In this study, a newly developed correction method with external magnetic measurements for the magnetohydrodynamics (MHD) simulation of the collisional merging formation of a field-reversed configuration (FRC) realized the estimation of the internal structure of the FRCs without invasive internal measurements. In the collisional merging formation of FRCs, an FRC is formed via merging of two initial FRC-like plasmoids at supersonic/Alfvénic velocity. An invasive diagnostic may also interfere with the collisional merging formation process. A two-dimensional resistive MHD simulation was conducted to evaluate the global behavior and internal structure of FRCs in the collisional merging formation process without invasive measurements. This code simulated the initial formation and collisional merging processes of FRCs including discharge circuits. However, the translation velocity and the pressure of initial FRCs did not simultaneously agree with the experimental values because the magnetic pressure gradient in each formation region could not be reproduced without the artificial adjustment of the initial condition. The experimentally measured current distribution was given as the initial condition of the circuit calculation in the developed correction method. The initial FRCs were successfully translated at the translation velocity and plasma pressure in the corrected simulation, both of which were equivalent to the experiments. The properties of the merged FRCs in the experiments such as volume, total temperature, and average electron density were reproduced in the corrected simulation. The detailed radial profile of the internal magnetic field of the FRC was also measured and found to agree very well with the simulation results.

中文翻译：

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通过非侵入性磁测量校正的超音速 FRC 合并的 MHD 模拟

在这项研究中，一种新开发的外部磁测量校正方法用于磁场反转配置（FRC）碰撞合并地层的磁流体动力学（MHD）模拟，实现了对 FRC 内部结构的估计，无需侵入性内部测量。在 FRC 的碰撞合并形成中，FRC 是通过以超音速/阿尔芬速度合并两个初始的 FRC 样等离子体团而形成的。侵入性诊断也可能干扰碰撞合并地层过程。进行了二维电阻 MHD 模拟，以评估 FRC 在碰撞合并形成过程中的全局行为和内部结构，无需侵入性测量。该代码模拟了包括放电电路在内的 FRC 的初始形成和碰撞合并过程。然而，初始FRCs的平移速度和压力与实验值并不一致，因为每个地层区域的磁压力梯度在没有初始条件的人工调整的情况下无法再现。在开发的校正方法中，实验测量的电流分布被作为电路计算的初始条件。初始 FRC 在校正模拟中的平移速度和等离子体压力下成功平移，两者均与实验等效。在校正后的模拟中重现了实验中合并 FRC 的特性，例如体积、总温度和平均电子密度。