are required for supervised training of machine learning models. We present an algorithm that achieves 97.7% precision when autom…
Reinforcement learning for vertical position control on the EXL-50U spherical tokamak
Beijing ENN Fusion Energy Science and Technology Co., Ltd.（北京恩诺聚变能源科技有限公司）；Beijing Key Laboratory of High Magnetic Field Spherical Torus Fusion Energy（北京市高磁场球形托卡马克聚变能重点实验室）；Hebei Key Laboratory of Compact Fusion（河北省紧凑型聚变重点实验室）；School of Nuclear Science and Engineering, East China University of Technology（华东理工大学核科学与技术学院）；Institute of Robotics and Automatic Information System, Nankai University（南开大学机器人与自动化信息系统研究所）；Key Laboratory of Materials Modification by Beams of the Ministry of Education, School of Physics, Dalian University of Technology（大连理工大学物理学院教育部 beam 材料改性重点实验室）；Dalian University of Technology（大连理工大学）
Several new results in the physics of edge poloidal flows, turbulent stresses and momentum transport are reported. These are based on experiments on the HL-2A tokamak. Significant deviation from neoclassical prediction for mean poloidal flow in Ohmic and L mode discharges is deduced from direct measurements of the turbulent Reynolds stress. The deviation increases with heating power. The turbulent poloidal viscosity is synthesized from fluctuation data, and is found to be comparable to the turbulent particle diffusivity. The intrinsic poloidal torque is deduced from synthesis, for the first ti…
En route to realistic modeling of the kinetic-MHD interaction between macroscopic modes and fast particles induced by neutral beam injection in tokamaks
The tearing mode, a large-scale MHD instability in tokamak, typically disrupts the equilibrium magnetic surfaces, leads to the formation of magnetic islands, and reduces core electron temperature and density, thus resulting in significant energy losses and may even cause discharge termination. This process is unacceptable for ITER. Therefore, the accurate identification of a magnetic island in real time is crucial for the effective control of the tearing mode in ITER in the future. In this study, based on the characteristics induced by tearing modes, an attention-aware convolutional neural net…
The Negative Triangularity Tokamak Path for Fusion Pilot Plants: Experimental Progress and Future Prospects
General Atomics（通用原子能公司）；Institute for Fusion Studies, University of Texas – Austin（德克萨斯大学奥斯汀分校聚变研究所）；Ecole Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；University of California, San Diego（加州大学圣地亚哥分校）；Columbia University（哥伦比亚大学）；Lawrence Livermore National Laboratory（劳伦斯利弗莫尔国家实验室）；Plasma Science and Fusion Center, MIT（麻省理工学院等离子体科学与聚变中心）
The dynamic interplay between the core and the edge plasma has important consequences in the confinement and heating of fusion plasma. The transport of the Scrape-Off-Layer (SOL) plasma imposes boundary conditions on the core plasma, and neutral transport through the SOL influences the core plasma sourcing. In order to better study these effects in a self-consistent, time-dependent fashion with reasonable turn-around time, a reduced model is needed. In this paper we introduce the SOL Box Model, a reduced SOL model that calculates the plasma temperature and density in the SOL given the core-to-…
Demonstration of H-mode Error Field Identification in a Single Discharge via Island Healing
Columbia University（哥伦比亚大学）；Columbia Fusion Research Center（哥伦比亚聚变研究中心）；General Atomics（通用原子能公司）；Princeton Plasma Physics Laboratory（普林斯顿等离子体物理实验室）；Korea Institute of Fusion Energy（韩国聚变能源研究所）
Poloidal inhomogeneity of the particle fluctuation induced fluxes near of the LCFS at lower hybrid heating and improved confinement transition at the FT-2 tokamak
