Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer for the Radiation Belt Storm Probes Mission

Abstract

The HOPE mass spectrometer of the Radiation Belt Storm Probes (RBSP) mission (renamed the Van Allen Probes) is designed to measure the in situ plasma ion and electron fluxes over 4π sr at each RBSP spacecraft within the terrestrial radiation belts. The scientific goal is to understand the underlying physical processes that govern the radiation belt structure and dynamics. Spectral measurements for both ions and electrons are acquired over 1 eV to 50 keV in 36 log-spaced steps at an energy resolution E FWHM /E ≈ 15 %. The dominant ion species (H + , He + , and O + ) of the magnetosphere are identified using foil-based time-of-flight (TOF) mass spectrometry with channel electron multiplier (CEM) detectors. Angular measurements are derived using five polar pixels coplanar with the spacecraft spin axis, and up to 16 azimuthal bins are acquired for each polar pixel over time as the spacecraft spins. Ion and electron measurements are acquired on alternate spacecraft spins. HOPE incorporates several new methods to minimize and monitor the background induced by penetrating particles in the harsh environment of the radiation belts. The absolute efficiencies of detection are continuously monitored, enabling precise, quantitative measurements of electron and ion fluxes and ion species abundances throughout the mission. We describe

The relationship between the macroscopic state of electrons and the properties of chorus waves observed by the Van Allen Probes

“…They have an orbital period of ∼9 h, a perigee at ∼1.1 R E and an apogee at ∼5.8 R E [Mauk et al, 2014]. Based on these chorus wave events, we have used the level 3 unidirectional differential particle flux measurements from both the Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer [Funsten et al, 2013] of the Energetic particle, Composition, and Thermal plasma (ECT) Suite [Spence et al, 2013] and the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) [Mitchell et al, 2013] to calculate plasma parameters such as electron parallel temperature T ∥e and perpendicular temperature T ⟂e , and electron ∥e . In this study, we have used the wave data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) [Kletzing et al, 2014] which measures both the DC magnetic field and the magnetic fluctuations from 10 Hz up to 12 kHz on board Van Allen probes A and B to identify chorus wave events from October 2012 to December 2015 using the same data set as Li et al [2016].…”

The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

“…The orbital period is~9 h. The spacecraft spin period is~12 s, with the spin axis pointing approximately in the solar direction [Mauk et al, 2012]. As components of the RBSP-Energetic Particle Composition and Thermal Plasma (ECT) suite [Spence et al, 2013], the HOPE instrument [Funsten et al, 2013] ) with energies of~1 eV-50 keV, while MagEIS [Blake et al, 2013] provides total ion measurement (no ion composition discrimination) in the energy range of~60 keV-1 MeV. Based on previous studies, during quiet times and small geomagnetic storms, protons contribute the majority of ring current energy density [e.g., Krimigis et al, 1985;Daglis et al, 1993].…”

Intense duskside lower band chorus waves observed by Van Allen Probes: Generation and potential acceleration effect on radiation belt electrons

“…In this letter, we report an event of intense duskside lower band chorus waves observed by the Van Allen Radiation Belt Storm Probes (RBSP) [Mauk et al, 2013] Figure 1 gives an overview of this intense duskside chorus event recorded by the RBSP-B satellite on 2 October 2013. The wave magnetic power spectral distribution in the frequency range of 0.1 to 5.0 kHz was observed by the Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) Waves instrument [Kletzing et al, 2013]; the suprathermal electron pitch angle distribution was collected by the Helium Oxygen Proton Electron (HOPE) [Funsten et al, 2013] and Magnetic Electron Ion Spectrometer (MagEIS) [Blake et al, 2013] instruments of the Energetic Particle, Composition, and Thermal Plasma (ECT) suite [Spence et al, 2013]; the magnetic field and electric field were detected by the EMFISIS Magnetometer and Electric Fields and Waves (EFW) [Wygant et al, 2013] instruments. During the time range from 04:50 UT to 06:00 UT, the RBSP-B satellite was located around the duskside low-latitude region outside of L = 5.…”