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[Introduction] By adding parallel electron viscosity into the normal equation of resistance tearing mode, the nonlinear behavior of double tearing mode (DTM) mediated by parallel electron viscosity is numerically investigated considering the magnetohydrodynamics in a periodic cylinder. [Method] The evolution of magnetic islands and magnetic flux during the nonlinear behavior stage of double tearing mode mediated by parallel electron viscosity were analyzed, to study the changes of the magnetic field topology in different phases and associated kinetic characteristics for different distances between the two resonant rational flux surfaces. In addition, the nonlinear driving for each case was discussed. [Result] The results show that the distance between the two resonant rational flux surfaces has a significant impact on the nonlinear behavior of double tearing mode. Rapid magnetic reconnection would occur at an intermediate distance, resulting in the fastest and most severe damage to the configuration. [Conclusion] The results of this study provide a reference for the configuration design and operational control of tokamaks.

Magnetic reconnection and plasma waves share a critical connection. On the one hand, quasi-steady wave structures (shock, KAW eigenmode) play a pivotal role in the formation and structure of magnetic reconnection. On the other hand, higher-frequency and small-scale waves may influence energy conversion, particle heating, and anomalous resistivity. Waves of various scales dictate the multi-scale coupling characteristics and energy conversion within the reconnection process. This review focuses on plasma waves during the Earth's magnetosphere magnetic reconnection, seeking to elucidate the characteristics and roles of kinetic Alfven waves (KAW), low hybrid waves, whistler waves, electrostatic solitary waves (ESWs), ion acoustic waves, and electron-scale high-frequency electrostatic waves. The KAW eigenmode is capable of describing various phenomena in the diffusion region such as Hall magnetic fields and Hall electric fields, significantly impacting the reconnection rate. Lower hybrid waves are easily excited in the strong density gradient in the current layer and found to heat electrons in the parallel direction, while whistler waves are excited through Landau resonance and cyclotron resonance. Both whistler waves and lower hybrid waves are found to exhibit minimal influence on the reconnection rate through the anomalous resistivity. ESWs predominantly emerge within the magnetic reconnection boundary region, necessitating further investigation into their heating effects. Finally, the review delves into high-frequency electrostatic waves, emphasizing their importance in the magnetic reconnection diffusion region, specifically for electron diffusion and scattering processes. The insights gained from these research advancements serve as a foundation for future studies and advancements in the field of magnetic reconnection and plasma wave interactions.

The collisionless Keda Reconnection eXperiment (KRX) is a comprehensive platform for ground-base simulations of basic physical processes in a space environment. Its purpose is to reveal the triggering mechanism and electron diffusion structure of collisionless magnetic field reconnection and to study the associated plasma waves. The KRX is a linear device with a capsule-shaped vacuum chamber of 3 m diameter and composed of several sections. The world's largest oxide cathode source (2 m × 1 m) was used to produce a uniform background plasma. The KRX was surrounded by ten groups of guided field magnetic coils. Meanwhile, the reconnection magnetic field configuration was constructed using two parallel current plates with the same pulse current, which were installed on the upper and lower parts of the device. In addition, the pulse power supply adopted an H-shaped bridge structure to realize the controllable variable rate reconnection drive. More than 200 vacuum windows surround the device. The magnetic-field reconnection process can be measured using a probe array and other advanced optical diagnostics, including a THz polarimeter/interferometer and laser-induced fluorescence. KRX is the latest generation of magnetic-reconnection experiment platforms and is particularly useful for collisionless magnetic reconnection experiments. The reconnection area reaches 10 times the ion inertia length, and the Lundquist number is expected to reach 105. Global, active, and high-precision diagnostic measurements make multiscale, comprehensive research on magnetic field reconnection possible by addressing the shortcomings of satellite observations and numerical simulations. At present, the construction of the experimental platform and key components, such as diagnostics, have been completed. A research scheme of multi-scale, multi-magnetic island merger, 3D magnetic field reconnection, and other important issues is proposed based on the preliminary small-scale results of the research device.

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Copyright of Reviews of Geophysics & Planetary Physics is the property of Editorial Office of Reviews of Geophysics & Planetary Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Reviews of Geophysics & Planetary Physics is the property of Editorial Office of Reviews of Geophysics & Planetary Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Magnetic reconnection is one of the important physical mechanisms for the conversion of magnetic energy into plasma energy, which is closely related to many explosive phenomena in space. Magnetic reconnection is a cross-scale physical process, in which the physical process at the electron-scale plays key roles in triggering reconnection and facilitating reconnection fast, hence it has attracted much attention. After the launch of the magnetospheric multiscale (MMS) satellite in 2015, the unprecedented high-resolution data provided by MMS enable us to have a new understanding of the electron-scale physics. This paper briefly summarizes the recent research progresses of electron-scale physics in magnetic reconnection based on the observational results of MMS. We divided the reconnection region into the electron diffusion region, ion diffusion region and reconnection exhaust, and summarized the electron scale physical processes from many aspects. The main contents are as follows: The electron diffusion region can form a multiple structure in the inflow or outflow direction, and its formation process may involve a variety of instabilities; The crescent distribution in the electron diffusion region is affected by many factors, such as Hall electric field and electron meandering motion, so that the electron distribution function in this region no longer presents a crescent distribution in some cases; Plasma waves in the electron diffusion region can effectively heat electrons and provide anomalous resistance to break the frozen-in conditions, which plays a key role in reconnection; The non-ideal electric field in the electron diffusion region can be balanced by the electron pressure tensor term, but the anomalous resistance term may dominate in some events; The formation and evolution of electron scale coherent structures in the ion diffusion region are very important for energy conversion and dissipation, including the turbulence driven by the merging of magnetic islands, the secondary reconnection triggered by Kelvin-Helmholtz instability and the formation of kinetics scale magnetic holes; The coalescence of magnetic flux ropes and the magnetic reconnection between the magnetic flux ropes and the geomagnetic field in the reconnection exhaust can release the magnetic energy through multi-scale coupling, and the generation of high-energy electrons can be excited in the magnetic flux ropes through a variety of acceleration mechanisms; Near the reconnection front, there are often various plasma instabilities and strong current structures, which play an important role in the release of magnetic energy. In addition, we briefly discuss the triggering mechanism of magnetic reconnection at the electron-scale, such as the electron-only reconnection in turbulence and reconnection driven by electron kinetics in the magnetotail. Finally, we discuss the importance of multi-scale coupling in magnetic reconnection and some key open questions.

Among the eight solar system planets, Jupiter and Saturn are the two most giant planets, which also have the most prominent magnetic moments. Comparing to the Earth dipole magnetic field, the magnetic moment of Saturn is about 600 times larger while Jupiter is about 20 000 times larger. The extremely large magnetic moments of giant planets sustain giant planetary magnetospheres, trapping energetic particles with constant electromagnetic perturbations. In this article, we will review the basic pictures of mass and energy circulations in giant planetary space environments, energetic plasma processes in radiation belt, magnetosphere-ionosphere coupling processes and fundamental plasma processes in magnetospheres.