Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) Revisited: In-Flight Calibrations, Lessons Learned and Scientific Advances.

The Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on both the Van Allen Probes spacecraft is a time-of-flight versus total energy instrument that provided ion composition data over the ring current energy (∼7 keV to ∼1 MeV), and electrons over the energy range ∼25 keV to ∼1 MeV throughout the duration of the mission (2012 - 2019). In this paper we present instrument calibrations, implemented after the Van Allen Probes mission was launched. In particular, we discuss updated rate dependent corrections, possible contamination by "accidentals" rates, and caveats concerning the use of certain products. We also provide a summary of the major advances in ring current science, obtained from RBSPICE observations, and their implications for the future of inner magnetosphere exploration.

On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles.

The ionosphere is one of the important sources for magnetospheric plasma, particularly for heavy ions with low charge states. We investigate the effect of solar illumination on the number flux of ion outflow using data obtained by the Fast Auroral SnapshoT (FAST) satellite at 3000-4150 km altitude from 7 January 1998 to 5 February 1999. We derive empirical formulas between energy inputs and outflowing ion number fluxes for various solar zenith angle ranges. We found that the outflowing ion number flux under sunlit conditions increases more steeply with increasing electron density in the loss cone or with increasing precipitating electron density (> 50 eV), compared to the ion flux under dark conditions. Under ionospheric dark conditions, weak electron precipitation can drive ion outflow with small averaged fluxes (~ 107 cm-2 s-1). The slopes of relations between the Poynting fluxes and outflowing ion number fluxes show no clear dependence on the solar zenith angle. Intense ion outflow events (> 108 cm-2 s-1) occur mostly under sunlit conditions (solar zenith angle < 90°). Thus, it is presumably difficult to drive intense ion outflows under dark conditions, because of a lack of the solar illumination (low ionospheric density and/or small scale height owing to low plasma temperature).

Discovery of proton hill in the phase space during interactions between ions and electromagnetic ion cyclotron waves.

A study using Arase data gives the first observational evidence that the frequency drift of electromagnetic ion cyclotron (EMIC) waves is caused by cyclotron trapping. EMIC emissions play an important role in planetary magnetospheres, causing scattering loss of radiation belt relativistic electrons and energetic protons. EMIC waves frequently show nonlinear signatures that include frequency drift and amplitude enhancements. While nonlinear growth theory has suggested that the frequency change is caused by nonlinear resonant currents owing to cyclotron trapping of the particles, observational evidence for this has been elusive. We survey the wave data observed by Arase from March, 2017 to September 2019, and find the best falling tone emission event, one detected on 11th November, 2017, for the wave particle interaction analysis. Here, we show for the first time direct evidence of the formation of a proton hill in phase space indicating cyclotron trapping. The associated resonance currents and the wave growth of a falling tone EMIC wave are observed coincident with the hill, as theoretically predicted.