Shock waves are common in the heliosphere and beyond. The collisionless nature of most astrophysical plasmas allows for the energy processed by shocks to be partitioned amongst particle sub-populations and electromagnetic fields via physical mechanisms that are not well understood. The electrostatic potential across such shocks is frame dependent. In a frame where the incident bulk velocity is parallel to the magnetic field, the deHoffmann-Teller frame, the potential is linked directly to the ambipolar electric field established by the electron pressure gradient. Thus measuring and understanding this potential solves the electron partition problem, and gives insight into other competing shock processes. Integrating measured electric fields in space is problematic since the measurements can have offsets that change with plasma conditions. The offsets, once integrated, can be as large or larger than the shock potential. Here we exploit the high-quality field and plasma measurements from NASA's Magnetospheric Multiscale mission to attempt this calculation. We investigate recent adaptations of the deHoffmann-Teller frame transformation to include time variability, and conclude that in practice these face difficulties inherent in the 3D time-dependent nature of real shocks by comparison to 1D simulations. Potential estimates based on electron fluid and kinetic analyses provide the most robust measures of the deHoffmann-Teller potential, but with some care direct integration of the electric fields can be made to agree. These results suggest that it will be difficult to independently assess the role of other processes, such as scattering by shock turbulence, in accounting for the electron heating.

中文翻译：

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评估真实无碰撞冲击下的 deHoffmann-Teller 交叉冲击潜力

冲击波在日光层及其他地方很常见。大多数天体物理等离子体的无碰撞特性允许通过尚未完全了解的物理机制将冲击处理的能量分配到粒子亚群和电磁场中。这种冲击的静电势取决于框架。在入射体积速度平行于磁场的坐标系中，德霍夫曼-泰勒坐标系，电位直接与由电子压力梯度建立的双极电场相关联。因此，测量和理解这种潜力解决了电子分配问题，并深入了解其他竞争性冲击过程。在空间中集成测量的电场是有问题的，因为测量可能具有随等离子体条件变化的偏移。偏移量一旦被整合，就可能与冲击潜力一样大或更大。在这里，我们利用来自 NASA 磁层多尺度任务的高质量场和等离子体测量来尝试这种计算。我们调查了 deHoffmann-Teller 框架变换的最新适应，以包括时间可变性，并得出结论，与 1D 模拟相比，这些在实践中面临着真实冲击的 3D 时间相关性质所固有的困难。基于电子流体和动力学分析的电位估计提供了最可靠的 deHoffmann-Teller 电位测量值，但如果小心谨慎，可以使电场的直接积分达成一致。这些结果表明，很难独立评估其他过程的作用，例如激波湍流的散射、