We performed 2D PIC simulations of Kelvin Helmholtz instability (KHI) with symmetric and asymmetric density and temperature profiles along the flow shear with a northward interplanetary magnetic field. The Magnetic Flux Transport method, field topology and magnetic field minimums are used to identify the reconnection X-lines. We start to observe the reconnection signatures such as magnetic field and flow reversals at the vortex edges in the nonlinear phase of the KHI when the vortices are rolling up. The number of reconnection regions increases at the turbulence phase. The signatures eventually decrease and finally disappear at very turbulent stages of KHI developments. Our results qualitatively agree with MMS observations of reconnection signatures at KHI along the magnetospheric flanks.

Calculating the pressure-strain terms has recently been performed to quantify energy conversion between the bulk flow energy and the internal energy of plasmas. It has been applied to numerical simulations and satellite data from the Magnetospheric MultiScale Mission. The method requires spatial gradients of the velocity and the use of the full pressure tensor. Here we present a derivation of the errors associated with calculating the pressure-strain terms from multi-spacecraft measurements and apply it to previously studied examples of magnetic reconnection at the magnetopause and the magnetotail. The errors are small in a dense magnetosheath event but much larger in the more tenuous magnetotail. This is likely due to larger counting statistics in the dense plasma at the magnetopause than in the magnetotail. The propagated errors analyzed in this work are important to understand uncertainties of energy conversion measurements in space plasmas and have applications to current and future multi-spacecraft missions.

While not specifically designed as a planetary mission, NASA’s Parker Solar Probe (PSP) mission uses a series of Venus gravity assists (VGAs) in order to reduce its perihelion distance. These orbital maneuvers provide the opportunity for direct measurements of the Venus plasma environment at high cadence. We present first observations of kinetic scale turbulence in the Venus magnetosheath from the first two VGAs. In VGA1, PSP observed a quasi-parallel shock, $\beta\sim1$ magnetosheath plasma, and a kinetic range scaling of $k^{-2.9}$. VGA2 was characterised by a quasi-perpendicular shock with $\beta\sim 10$, and a steep $k^{-3.4}$ spectral scaling. Temperature anisotropy measurements from VGA2 suggest an active mirror mode instability. Significant coherent waves are present in both encounters at sub-ion and electron scales. Using conditioning techniques to exclude these electromagnetic wave events suggests the presence of developed sub-ion kinetic turbulence in both magnetosheath encounters.

Plasmas in Earth’s outer magnetosphere, magnetosheath, and solar wind are essentially collisionless. This means particle distributions are not typically in thermodynamic equilibrium and deviate significantly from Maxwellian distributions. The deviations of these distributions can be further enhanced by plasma processes, such as shocks, turbulence, and magnetic reconnection. Such distributions can be unstable to a wide variety of kinetic plasma instabilities, which in turn modify the electron distributions. In this paper the deviations of the observed electron distributions from a bi-Maxwellian distribution function is calculated and quantified using data from the Magnetospheric Multiscale (MMS) spacecraft. A statistical study from tens of millions of electron distributions shows that the primary source of the observed non-Maxwellianity are electron distributions consisting of distinct hot and cold components in Earth’s low-density magnetosphere. This results in large non-Maxwellianities in at low densities. However, after performing a stastical study we find regions where large non-Maxwellianities are observed for a given density. Highly non-Maxwellian distributions are routinely found are Earth’s bowshock, in Earth’s outer magnetosphere, and in the electron diffusion regions of magnetic reconnection. Enhanced non-Maxwellianities are observed in the turbulent magnetosheath, but are intermittent and are not correlated with local processes. The causes of enhanced non-Maxwellianities are investigated.

The Mars Atmosphere and Volatile EvolutionN (MAVEN) spacecraft can act as an intermittent upstream solar wind monitor at ~ 1.5 AU. To inspect the evolution of solar wind turbulence in the Martian exosphere, we have gathered proton (i.e., ionized hydrogen) temperature measurements taken by the Solar Wind Ion Analyzer (SWIA) onboard the MAVEN spacecraft. Here we investigate instabilities driven by the proton temperature anisotropy at Mars. We look at the temperature anisotropy T⊥p/T||p (i.e., the ratio of the perpendicular proton temperature component to the parallel proton temperature component) and the parallel plasma beta, β||p, to determine the active plasma instability mode. Furthermore, we report on the properties of turbulence near Mars’ orbital location during upstream solar wind intervals from January 2015 to December 2016 (~ 1 Martian year). We find that the probability distributions of (β||p, Rp)-values are limited at Rp >1 and Rp <1. We also find evidence of intermittency implying nonlinear, non-homogeneous energy transfer. Additionally, spectral index values near the Kolmogorov scaling value are observed for the inertial range (10-4 Hz to 0.1 Hz).

We exploit novel “string-of-pearls” configuration of NASA’s Magnetospheric Multiscale mission to investigate properties of structures within the Earth’s magnetosheath that are short in duration but carry intense currents. Previous work has shown that the j.E energy conversion within current structures processes of order 10% of the total energy flux incident at the bow shock. This makes these events important contributors to the overall shock energy budget and ongoing thermalization within the magnetosheath. The present study, under very similar solar wind conditions and bow shock geometries, reveals significant qualitative differences from the previous study. Moreover, we find only modest, if any coherence, on scales <1000 km. We explore the implication of these observations in terms of both bow shock and turbulence energy transfer and dissipation.