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Mars lacks a global intrinsic dipole field but possesses localized crustal fields, making it unique in the solar system. Recent observations revealed that electrons can be injected into the crustal fields, and exhibit drift-dispersed bursts due to the magnetic drift motion, which are characterized by increases or decreases in energy over time in the energy spectrum. However, the source of the drift-dispersed electrons and the mechanism of their injection into the crustal fields remains unclear. Here, by leveraging data from the Mars Atmosphere and Volatile EvolutioN mission, along with test-particle simulations, we reveal that the source of dispersed electrons is the precipitating electrons injected into the crustal fields via open field lines. These electrons display as dispersionless bursts near the source location, and as dispersed bursts as they drift away from the source. Thus, the dispersed electrons represent a later stage in the evolution of dispersionless electrons. This evolutionary process closely mirrors that observed within Earth's dipole field, affirming that the crustal fields function similarly to a mini-magnetosphere. [ABSTRACT FROM AUTHOR]

Graphene foam composite is a promising candidate for advanced thermal management applications due to its excellent mechanical strength, high thermal conductivity, ultra-high porosity and huge specific surface area. In this study, a three-dimensional physical model was developed in accordance with the dodecahedral structure of graphene foam composite. A comprehensive numerical simulation was carried out to investigate the fluid flow and convective heat transfer in open-cell graphene foam composite by using ANSYS Fluent 2021 R1 commercial software. Research results show that, as porosity increases, the pressure gradient for graphene foam composite with circular and triangular cross-section struts is reduced by 65% and by 77%, respectively. At a given porosity of 0.904, when the inlet velocity increases from 1 m/s to 5 m/s, the pressure gradient is increased by 11.3 times and 13.8 times, and the convective heat transfer coefficient is increased by 54.5% and 43% for graphene foam composite with circular and triangular cross-section struts, respectively. Due to the irregularity of the skeleton distribution, the pressure drop in Y direction is the highest among the three directions, which is 8.7% and 17.4% higher than that in the Z and X directions at the inlet velocity of 5 m/s, respectively. The convective heat transfer coefficient in the Y direction is significantly lower than that along the X and Z directions. Furthermore, triangular cross-section struts induce a greater pressure drop but offer less effective heat transfer compared to circular struts. The research findings may provide critical insights into the design and optimization of graphene foam composites, and promote their potential for efficient thermal management and gas/liquid purification in engineering applications. [ABSTRACT FROM AUTHOR]

Simulations of the coupled ionosphere-magnetosphere system are a key tool to understand geospace and its response to space weather. For the most part, they are based on fluid descriptions of plasma (magnetohydrodynamics, MHD) formalism, coupled an electrostatic ionosphere. Kinetic approaches to modeling the global magnetosphere with a coupled ionosphere system are still a rarity. We present an ionospheric boundary model for the global near-Earth plasma simulation system Vlasiator. It complements the magnetospheric hybrid-Vlasov simulations with an inner boundary condition that solves the ionospheric potential based on field-aligned current and plasma quantities from the magnetospheric domain. This new ionospheric module solves the ionospheric potential in a height-integrated approach on an unstructured grid and couples back to the hybrid-kinetic simulation by mapping the resulting electric field to the magnetosphere's inner boundary. The solver is benchmarked against a set of well-established analytic reference cases, and we discuss the benefits of a spherical Fibonacci mesh for use in ionospheric modeling. Preliminary results from coupled global magnetospheric-ionospheric simulations are presented, showing formation of both Region 1 and Region 2 current systems. [ABSTRACT FROM AUTHOR]

Magnetosonic (MS) waves, i.e., ion Bernstein mode waves, are one of the common plasma waves in the Earth's magnetosphere, which are important for regulating charged particle dynamics. How MS waves propagate in the magnetosphere is critical to understanding the global distribution of the waves, but it remains unclear. Although previous studies present that MS waves can be reflected by fine-scale density structures, the dissipation of waves by background plasma has long been neglected. In this study, we perform one-dimensional (1-D) particle-in-cell (PIC) simulations to study the propagation of MS waves through density structures, where both absorption and reflection have been included. We find that absorption is as important as reflection when considering the propagation of MS waves through density structures, and both of them are strongly dependent on the shape of density structures. Specifically, the reflectivity of MS waves is positively and negatively correlated with the height and width of density structures, respectively, while the absorptivity of MS waves has a positive correlation with both the height and width of density structures. Our study demonstrates the significance of absorption during the propagation of MS waves, which may help better understand the distribution of MS waves in the Earth's magnetosphere. [ABSTRACT FROM AUTHOR]

The precipitation of charged particles from the magnetosphere into the ionosphere is one of the crucial coupling mechanisms between these two regions of geospace and is associated with multiple space weather effects, such as global navigation satellite system signal disruption and geomagnetically induced currents at ground level. While precipitating particle fluxes have been measured by numerous spacecraft missions over the past decades, it often remains difficult to obtain global precipitation patterns with a good time resolution during a substorm. Numerical simulations can help to bridge this gap and improve the understanding of mechanisms leading to particle precipitation at high latitudes through the global view they offer on the near-Earth space system. We present the first results on auroral (0.5–50 keV) proton precipitation within a 3-dimensional simulation of the Vlasiator hybrid-Vlasov model. The run is driven by southward interplanetary magnetic field conditions with constant solar wind parameters. We find that on the dayside, cusp proton precipitation exhibits the expected energy–latitude dispersion and takes place in the form of successive bursts associated with the transit of flux transfer events formed through dayside magnetopause reconnection. On the nightside, the precipitation takes place within the expected range of geomagnetic latitudes, and it appears clearly that the precipitating particle injection is taking place within a narrow magnetic local time span, associated with fast Earthward plasma flows in the near-Earth magnetotail. Finally, the simulated precipitating fluxes are compared to observations from Defense Meteorological Satellite Program spacecraft during driving conditions similar to those in the simulation and are found to be in good agreement with the measurements.

In this study, a novel system which integrates solar thermal energy with membrane gas absorption technology is proposed to capture CO2 from a 580 MWe pulverized coal power plant. Technical feasibility and economic evaluation are carried out on the proposed system in three cities with different solar resources in China. Research results show that the output capacity and net efficiency of the SOL-HFMC power plant are significantly higher than those of the reference power plant regardless of whether a TES system is applied or not. In addition, the CEI of the SOL-HFMC power plant with the TES system is 4.36 kg CO2/MWh, 4.45 kg CO2/MWh and 4.66 kg CO2/MWh lower than that of the reference power plant. The prices of the membrane, vacuum tube collector and phase change material should be reduced to achieve lower LCOE and COR values. Specifically for the SOL-HFMC power plant with the TES system, the corresponding vacuum tube collector price shall be lower than 25.70 $/m2 for Jinan, 95.20 $/m2 for Xining, and 128.70 $/m2 for Lhasa, respectively. To be more competitive than a solar-assisted ammonia-based post-combustion CO2 capture power plant, the membrane price in Jinan, Xining and Lhasa shall be reduced to 0.012 $/m, 0.015 $/m and 0.016 $/m for the sake of LCOE, and 0.03 $/m, 0.033 $/m and 0.034 $/m for the sake of COR, respectively. [ABSTRACT FROM AUTHOR]

Magnetic reconnection is a crucially important process for energy conversion in plasma physics, with the substorm cycle of Earth's magnetosphere and solar flares being prime examples. While 2D models have been widely applied to study reconnection, investigating reconnection in 3D is still, in many aspects, an open problem. Finding sites of magnetic reconnection in a 3D setting is not a trivial task, with several approaches, from topological skeletons to Lorentz transformations, having been proposed to tackle the issue. This work presents a complementary method for quasi-2D structures in 3D settings by noting that the magnetic field structures near reconnection lines exhibit 2D features that can be identified in a suitably chosen local coordinate system. We present applications of this method to a hybrid-Vlasov Vlasiator simulation of Earth's magnetosphere, showing the complex magnetic topologies created by reconnection for simulations dominated by quasi-2D reconnection. We also quantify the dimensionalities of magnetic field structures in the simulation to justify the use of such coordinate systems. [ABSTRACT FROM AUTHOR]