Topological configurations of the magnetic field play key roles in the dynamics of space plasmas. This study presents a novel algorithm that can estimate the quadratic magnetic gradient as well as the complete geometrical features of magnetic field lines, based on magnetic field and current density measurements by a multiple spacecraft constellation at four or more points. The explicit estimators for the linear and quadratic gradients, the apparent velocity of the magnetic structure and the curvature and torsion of the magnetic field lines can be obtained with well‐predicted accuracies. The feasibility and accuracy of the method have been verified with two demonstrations. The algorithm has been successfully applied to exhibit the geometrical structure of a flux rope. This algorithm has wide applications for studying a variety of magnetic configurations in space plasmas.

Shock ripples and shock–discontinuity interactions (SDIs) have long been proposed to explain the frequent occurrence of high‐speed jets (HSJs) in the magnetosheath; however, there is no direct observational evidence for either of them occurring near a shock. Herein, we report a large‐scale, long‐duration undulated quasi‐perpendicular shock surface that is capable of generating HSJs. Based on the curvatures estimated for the shock undulation and for a nearby hot flow anomaly (HFA), we suggest that the shock ripple mechanism and the SDI mechanism combine to generate HSJs, that is, during an SDI, shock undulations and an upstream HFA form simultaneously, and the solar wind between them is deflected by the undulation into jets. The HSJs, discontinuity, and HFA are then convected downstream. An HSJ consistent with our mechanism in another event is presented.

A novel algorithm for estimating both the linear and quadratic gradients of physical quantities based on multiple spacecraft observations using the least squares method is put forward. Using 10 or more spacecraft constellation measurements as input, this new algorithm can yield both the linear and quadratic gradients at the barycenter of the constellation. Iterations were used in the algorithm. Tests on cylindrical flux ropes, dipole magnetic field, and modeled geomagnetospheric field were carried out. The results of these tests indicate that the linear gradient obtained is of second‐order accuracy, while the quadratic gradient is of first‐order accuracy. The test on the modeled geomagnetospheric field showed that, the greater the number of spacecraft in the constellation, the greater the accuracy of the quadratic gradient calculated. However, the accuracy of the linear gradient obtained was independent of the number of spacecraft. The feasibility, reliability, and accuracy of this algorithm have been successfully verified. This algorithm could find wide applications in the design of future multiple spacecraft missions as well as in the analysis of multiple‐point measurement data.

Space plasmas are composed of charged particles that play a key role in electromagnetic dynamics. However, to date, there has been no direct measurement of the distribution of such charges in space. In this study, three schemes for measuring charge densities in space are presented. The first scheme is based on electric field measurements by multiple spacecraft. This method is applied to deduce the charge density distribution within Earth's magnetopause boundary layer using Magnetospheric MultiScale constellation (MMS) four‐point measurements, and indicates the existence of a charge separation there. The second and third schemes proposed are both based on electric potential measurements from multiple electric probes. The second scheme, which requires 10 or more electric potential probes, can yield the net charge density to first‐order accuracy, while the third scheme, which makes use of seven to eight specifically distributed probes, can give the net charge density with second‐order accuracy. The feasibility, reliability, and accuracy of these three schemes are successfully verified for a charged‐ball model. These charge density measurement schemes could potentially be applied in both space exploration and ground‐based laboratory experiments.

The study of jets in the Earth’s magnetosheath has been a subject of extensive investigation for over a decade due to their profound impact on the geomagnetic environment and their close connection with shock dynamics. While the variability of the solar wind and its interaction with Earth’s magnetosphere provide valuable insights into jets across a range of parameters, a broader parameter space can be explored by examining the magnetosheath of other planets. Here we report the existence of anti-sunward and sunward jets in the Jovian magnetosheath and show their close association with magnetic discontinuities. The anti-sunward jets are possibly generated by a shock–discontinuity interaction. Finally, through a comparative analysis of jets observed at Earth, Mars, and Jupiter, we show that the size of jets scales with the size of bow shock.

Shock-generated transients, such as hot flow anomalies (HFAs), upstream of planetary bow shocks, play a critical role in electron acceleration. Using multimission data from NASA’s Magnetospheric Multiscale and ESA’s Cluster missions, we demonstrate the transmission of HFAs through Earth’s quasi-parallel bow shock, accelerating electrons to relativistic energies in the process. Energetic electrons initially accelerated upstream are shown to remain broadly confined within the transmitted transient structures downstream, where they get further energized due to the elevated compression levels potentially by betatron acceleration. Additionally, high-speed jets form at the compressive edges of HFAs, exhibiting a significant increase in dynamic pressure and potentially contributing to further localized compression. Our findings emphasize the efficiency of quasi-parallel shocks in driving particle acceleration far beyond the immediate shock transition region, expanding the acceleration region to a larger spatial domain. Finally, this study underscores the importance of a multiscale observational approach in understanding the convoluted processes behind collisionless shock physics and their broader implications.