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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Evaluating the deHoffmann-Teller Cross-Shock Potential at Real Collisionless Shocks
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Evaluating the deHoffmann-Teller Cross-Shock Potential at Real Collisionless Shocks

机译：评估deHoffmann-Teller Cross-Shock在真正的无碰撞的潜在冲击

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摘要

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.
机译：冲击波是一种常见的在日球层超越。天体物理等离子体允许能量由冲击处理分区中粒子群体和电磁通过物理机制不能很好地领域理解。这种冲击是依赖于框架的。这一事件散装速度是平行磁场,deHoffmann-Teller框架,潜在的直接链接到两极电场建立的电子压力梯度。理解这种潜在的解决了电子分区问题,提供了一些见解竞争的冲击过程。以来电场在空间中是有问题的变化的测量可以抵消等离子体条件。可以大或比冲击的潜力。从美国宇航局和等离子体测量磁性层的多尺度任务尝试这个计算。deHoffmann-Teller框架转换包括时间的变化,得出结论实践这些固有面临困难3 d时间自然真实的冲击相比一维模拟。基于电子流体和动力学分析提供最强劲的措施deHoffmann-Teller潜力,但一些护理电场可以直接集成同意。很难独立评估的作用其他进程,如散射的冲击动荡,电子会计供暖。

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