It is shown that externally magnetized gas-puff z-pinches under compression can exhibit robust axial flux amplification under suitable axial boundary conditions. This effect relies upon the Hall term in the generalized Ohm's law to generate azimuthal currents in the presence of a driving axial electric field. Under dynamic compression, the total current tends to flow in a mostly force-free boundary layer, separating the predominately azimuthal field outside the layer and the predominately axial field inside the layer. The effect only appears to occur if the axial boundaries allow for outflow or absorption of electromagnetic energy. The effect is mitigated by imposing either periodic or conducting axial boundary conditions. A semi-analytic equilibrium analysis agrees with steady-state solutions of the time-dependent electron-magnetohydrodynamic equations and provides an estimate of the scaling of the boundary layer as well as suggesting a scenario for the formation of the boundary layer. When operative, the effect can significantly impede plasma compression due to the increase in axial flux that diffuses into the pre-compressed plasma or through the presence of conductors that inhibit movement of the generated axial flux. Several facilities have noted unusual implosion behavior in z-pinch experiments with applied axial fields that does not appear to be explainable within the standard magnetohydrodynamic model. It is suggested that these experiments can be explained by the axial flux amplification and concentration effect.

中文翻译：

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外部磁化 z 箍缩的霍尔磁流体动力学模拟中的轴向磁通放大

结果表明，在合适的轴向边界条件下，压缩下的外部磁化喷气 z 夹点可以表现出强大的轴向通量放大。这种效应依赖于广义欧姆定律中的霍尔项，以在存在驱动轴向电场的情况下产生方位角电流。在动态压缩下，总电流倾向于在几乎不受力的边界层中流动，将层外主要为方位角的场与层内以轴向场为主的场分开。只有当轴向边界允许电磁能流出或吸收时，才会出现这种效果。通过施加周期性或传导轴向边界条件来减轻这种影响。半解析平衡分析与瞬态电子-磁流体动力学方程的稳态解一致，并提供了对边界层缩放的估计，并提出了形成边界层的方案。当操作时，由于扩散到预压缩等离子体中的轴向通量的增加或通过抑制所产生的轴向通量的运动的导体的存在，该效应可显着阻碍等离子体压缩。一些设施已经注意到在使用轴向场的 z 夹点实验中不寻常的内爆行为，这在标准磁流体动力学模型中似乎无法解释。建议这些实验可以用轴向通量放大和集中效应来解释。