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Induced magnetospheres form around planetary bodies with atmospheres through the interaction of the solar wind with their ionosphere. Induced magnetospheres are highly dependent on the solar wind conditions and have only been studied with single spacecraft missions in the past. Without simultaneous measurements of solar wind variations and phenomena in the magnetosphere, establishing a link between both can only be done indirectly, using statistics over a large set of measurements. This gap in knowledge could be addressed by a multi-spacecraft plasma mission, optimized for studying global spatial and temporal variations in the magnetospheric system around Venus, which hosts the most prominent example of an induced magnetosphere in our solar system. The MVSE mission comprises four satellites, of which three are identical scientific spacecraft, carrying the same suite of instruments probing different regions of the induced magnetosphere and the solar wind simultaneously. The fourth spacecraft is the transfer vehicle which acts as a relay satellite for communications at Venus. In this way, changes in the solar wind conditions and extreme solar events can be observed, and their effects can be quantified as they propagate through the Venusian induced magnetosphere. Additionally, energy transfer in the Venusian induced magnetosphere can be investigated. The scientific payload includes instrumentation to measure the magnetic field, electric field, and ion–electron velocity distributions. This study presents the scientific motivation for the mission as well as requirements and the resulting mission design. Concretely, a mission timeline along with a complete spacecraft design, including mass, power, communication, propulsion and thermal budgets are given. This mission was initially conceived at the Alpbach Summer School 2022 and refined during a week-long study at ESA's Concurrent Design Facility in Redu, Belgium. • Multi-spacecraft plasma physics mission concept to Venus. • Dynamics of induced magnetospheres due to variations in the solar wind. • Magnetospheric reaction due to extreme solar events. [ABSTRACT FROM AUTHOR]

• Development of next generation of active spacecraft potential control (ASPOC-NG). • One instrument for positive and negative spacecraft charge compensation. • Coupling test of ASPOC-NG instrument, including accuracy and lifetime test. • Low resource potential control device as candidate for future science missions. The active spacecraft potential control (ASPOC) system developed in the 1990s emits positive ions to neutralise the spacecraft potential, such as used in several missions like Geotail, Equator-S, Cluster, Doublestar and MMS. With the experience gained, the next generation of the active spacecraft potential control (ASPOC-NG) instrument has been developed over the last three years. Thereby, three emission technologies were tested including Liquid Metal Ion Source (LMIS), Liquid Metal Electron Source (LMES) and Solid Metal Electron Source (SMES). The development of the emitter module by FOTEC and the corresponding electronics control unit by IWF is presented. Optimisations were carried out with the focus on the reduction of mass and power consumption to comply with the requirements of future scientific missions. Coupling tests of the modules and the electronics control unit were performed including range, accuracy and lifetime tests. Both ASPOC-NG instruments for positive and negative charge compensation and their performance values show excellent results. [ABSTRACT FROM AUTHOR]

Abstract: A model is presented that describes the excitation of small-scale density perturbations and electromagnetic fields by standing shear Alfvén waves in a Cartesian geometry. The model includes the effects of plasma betas and the Hall term effects. The characteristics of magnetospheric density cavities and the formation of the significant peak in density are discussed in the paper. [Copyright &y& Elsevier]

Abstract: Acceleration of charged particles in magnetic field-aligned electric potential differences at Earth and at the outer planets in the solar system is summarized and its general importance in the Universe is briefly discussed. The role of field-aligned currents, driven by parallel electric fields, in causing filamentary structure in stellar atmospheres is briefly reviewed. The differences between auroral optical emissions at various planets are summarized. The important role of field-aligned potential differences in the generation of AKR and corresponding emissions from other objects is discussed. Finally, aurora-associated processes for ejection of planetary plasma into space are briefly reviewed. [Copyright &y& Elsevier]

Abstract: The spatial distribution of MHD discontinuities in the solar wind has been studied, based on the long time observations by the magnetometer onboard Ulysses. We emphasize the critical importance of the method whereby events are selected; some previous work is critically reviewed in this respect. Our analysis supports earlier observations that the density of discontinuities decreases with increasing distance from the Sun. It is suggested, however, that the distribution of the discontinuity normals should be revised, retaining only those discontinuities for further study that have reliable normals. This study shows that the vast majority of well defined discontinuities has a small magnetic field component parallel to the discontinuity normal. Given the large number of discontinuities in the Ulysses data set there is a statistically sufficient number for further study. It is also shown in this paper that for the subset of well defined discontinuities the determination of the normal vector using Minimum Variance Analysis and the cross-product technique are equally valid. [Copyright &y& Elsevier]

Abstract: By direct numerical simulations we investigate the nonlinear dynamics of a compressible Hall Magnetohydrodynamic (MHD) plasma. At small scales, where the Hall effect dominates, we found an increase of the compressibility of the system and the breakdown of the strong link between velocity and magnetic fields, typical of usual MHD. Moreover, we find that small-scale fluctuations are characterized by an anti-correlation between density and magnetic field intensity. These features characterize the excitation of a quasi-perpendicular magnetosonic turbulence that can be interpreted as the small-scale signature of the break-down of the MHD nonlinear energy cascade due to Hall effect. Fluctuations with the same properties, based on measurements by Cluster spacecraft in space plasma turbulence during different magnetopause crossings, have been recently observed. [Copyright &y& Elsevier]

Abstract: The interplanetary medium is characterized by a very high Reynolds number and is pervaded by fluctuations providing information on a wide range of scales, from fractions of second up to the solar rotation period. In the past decade or so, turbulence in the solar wind has been used as a large wind tunnel to investigate scaling laws of turbulent fluctuations and multifractal models. Moreover, new interesting insights in the theory of turbulence have been derived from the point of view which considers a turbulent flow as a complex system, a sort of benchmark for the theory of dynamical systems. Important finding like the lack of a strict self-similarity of the fluctuations with the consequent nonapplicability of strict scale invariance, the strong anisotropy of velocity and magnetic field fluctuations, the clear lack of equipartition between magnetic and kinetic fluctuations all contributed to suggest the idea that interplanetary fluctuations could possibly be due to a mixture of propagating waves and static structures convected by the wind. In this paper we further discuss this point and bring new evidence about the fact that the presence of a background magnetic field introduces not only a symmetry breaking in interplanetary space but also organizes fluctuations about its large scale orientation. [Copyright &y& Elsevier]

Abstract: Turbulent spectrum of magnetic fluctuations in the solar wind nearly follows Kolmogorov''s law below the ion cyclotron frequency . Above this frequency, the observed steeper power law is believed to be a ‘dissipative range’ of the solar wind turbulence. In this paper we analyze magnetic field fluctuations measured onboard Cluster, lasting two decades above . Well-defined power law and a strong increase of intermittency with frequency in this range indicates that turbulence cannot be characterized by a ‘dissipative range’. Rather we conjecture that above the turbulence is generated by a different nonlinear cascade. We suggest that the presence of dispersive effects is responsible for a steepening of the spectral energy density, simply because a cascade can be realized in a time that is shorter than the usual eddy-turnover time. In the Hall MHD formulation, the magnetic power follows a law , which depends on the degree of plasma compressibility . [Copyright &y& Elsevier]

Abstract: A mechanism for enhancing the acceleration of electrons by considering the effect of a low amplitude electron cyclotron waves crossing a primary wave in an ambient magnetic field is investigated. The underlying idea is that a low amplitude secondary wave may improve the transfer of parallel momentum from the high amplitude primary wave to charged particles. An analytical approximation, referred to as the Resonant Moments (RM) method, is proposed to estimate the efficiency of the wave configuration. Based on the RM method, optimal configurations are proposed for the two-wave scheme in which the secondary wave should be launched perpendicularly to the external magnetic field. Direct statistical (particle Monte Carlo) simulations confirm that such a configuration can yield an increase of the mean electron velocity of one order of magnitude when compared to the one-wave configuration. It is a quite promising result because the amplitude of the secondary wave is 10 times lower than the one of the first wave. The parameters used are related to electron acceleration in planetary magnetospheres, ionospheres as well in magnetic plasma fusion experiments. [Copyright &y& Elsevier]

Abstract: MEFISTO, together with the companion instrument WPT, are planning the first-ever in situ measurements of the electric field in the magnetosphere of planet Mercury. The instruments have been selected by JAXA for inclusion in the BepiColombo/MMO payload, as part of the Plasma Wave Investigation coordinated by Kyoto University. The magnetosphere of Mercury was discovered by Mariner 10 in 1974 and will be studied further by Messenger starting in 2011. However, neither spacecraft did or will measure the electric field. Electric fields are crucial in the dynamics of a magnetosphere and for the energy and plasma transport between different regions within the magnetosphere as well as between the magnetosphere and the surrounding regions. The MEFISTO instrument will be capable of measuring electric fields from DC to 3MHz, and will thus also allow diagnostics of waves at all frequencies of relevance to the Hermean magnetosphere. MEFISTO is a double-probe electric field instrument. The double-probe technique has strong heritage and is well proven on missions such as Viking, Polar, and Cluster. For BepiColombo, a newly developed deployment mechanism is planned which reduces the mass by a factor of about 5 compared to conventional mechanisms for 15m long booms. We describe the basic characteristics of the instrument and briefly discuss the new developments made to tailor the instrument to flight in Mercury orbit. [Copyright &y& Elsevier]

Abstract: Returning to Mercury with the BepiColombo mission will provide a unique opportunity to obtain in situ information on the electric field in Mercury’s magnetosphere. The electric field plays a crucial role for plasma transport in the magnetosphere, for transfer of energy between different parts of the system, and for propagation of information. Measuring the electric field, we will be able to better understand plasma motion and wave propagation in Mercury’s magnetosphere. Together with knowledge of the magnetic field a better understanding will be derived of the magnetospheric current systems and their closure at or near the planetary surface. Further, insight into possible substorms at Mercury will be gained. We here focus on the expected amplitudes and frequencies of the electric fields concerned and the requirements for instrument capability that they pose. [Copyright &y& Elsevier]

In this paper we examine the motion of ions in the magnetotail current sheet, and the effect on that motion of both an average normal component to the current sheet and the presence of magnetic fluctuations. We find that these two quantities have competing effects on the ion motion, with the normal component causing the ions to be ejected from the current sheet and the fluctuations (under certain circumstances) causing the ions to have an increased residence time in the current sheet. We also consider the implications for particle energization and the resulting ion distributions in the lobes. [Copyright &y& Elsevier]