Ion Composition Measurements from the RBSP/HOPE Instruments

The twin Helium Oxygen Proton Electron (HOPE) instruments are due to launch on the Radiation Belt Storm Probes (RBSP) satellites and orbit within the Earth's radiation belts. Each HOPE instrument consists of a top-hat electrostatic analyzer followed by a time of flight mass spectrometer with CEM detectors. The thermal plasma measured by the HOPE instruments contributes significantly to wave-particle interactions with high-energy radiation belt particles. This presentation will focus on an initial survey of the HOPE plasma data and instrument response. Particular attention will be paid to the penetrating radiation background rates observed as a function of geomagnetic activity and orbit location. We will also present a preliminary survey of the ion composition characteristics measured during the mission, including the variations of H+, He+, and O+ ion density with radial distance, spacecraft separation, and solar activity. In flight calibration of the instrument response and any differences between the two HOPE instruments will be presented.