ALBERT

Description: The Compact Dual Ion Composition Experiment – CoDICE – simultaneously provides high quality plasma and energetic ion composition measurements over six decades in energy in a wide variety of space plasma environments. CoDICE measures two critical ion populations in space plasmas: 1) Elemental and charge state composition, and 3D velocity distributions of 〈10 eV/q–40 keV/q plasma ions; and 2) Elemental composition, energy spectra and angular distributions of ∼30 keV–〉10 MeV energetic ions. CoDICE uses a novel, integrated, common time-of-flight subsystem that provides several advantages over the commonly used separate plasma and energetic ion sensors currently flying on several space missions. These advantages include reduced mass and volume compared to two separate instruments, reduced shielding in high radiation environments, and simplified spacecraft interface and accommodation requirements. This paper describes the operation principles, electro-optic simulation results, and applies the CoDICE concept for measuring plasma and energetic ion populations in Jupiter's magnetosphere.

Description: The Solar Orbiter mission seeks to make connections between the physical processes occurring at the Sun or in the solar corona and the nature of the solar wind created by those processes which is subsequently observed at the spacecraft. The mission also targets physical processes occurring in the solar wind itself during its journey from its source to the spacecraft. To meet the specific mission science goals, Solar Orbiter will be equipped with both remote-sensing and in-situ instruments which will make unprecedented measurements of the solar atmosphere and the inner heliosphere. A crucial set of measurements will be provided by the Solar Wind Analyser (SWA) suite of instruments. This suite consists of an Electron Analyser System (SWA-EAS), a Proton and Alpha particle Sensor (SWA-PAS), and a Heavy Ion Sensor (SWA-HIS) which are jointly served by a central control and data processing unit (SWA-DPU). Together these sensors will measure and categorise the vast majority of thermal and suprathermal ions and electrons in the solar wind and determine the abundances and charge states of the heavy ion populations. The three sensors in the SWA suite are each based on the top hat electrostatic analyser concept, which has been deployed on numerous space plasma missions. The SWA-EAS uses two such heads, each of which have 360° azimuth acceptance angles and ±45° aperture deflection plates. Together these two sensors, which are mounted on the end of the boom, will cover a full sky field-of-view (FoV) (except for blockages by the spacecraft and its appendages) and measure the full 3D velocity distribution function (VDF) of solar wind electrons in the energy range of a few eV to ∼5 keV. The SWA-PAS instrument also uses an electrostatic analyser with a more confined FoV (−24° to +42° × ±22.5° around the expected solar wind arrival direction), which nevertheless is capable of measuring the full 3D VDF of the protons and alpha particles arriving at the instrument in the energy range from 200 eV/q to 20 keV/e. Finally, SWA-HIS measures the composition and 3D VDFs of heavy ions in the bulk solar wind as well as those of the major constituents in the suprathermal energy range and those of pick-up ions. The sensor resolves the full 3D VDFs of the prominent heavy ions at a resolution of 5 min in normal mode and 30 s in burst mode. Additionally, SWA-HIS measures 3D VDFs of alpha particles at a 4 s resolution in burst mode. Measurements are over a FoV of −33° to +66° × ±20° around the expected solar wind arrival direction and at energies up to 80 keV/e. The mass resolution (m/Δm) is 〉 5. This paper describes how the three SWA scientific sensors, as delivered to the spacecraft, meet or exceed the performance requirements originally set out to achieve the mission’s science goals. We describe the motivation and specific requirements for each of the three sensors within the SWA suite, their expected science results, their main characteristics, and their operation through the central SWA-DPU. We describe the combined data products that we expect to return from the suite and provide to the Solar Orbiter Archive for use in scientific analyses by members of the wider solar and heliospheric communities. These unique data products will help reveal the nature of the solar wind as a function of both heliocentric distance and solar latitude. Indeed, SWA-HIS measurements of solar wind composition will be the first such measurements made in the inner heliosphere. The SWA data are crucial to efforts to link the in situ measurements of the solar wind made at the spacecraft with remote observations of candidate source regions. This is a novel aspect of the mission which will lead to significant advances in our understanding of the mechanisms accelerating and heating the solar wind, driving eruptions and other transient phenomena on the Sun, and controlling the injection, acceleration, and transport of the energetic particles in the heliosphere.

Description: Saturn has a sufficiently strong dipole magnetic field to trap high-energy charged particles and form radiation belts, which have been observed outside its rings. Whether stable radiation belts exist near the planet and inward of the rings was previously unknown. The Cassini spacecraft’s Magnetosphere Imaging Instrument obtained measurements of a radiation belt that lies just above Saturn’s dense atmosphere and is decoupled from the rest of the magnetosphere by the planet’s A- to C-rings. The belt extends across the D-ring and comprises protons produced through cosmic ray albedo neutron decay and multiple charge-exchange reactions. These protons are lost to atmospheric neutrals and D-ring dust. Strong proton depletions that map onto features on the D-ring indicate a highly structured and diverse dust environment near Saturn.

Description: Recent studies have utilized different charge states of oxygen ions as a tracer for the origins of plasma populations in the magnetosphere of Earth, using O + as an indicator of ionospheric-originating plasma and O 6+ as an indicator of solar wind-originating plasma. These studies have correlated enhancements in O 6+ to various solar wind and geomagnetic conditions to characterize the dominant solar wind injection mechanisms into the magnetosphere, but did not include analysis of the temporal evolution of these ions. A 6 th -order Fourier expansion model based empirically on a superposed epoch analysis of geomagnetic storms observed by Polar is presented in this study to provide insight into the evolution of both ionospheric-originating and solar wind-originating plasma throughout geomagnetic storms. At high energies (~200 keV) the flux of O + and O 6+ are seen to become comparable in the outer magnetosphere. Moreover, while the density of O + is far higher than O 6+ , the two charge states have comparable pressures in the outer magnetosphere. The temperature of O 6+ is generally higher than that of O + , because the O 6+ is injected from pre-heated magnetosheath populations before undergoing further heating once in the magnetosphere. A comparison between the model results with O + observations from the Magnetospheric Multiscale (MMS) mission and the Van Allen Probes provides a validation of the model. In general, this empirical model agrees qualitatively well with the trends seen in both datasets. Quantitatively, the modeled density, pressure, and temperature almost always agree within a factor of at most 10, 5, and 2, respectively.

Description: We present Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of Marsward and tailward fluxes of suprathermal (〉25 eV) ions in the near-Mars (∼1–1.5 Mars radii downstream) magnetotail. Statistical results show that the Marsward proton flux and magnetic field draping pattern are well organized by the upstream motional electric field direction. We observe both significant Marsward proton fluxes and tightly wrapped magnetic field lines in the hemisphere pointed in the opposite direction to the upstream electric field. These characteristics are very similar to those observed at Venus. On the other hand, the net flux of oxygen ions points tailward on average in the Martian tail, while net Venusward flows of oxygen ions were observed frequently in the same hemisphere at Venus. The mechanism by which the Marsward proton flux is produced in the presence of tailward oxygen ion flux remains unclear.

Description: Understanding the sources and subsequent evolution of plasma in a magnetosphere holds intrinsic importance for magnetospheric dynamics. Previous studies have investigated the balance of ionospheric-originating heavy ions (low charge state) from those of solar wind origin (high charge state) in the magnetosphere of Earth. These studies have suggested a variety of entry mechanisms for solar wind ions to penetrate into the magnetosphere. Following from recently published distributions for oxygen charge states observed by the Polar spacecraft, this paper investigates oxygen charge state flux distributions versus L shell and magnetic latitude (MLAT). By showing these distributions in this frame, and binning by various proxies for magnetospheric dynamics ( D S T , A E , V S W ∗ B Z , P d y n ), insight has been gained into the underlying physics at play for oxygen injection. Ionospheric-originating oxygen is observed to depend predominantly on D S T , whereas solar wind-originating oxygen is observed to have a strong dependence on solar wind dynamic pressure ( P d y n ) at the flanks and on V S W ∗ B Z at the dayside. This suggests that both Kelvin-Helmholtz instabilities and reconnection play major roles in solar wind ion penetration into a magnetosphere. Additionally, the near-Earth magnetotail reconnection site does not seem to be a major injection site of solar wind-originating plasma in the 1 to 200 keV/e energy range.