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Heavy cold ions at Mars are gravitationally bound to the planet unless some process provides energy to them. Observations show that cold (<20 eV) and dense (∼>1 cm−3) O+/O2+ ions with bulk velocities equal to energies ∼1 keV can reach deep into the nightside Martian magnetosheath. These ions are co‐located with a change of the sign of the sunward component of the magnetic field. This magnetic field topology implies the persistence of a localized planetary ions escape channel associated with draped magnetic field lines that are convecting tailward. The observed ion populations propagate approximately in the same direction as surrounding magnetosheath flow and are likely to be almost unheated ionospheric ions from low altitudes. The paper discusses planetary ion energization via Hall electric field originated from ions and electron separation associated with magnetic field curvature. Plain Language Summary In‐situ observations above the nightside of Mars show the presence of localized dense planetary ion fluxes at altitudes exceeding 2,000 km and escaping from the planet at high energies, comparable to that of the solar wind. These fluxes are accompanied by the reversal of sunward component of magnetic field. Unlike most atmospheric escape channels, the reported phenomenon is characterized by an increase in heavy to light ions density ratio with the distance from the planet at the observed altitudes up to nearly 5,000 km, as well as an increase in overall plasma number density inside this escape channel relative to the ambient sheath environment. This behavior is consistent with acceleration process initiated by a bent magnetic flux tube. Key Points Ions of different species gain similar energies in the Martian magnetosheath by Hall electric fields associated with magnetic curvature A high concentration of ionospheric ions correlates with a near void of shocked solar wind protons and a magnetic field reversal Number density at the reversal increases with distance from Mars in comparison to the surrounding sheath at least till two Martian radii

The interaction between planets and stellar winds can lead to atmospheric loss and is, thus, important for the evolution of planetary atmospheres 1 . The planets in our Solar System typically interact with the solar wind, whose velocity is at a large angle to the embedded stellar magnetic field. For planets without an intrinsic magnetic field, this interaction creates an induced magnetosphere and a bow shock in front of the planet 2 . However, when the angle between the solar wind velocity and the solar wind magnetic field (cone angle) is small, the interaction is very different 3 . Here we show that when the cone angle is small at Mars, the induced magnetosphere degenerates. There is no shock on the dayside, only weak flank shocks. A cross-flow plume appears and the ambipolar field drives planetary ions upstream. Hybrid simulations with a 4° cone angle show agreement with observations by the Mars Atmosphere and Volatile Evolution mission 4 and Mars Express 5 . Degenerate, induced magnetospheres are complex and not yet explored objects. It remains to be studied what the secondary effects are on processes like atmospheric loss through ion escape. When the cone angle between the solar wind velocity and the solar wind magnetic field is small at Mars, the induced magnetosphere degenerates.

When the cone angle of the interplanetary magnetic field (IMF) becomes small, induced magnetospheres of unmagnetized planets degenerate. Using hybrid simulations, we study ionospheric ion escape in a 4° cone angle case and compare it with the nominal 55° cone angle (Parker spiral) case. The total escape rate is 1.7×1025 $1.7\\times 1{0}^{25}$ s−1 ${\\mathrm{s}}^{-1}$, nearly an order of magnitude higher than the nominal rate of 2.2×1024 $2.2\\times 1{0}^{24}$ s−1 ${\\mathrm{s}}^{-1}$. The escape probability is four times higher. The unique feature of the degenerate induced magnetosphere is the upstream escape driven by the ambipolar electric field, contributing 42% to the total escape, a channel absent in the nominal case. Additionally, 52% of escape occurs through a cross‐flow plume, formed by the drift of ionospheric ions in the weak convective field and IMF. This channel is dominant, exhibiting an intensity seven times greater than that of the plume driven by the convective electric field in the nominal case.

The Martian magnetotail is a dynamic region where several processes contribute to plasma acceleration. Here, we analyze ∼5 ${\\sim} 5$ years of Mars Atmosphere and Volatile EvolutioN (MAVEN) data to evaluate the role of magnetic tension forces in driving plasma acceleration within current sheets in the tail. Based on magnetic field measurements, we identify 547 current sheet crossings that follow a Harris profile and find that the median observed current sheet density is ∼ ${\\sim} $110 nA m−2 ${\\mathrm{m}}^{-2}$, with a typical sheet width of ∼ ${\\sim} $100 km. We estimate a median normalized |〈Bn〉| $\\vert \\langle {B}_{n}\\rangle \\vert $ of ∼ ${\\sim} $0.1, and J×Bn $\\mathbf{J}\\times {\\mathbf{B}}_{n}$ force of ∼10−16 ${\\sim} 1{0}^{-16}$ N m−3 ${\\mathrm{m}}^{-3}$, capable of accelerating planetary ions within the sheets to ∼ ${\\sim} $1 keV over ∼ ${\\sim} $2 RM ${\\mathrm{R}}_{M}$. We also analyze plasma energization signatures in nine high‐Bn ${\\mathbf{B}}_{n}$ case studies and find they can be explained by work done by J×Bn $\\mathbf{J}\\times {\\mathbf{B}}_{n}$, although observed ion differential streaming suggests additional forces may be present.

We analyzed six Kelvin‐Helmholtz (K‐H) vortex events from Mars Atmosphere and Volatile EvolutioN (MAVEN) measurements. We found that fully developed vortices can occur at Mars' equatorial flanks and in the southern hemisphere, while they were previously observed only in the northern hemisphere. This implies that they do not exhibit a hemispheric asymmetry, and may occur globally as long as onset conditions are satisfied. We also estimated growth rates of 10−3 $1{0}^{-3}$–10−2 $1{0}^{-2}$ s−1 ${\\mathrm{s}}^{-1}$, and found that the inclusion of heavy planetary ions reduces growth rates while increasing the directions over which K‐H instability occurs. We calculated instantaneous ion loss rates due to detachment of K‐H vortices of 1025 $1{0}^{25}$–1027 $1{0}^{27}$ s−1 ${\\mathrm{s}}^{-1}$, rivaling other loss mechanisms in contributing to Mars' global atmospheric escape. The inferred higher occurrence rate of K‐H instability at Mars over a larger spatial domain strongly suggests a more significant contribution to overall atmospheric loss than previously thought.

The solar wind upstream of Mars's bow shock can be described in terms of Alfvénic turbulence, with an incompressible energy cascade rate of \\(10^{-17}\\) J m\\(^{-3}\\) s\\(^{-1}\\) at magnetohydrodynamics (MHD) scales. The solar wind has more Alfvén waves propagating outwards from the Sun (than inwards) and a median Alfvén ratio of \\(\\sim0.33\\). Newly ionized planetary protons associated with the extended hydrogen corona generate waves at the local proton cyclotron frequency. These 'proton cyclotron waves' (PCW) mostly correspond to fast magnetosonic waves, although the ion cyclotron (Alfvénic) wave mode is possible for large Interplanetary Magnetic Field cone angles. PCW do not show significant effects on the solar wind energy cascade rates at MHD scales but could affect smaller scales. The magnetosheath displays high amplitude wave activity, with high occurrence rate of Alfvén waves. Turbulence appears not fully developed in the magnetosheath, suggesting fluctuations do not have enough time to interact in this small-size region. Some studies suggest PCW affect turbulence in the magnetosheath. Overall, wave activity is reduced inside the magnetic pile-up region and the Martian ionosphere. However, under certain conditions, upstream waves can reach the upper ionosphere. So far, there have not been conclusive observations of Alfvén waves in the ionosphere or along crustal magnetic fields, which could be due to the lack of adequate observations.

Considers the recent increase of violence in the workplace, citing specific situations. Outlines the impact on the workplace in relation to areas such as morale, productivity, communication and responsibility. Covers the legal obligations and responsibilities of employers before profiling a case study of a government department. Provides details of the assessment and the findings together with recommendations for future improvement.

Understanding the formation and evolution of planetary bodies is of great interest and importance to humankind. Mars, being the closest analogue to Earth in our solar system, has been of particular importance. Having studied the red planet for many decades using landers and orbiting spacecraft, we are now laying the groundwork to venture there ourselves. The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission recently went into Mars orbit to study the physical processes active within the Martian atmosphere, and to understand how the atmosphere itself has evolved throughout the planet's history. This thesis is based upon unraveling data from the MAVEN mission, with a focus on the structure and energetics of the Martian ionosphere. Data from many of the instruments carried by MAVEN have been analyzed in this work, in particular, analysis and fitting of current-voltage sweeps measured by the Langmuir Probe and Waves instrument. New insights have been gained about the operation of Langmuir probes in planetary ionospheres, and through first author papers, about the Martian ionosphere itself. The four papers presented in this thesis focus on the structure and energetics of the Martian ionosphere. The first in-situ observations of the Martian nightside electron density and temperature showed that an ionization source is needed to sustain the observed densities. Precipitating electrons were shown as a feasible source, agreeing with suggestions from previous modeling efforts. The transfer of energy from the solar wind to the atmosphere is an important energy source for the Martian atmosphere. An investigation of the electromagnetic environment at Mars shows how the distribution of wave power, and various plasma boundaries within the Martian magnetosphere, respond to upstream solar wind conditions, highlighting regions important for energy dissipation. The combination of magnetic field and ion data allows for the first time at Mars, ion conics to be observed. These show evidence of parallel acceleration and ion heating present at low altitudes in the ionosphere. Finally, an investigation of sporadic disturbances observed below the Martian exobase showed that the Rayleigh-Taylor instability is present in the Martian ionosphere. Similar disturbances are present in the terrestrial ionosphere and are known as Equatorial Spread F (ESF). Such disturbances cause communication problems within the terrestrial ionosphere and similar problems may occur when humans reach the surface of the red planet.

Thermal (<1 eV) electron density measurements, derived from the Mars Atmosphere and Volatile Evolution's (MAVEN) Langmuir Probe and Waves (LPW) instrument, are analyzed to produce the first statistical study of the thermal electron population in the Martian magnetotail. Coincident measurements of the local magnetic field are used to demonstrate that close to Mars, the thermal electron population is most likely to be observed at a cylindrical distance of ~1.1 Mars radii (RM) from the central tail region during times when the magnetic field flares inward toward the central tail, compared to ~1.3 RM during times when the magnetic field flares outward away from the central tail. Similar patterns are observed further down the magnetotail with greater variability. Thermal electron densities are highly variable throughout the magnetotail; average densities are typically ~20-50 /cc within the optical shadow of Mars and can peak at ~100 /cc just outside of the optical shadow. Standard deviations of 100% are observed for average densities measured throughout the tail. Analysis of the local magnetic field topology suggests that thermal electrons observed within the optical shadow of Mars are likely sourced from the nightside ionosphere, whereas electrons observed just outside of the optical shadow are likely sourced from the dayside ionosphere. Finally, thermal electrons within the optical shadow of Mars are up to 20% more likely to be observed when the strongest crustal magnetic fields point sunward than when they point tailward.