At the high $n_{e}$ proposed for high-field fusion reactors, it is uncertain whether ionization, as opposed to plasma transport, will be most influential in determining $n_{e}$ at the pedestal and separatrix. A database of Alcator C-Mod discharges is analyzed to evaluate the impact of source modification via cryopumping. The database contains similarly-shaped H-modes at fixed $I_{p} =$ 0.8 MA and $B_{t} =$ 5.4 T, spanning a large range in $P_\mathrm{net}$ and ionization. Measurements from an edge Thomson Scattering system are combined with those from a midplane-viewing Ly$_α$ camera to evaluate changes to $n_{e}$ and $T_{e}$ in response to changes to ionization rates, $S_\mathrm{ion}$. $n_{e}^\mathrm{sep}$ and $T_{e}^\mathrm{ped}$ are found to be most sensitive to changes to $S_\mathrm{ion}^\mathrm{sep}$, as opposed to $n_{e}^\mathrm{ped}$ and $T_{e}^\mathrm{sep}$. Dimensionless quantities, namely $α_\mathrm{MHD}$ and $ν^{*}$, are found to regulate attainable pedestal values. Select discharges at different values of $P_\mathrm{net}$ and in different pumping configurations are analyzed further using SOLPS-ITER. It is determined that changes to plasma transport coefficients are required to self-consistently model both plasma and neutral edge dynamics. Pumping is found to modify the poloidal distribution of atomic neutral density, $n_{0}$, along the separatrix, increasing $n_{0}$ at the active X-point. Opaqueness to neutrals from high $n_{e}$ in the divertor is found to play a role in mediating neutral penetration lengths and hence, the poloidal distribution of neutrals along the separatrix. Pumped discharges thus require a larger particle diffusion coefficient than that inferred purely from 1D experimental profiles at the outer midplane.
Experimental Evidence for Increased Particle Fluxes Due to a Change in Transport at the Separatrix near Density Limits on Alcator C-Mod
MIT Plasma Science and Fusion Center（麻省理工学院等离子体科学与聚变中心）；Commonwealth Fusion Systems（联邦聚变系统）；University of California, San Diego（加利福尼亚大学圣迭戈分校）；Institute of Physics, University of Greifswald（格赖夫斯瓦尔德大学物理研究所）
DEGAS 2 model validation study: comparison of measured and modeled helium and deuterium line emission arising from an external gas puff on Alcator C-Mod
Deep electric field predictions by drift-reduced Braginskii theory with plasma-neutral interactions based upon experimental images of boundary turbulence
École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；Massachusetts Institute of Technology（麻省理工学院）
我们通过物理学深度学习提出了二维湍流电场计算，该计算符合（i）在具有纯环向场的轴对称聚变等离子体框架下的漂移减少的Braginskii理论，以及（ii）通过分析Alcator C-Mod托卡马克上放电的喷气成像获得的开放场线上波动电子密度和温度的实验估计。在简化的等离子体湍流模型中，考虑了局部膨胀的氦原子对粒子和能量的影响，增强了电场和电子压力之间的相关性。中性粒子还与加宽湍流场振幅分布和增加${\bf E \times B}$剪切速率直接相关。这表明了一种新的方法，在等离子体实验中，通过求解非线性动力学与偏微分方程和数据不编码显式边界或初始条件一致。
A predictive formula for the H-mode electron separatrix density: Bridging regression and physics-based models across C-Mod, AUG and JET tokamaks
Max-Planck-Institut für Plasmaphysik（马克斯·普朗克等离子体物理研究所）；Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA)（RFX联盟（国家研究委员会、意大利国家新能源研究中心、意大利国家核物理研究所、帕多瓦大学、威尼斯钢铁公司））；MIT Plasma Science and Fusion Center（麻省理工学院等离子体科学与聚变中心）；Oak Ridge National Laboratory（橡树岭国家实验室）；DTT S.c. a r.l.（DTT有限责任公司）；IRFM, CEA（法国原子能和替代能源署核聚变研究设施）；KU Leuven（荷语鲁汶大学）；KTH Royal Institute of Technology（瑞典皇家理工学院）；UKAEA（英国原子能管理局）；VTT（芬兰技术研究中心）
Physics-informed machine learning techniques for edge plasma turbulence modelling in computational theory and experiment
Western University（西安大略大学）；MIT Plasma Science and Fusion Center（麻省理工学院等离子体科学与聚变中心）
边缘等离子体湍流对磁约束聚变装置的性能至关重要。为了更好地理解理论和实验中的边缘湍流，开发了一个受偏微分方程约束的定制物理学深度学习框架，以准确地从电子压力的部分观测中学习与双流体理论一致的湍流场。这种计算是不可能的，否则使用传统的平衡模型。有了这种技术，第一个直接的定量比较静电双流体理论和电磁gyrokinetic模型之间的湍流场表现出良好的整体协议，发现在磁化螺旋等离子体在低归一化压力。为了将这些计算技术转化为实验聚变等离子体，通过一个新创建的深度学习框架展示了一种将HeI线辐射的亮度测量转化为局部等离子体波动的新方法，该框架集成了中性输运物理和碰撞辐射理论，用于氦原子中的$3^3 D - 2^3 P$跃迁。本论文利用Alcator C-Mod托卡马克装置上的快速相机数据，首次利用单根谱线对聚变等离子体中湍流电子密度、电子温度和中性密度进行了二维时间相关的实验测量。利用实验推断的数据，计算了轴对称聚变等离子体纯环向场框架下符合漂移简化Braginskii理论的二维湍流电场的初始估计值.发现氦原子对粒子和能量源的影响增强了电场和电子压力之间的相关性，同时加宽了影响${\bf E \times B}$流动和剪切速率的湍流场幅度。
