Using multipoint Magnetospheric Multiscale (MMS) observations in an unusual string-of-pearls configuration, we examine in detail observations of the reformation of a fast magnetosonic shock observed on the upstream edge of a foreshock transient structure upstream of Earth's bow shock. The four MMS spacecraft were separated by several hundred kilometers, comparable to suprathermal ion gyroradius scales or several ion inertial lengths. At least half of the shock reformation cycle was observed, with a new shock ramp rising up out of the “foot” region of the original shock ramp. Using the multipoint observations, we convert the observed time-series data into distance along the shock normal in the shock's rest frame. That conversion allows for a unique study of the relative spatial scales of the shock's various features, including the shock's growth rate, and how they evolve during the reformation cycle. Analysis indicates that the growth rate increases during reformation, electron-scale physics play an important role in the shock reformation, and energy conversion processes also undergo the same cyclical periodicity as reformation. Strong, thin electron-kinetic-scale current sheets and large-amplitude electrostatic and electromagnetic waves are reported. Results highlight the critical cross-scale coupling between electron-kinetic- and ion-kinetic-scale processes and details of the nature of nonstationarity, shock-front reformation at collisionless, fast magnetosonic shocks.

在不寻常的珍珠串配置中使用多点磁层多尺度 (MMS) 观测，我们详细检查了在地球弓形激波上游的前震瞬态结构的上游边缘观察到的快速磁声波的重组的详细观测。四个 MMS 航天器相距数百公里，相当于超热离子回旋半径尺度或几个离子惯性长度。至少观察到一半的激波重整周期，新激波斜坡从原始激波斜坡的“脚”区域上升。使用多点观测，我们将观测到的时间序列数据转换为沿激波静止帧中激波法线的距离。这种转换允许对冲击各种特征的相对空间尺度进行独特的研究，包括冲击的增长率，以及它们在改革周期中如何演变。分析表明，重整过程中增长率增加，电子尺度物理在激波重整中起重要作用，能量转换过程也与重整过程具有相同的周期性。据报道，强、薄的电子动力学电流片和大振幅静电波和电磁波。结果突出了电子动力学和离子动力学尺度过程之间的关键跨尺度耦合，以及在无碰撞、快速磁声激波中非平稳性、激波前重组的性质的细节。电子尺度物理在激波重整中发挥着重要作用，能量转换过程也经历与重整相同的循环周期。据报道，强、薄的电子动力学电流片和大振幅静电波和电磁波。结果突出了电子动力学和离子动力学尺度过程之间的关键跨尺度耦合，以及在无碰撞、快速磁声激波中非平稳性、激波前重组的性质的细节。电子尺度物理在激波重整中发挥着重要作用，能量转换过程也经历与重整相同的循环周期。据报道，强、薄的电子动力学电流片和大振幅静电波和电磁波。结果突出了电子动力学和离子动力学尺度过程之间的关键跨尺度耦合，以及在无碰撞、快速磁声激波中非平稳性、激波前重组的性质的细节。