The roles of heavy ions have long been an important subject in the magnetospheric physics since the first discovery of O+ ions in the magnetosphere as it hinted to the connection between the ionospheric and magnetospheric plasma. Albeit limited, several observations show the importance of ionospheric N+ and molecular ions, including NO+, N2+ and O2+, in the high-altitude ionosphere and magnetosphere. However, the mechanisms responsible for accelerating the ionospheric heavy ions from eV to keV energies are still largely unknown. Developed from the Polar Wind Outflow Model (PWOM), the Seven Ion Polar Wind Outflow Model (7iPWOM) solves the gyrotropic transport equations for all relevant species (e-, H+, He+, N+, O+, N2+, NO+ and O2+) along open magnetic field lines and therefore, has the capability to assess the role of heavy ions in the supersonic ionospheric outflow. However, the hydrodynamic approach is limited to the region where collisions are important. For the altitudes above the collision-dominated region, the hydrodynamic solution becomes increasingly inadequate. Thus, the 7iPWOM applies a kinetic particle-in-cell (PIC) approach that enables the inclusion of wave-particle interactions (WPI) and Coulomb collisions. The simulation results showed that the N+ ions play a key role in the polar wind solution under all conditions. The mechanisms responsible for the energization of outflowing N+ ions are different than those of O+, not only in the collision-dominated region but also at high-altitudes. This means that the local heating sources to O+ and N+ in the polar wind, even in small amounts, can lead to plasma instability and could possibly affect the large-scale transport properties. In addition, the relative abundance of molecular ions, and how they change the polar wind solution, reveals the link between lower thermosphere and the ionosphere. Therefore, tracking the molecular ions helps understand how the “fast ion outflow” acquires sufficient energy in such a short time scale, compared with the dissociative recombination lifetime of the molecular ions, and assess the role of molecular ions in the overall dynamics of the polar wind outflow.

Nitrogen is the most abundant element in the Earth’s atmosphere. Around 78% N2; and 21% O2; form the air we breathe and expand into high-altitude atmosphere, the thermosphere, and eventually the ionosphere. The neutral molecules in the ionosphere are ionized by solar radiation, and some of them break up into atoms, and others become charged particles. The ionospheric ions with sufficient energy can flow out into space, and the abundances of these outflowing ionospheric ions highly impact the near-Earth plasma properties. Studies focused on outflowing O+ ions have been conducted for many years. However, the contribution of N+ to the outflow solution is still largely unknown due to the instrumental limitations. We developed a first-principled physics model to understand how N+ and molecular ions, including NO+, N2+, and O2+, acquire the sufficient energy to escape Earth’s atmosphere. This study reveals the importance of N+ ions in the high-altitude polar ionosphere, from few hundred kilometers to thousands of kilometers in the space, and examines the possible mechanisms to accelerate and removed them from Earth’s atmosphere.

The habitability of the surface of any planet is determined by a complex evolution of its interior, surface, and atmosphere. The electromagnetic and particle radiation of stars drive thermal, chemical and physical alteration of planetary atmospheres, including escape. Many known extrasolar planets experience vastly different stellar environments than those in our Solar system: it is crucial to understand the broad range of processes that lead to atmospheric escape and evolution under a wide range of conditions if we are to assess the habitability of worlds around other stars. One problem encountered between the planetary and the astrophysics communities is a lack of common language for describing escape processes. Each community has customary approximations that may be questioned by the other, such as the hypothesis of H-dominated thermosphere for astrophysicists, or the Sun-like nature of the stars for planetary scientists. Since exoplanets are becoming one of the main targets for the detection of life, a common set of definitions and hypotheses are required. We review the different escape mechanisms proposed for the evolution of planetary and exoplanetary atmospheres. We propose a common definition for the different escape mechanisms, and we show the important parameters to take into account when evaluating the escape at a planet in time. We show that the paradigm of the magnetic field as an atmospheric shield should be changed and that recent work on the history of Xenon in Earth’s atmosphere gives an elegant explanation to its enrichment in heavier isotopes: the so-called Xenon paradox.

Changes in the heavy ion composition in the terrestrial ionosphere and magnetosphere can have significant impact on particle dynamics in the Earth’s magnetosphere-ionosphere system. Most instruments flying in space, such as MMS and Van Allen Probes, lack the possibility to distinguish N+ from O+ due to their close masses. However, observations of N+ both in the ionosphere and magnetosphere indicate that N+ is a constant companion of O+ , especially during the storm time. Because N+ originates from the Earth’s ionosphere, we further develop the Polar Wind Outflow Model (PWOM) to investigate the behavior and acceleration mechanisms of heavy ions in Earth’s ionosphere. The PWOM solves the particle dynamics of O+, H+ and He+ in the ionospheric outflow and the modified PWOM can further simulate the behavior of N+ and N2+ in Earth’s polar wind. The escape of heavy ions from the Earth atmosphere is consequences of energization and transport mechanisms, including photo ionization, electron precipitation, ion-electron-neutral chemistry and collisions. The modified PWOM is coupled with a two-stream model of superthermal electrons (GLobal airglow, or GLOW) to deal with attenuated radiation, electron beam energy dissipation, and secondary electron impact. In this study, we show that during various solar conditions, the ion-electron-neutral densities in the ionospheric outflow show significant difference when we consider N+ ions in the polar wind. Furthermore, we will compare the simulation results of the modified PWOM with observation data for validation.

The Earth’s magnetosphere is filled by particles from two sources: the solar wind and the ionosphere. Ionospheric ions are initially cold and contain He+ and O+, in addition to to H+. Depending on their initial magnetic latitude and local time, and the state of the magnetosphere, they may contribute to the plasmasphere, the plasma sheet, the ring current, the warm plasma cloak etc. Depending on which path they follow in the magnetosphere, some of these ionospheric ions remain cold when they reach the two key reconnection regions: the Earth’s magnetopause and the plasma sheet in the tail. In this presentation, we will first review previous statistical works that quantify the number of cold/ionospheric ions near these two regions. Several works have attempted to quantify these populations, but they are inherently difficult to characterize due to their low energy, often below the spacecraft potential. We will also discuss the impacts they have on the magnetic reconnection process. Ionospheric ions mass-load the regions where reconnection takes place and change the characteristic Alfven speed, resulting in a smaller reconnection electric field. They also take a portion of the energy that is imparted to particles, affecting the energy budget of magnetic reconnection. Finally, they introduce new length and time scales, associated to their gyroradius and gyroperiod. We will discuss what are the implications of these impacts for the evolution of the magnetosphere – solar wind interactions.

The question of how many satellites it would take to accurately map the spatial distribution of ionospheric outflow is addressed in this study. Given an outflow spatial map, this image is then reconstructed from a limited number virtual satellite pass extractions from the original values. An assessment is conducted of the goodness of fit as a function of number of satellites in the reconstruction, placement of the satellite trajectories relative to the polar cap and auroral oval, season and universal time (i.e., dipole tilt relative to the Sun), geomagnetic activity level, and interpolation technique. It is found that the accuracy of the reconstructions increases sharply from one to a few satellites, but then improves only marginally with additional spacecraft beyond ~4. Increased dwell time of the satellite trajectories in the auroral zone improves the reconstruction, therefore a high-but-not-exactly-polar orbit is most effective for this task. Local time coverage is also an important factor, shifting the auroral zone to different locations relative to the virtual satellite orbit paths. The expansion and contraction of the polar cap and auroral zone with geomagnetic activity influences the coverage of the key outflow regions, with different optimal orbit configurations for each level of activity. Finally, it is found that reconstructing each magnetic latitude band individually produces a better fit to the original image than 2-D image reconstruction method (e.g., triangulation). A high-latitude, high-altitude constellation mission concept is presented that achieves acceptably accurate outflow reconstructions.

The energy deposition from ring current ions into the high density “cold” plasma of the ionosphere and plasmasphere is analyzed, based on a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) simulation of the 2015 October 7 storm. In this re-examination of ring current heating generating the observed O$^+$ shell in the outer plasmasphere [1], the Naval Research Laboratory (NRL) Sami3 is Also a Model of the Ionosphere (SAMI3) ionosphere/plasmasphere code [2] is used to simulate the effect of ring current heating on the ionosphere. We find that energy is deposited at altitudes as low as 100 km. We show that heating along the entirety of any given field line, both in the ionosphere and plasmasphere, contributes to the heating effect and subsequent cold O$^+$ outflows. We further show that, relative to the heating of the plasmasphere, the direct heating of the ionosphere by ring current ions produces only a small contribution to the thermal O$^+$ outflow that forms the O$^+$ shell. [1] Krall, J., J. D. Huba, and M.-C. Fok (2020), Does ring current heating generate the observed O$^+$ shell?, Geophys. Res. Lett., 47, e2020GL088419, doi:10.1029/2020GL088419 [2] Huba, J., and J. Krall (2013), Modeling the plasmasphere with SAMI3, Geophys. Res. Lett., 40, 6–10, doi:10.1029/2012GL054300 Research supported by NRL base funds and NASA.

The energy deposition from ring current ions into the high density ‘cold’ plasma of the ionosphere and plasmasphere is analyzed, based on a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) simulation of the 2015 October 7 storm. In addition, the Naval Research Laboratory (NRL) Sami3 is Also a Model of the Ionosphere (SAMI3) ionosphere/plasmasphere code is used to simulate the effect of ring current heating on the ionosphere and plasmasphere. We find that, during stormtime peaks in the Dst index, energy is deposited at altitudes as low as 100 km. Heating along the entirety of any given field line, both in the ionosphere and plasmasphere, contributes to increased temperatures in the topside ionosphere and inner magnetosphere and to subsequent cold O$^+$ outflows. However, relative to the heating of the plasmasphere, the direct heating of the ionosphere by ring current ions produces only small effects. Model-data agreement in the N$^+$/O$^+$ density ratio shows that these O$^+$ outflows are driven by thermal forcing.

Ionospheric ions (mainly H+, He+ and O+) escape from the ionosphere and populate the Earth’s magnetosphere. Their thermal energies are usually low when they first escape the ionosphere, typically a few eV to tens of eV, but are energized in their journey through the magnetosphere. The ionospheric population is variable, and it makes significant contributions to the magnetospheric mass density in key regions where magnetic reconnection is at work. Solar wind - magnetosphere coupling occurs primarily via magnetic reconnection, a key plasma process that enables transfer of mass and energy into the near-Earth space environment. Reconnection leads to the triggering of magnetospheric storms, aurorae, energetic particle precipitation and a host of other magnetospheric phenomena. Several works in the last decades have attempted to statistically quantify the amount of ionospheric plasma supplied to the magnetosphere, including the two key regions where magnetic reconnection proceeds: the dayside magnetopause and the magnetotail. Recent in-situ observations by the Magnetospheric Multiscale spacecraft and associated modelling have advanced our current understanding of how ionospheric ions alter the magnetic reconnection process at meso- and small-scales, including its onset and efficiency. This article compiles the current understanding of the ionospheric plasma supply to the magnetosphere. It reviews both the quantification of these sources and their effects on the process of magnetic reconnection. It also provides a global description of how the ionospheric ion contribution modifies the way the solar wind couples to the Earth’s magnetosphere and how these ions modify the global dynamics of the near-Earth space environment.

The escape of heavy ions from the Earth atmosphere is consequences of energization and transport mechanisms, including photoionization, electron precipitation, ion-electron-neutral chemistry and collisions. Numerous studies considered the outflow of O ions only, but ignored the observational record of outflowing N. In spite of 12% mass difference, N and O ions have different ionization potentials, ionospheric chemistry, and scale heights. We expanded the Polar Wind Outflow Model (PWOM) to include N as well as key molecular ions in the polar wind. We refer to this model expansion as the Seven Ion Polar Wind Outflow Model (7iPWOM), which involves expanded schemes for suprathermal electron impact and ion-electron-neutral chemistry and collisions. Numerical experiments, designed to probe the influence of season, as well as that of solar conditions, suggest that N is a significant ion species in the polar ionosphere and its presence largely improves the polar wind solution, as compared to observations.

While Jupiter’s gravity strongly binds the neutral atmosphere to the planet, energization in the auroral region can lead to field-aligned upward transport and escape of electrons and ions. This field-aligned transport mechanism provides a way for heavier ions like H2+ and H3+ to enter Jupiter’s magnetosphere. Formation of H3+ from H2+ occurs quickly in the collisional ionosphere, so rapid field-aligned transport of H2+ is the most likely mechanism for H2+ ions present in Jupiter’s high-latitude ionosphere and magnetosphere. We model these processes using the PWOM model for ionospheric field-aligned transport and J-GITM providing the neutral atmosphere and lower ionospheric boundary. The ionosphere is formed and heated by a combination of solar EUV flux and electorn precipitaiton. The effects of energization from electron precipitation and resonant wave heating are also accounted for. We show the energy input that is needed to produce ion escape in both the fluid and kinetic regimes, and we show the formation of ion conics in the kinetic PWOM model. We discuss what observations from JUNO are needed to allow us to constrain and test our model results.