The Jupiter Energetic Particle Detector Instruments (JEDI) on the Juno Jupiter polar-orbiting, atmosphere-skimming, mission to Jupiter will coordinate with the several other space physics instruments on the Juno spacecraft to characterize and understand the space environment of Jupiter's polar regions, and specifically to understand the generation of Jupiter's powerful aurora. JEDI comprises 3 nearly-identical instruments and measures at minimum the energy, angle, and ion composition distributions of ions with energies from H:20 keV and O: 50 keV to > 1 MeV, and the energy and angle distribution of electrons from < 40 to > 500 keV. Each JEDI instrument uses microchannel plates (MCP) and thin foils to measure the times of flight (TOF) of incoming ions and the pulse height associated with the interaction of ions with the foils, and it uses solid state detectors (SSD's) to measure the total energy (E) of both the ions and the electrons. The MCP anodes and the SSD arrays are configured to determine the directions of arrivals of the incoming charged particles. The instruments also use fast triple coincidence and optimum shielding to suppress penetrating background radiation and incoming UV foreground. Here we describe the science objectives of JEDI, the science and measurement requirements, the challenges that the JEDI team had in meeting these requirements, the design and operation of the JEDI instruments, their calibrated performances, the JEDI inflight and ground operations, and the initial measurements of the JEDI instruments in interplanetary space following the Juno launch on 5 August 2011. Juno will begin its prime science operations, comprising 32 orbits with dimensions 1.1 × 40 RJ, in mid-2016.

The Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on the two Van Allen Probes spacecraft is the magnetosphere ring current instrument that will provide data for answering the three over-arching questions for the Van Allen Probes Program: RBSPICE will determine "how space weather creates the storm-time ring current around Earth, how that ring current supplies and supports the creation of the radiation belt populations," and how the ring current is involved in radiation belt losses. RBSPICE is a time-of-flight versus total energy instrument that measures ions over the energy range from ∼20 keV to ∼1 MeV. RBSPICE will also measure electrons over the energy range ∼25 keV to ∼1 MeV in order to provide instrument background information in the radiation belts. A description of the instrument and its data products are provided in this chapter.

This paper describes the science motivation, measurement objectives, performance requirements, detailed design, approach and implementation, and calibration of the four Hot Plasma Composition Analyzers (HPCA) for the Magnetospheric Multiscale mission. The HPCA is based entirely on electrostatic optics combining an electrostatic energy analyzer with a carbon-foil based time-of-flight analyzer. In order to fulfill mission requirements, the HPCA incorporates three unique technologies that give it very wide dynamic range capabilities essential to measuring minor ion species in the presence of extremely high proton fluxes found in the region of magnetopause reconnection. Dynamic range is controlled primarily by a novel radio frequency system analogous to an RF mass spectrometer. The RF, in combination with capabilities for high TOF event processing rates and high current micro-channel plates, ensures the dynamic range and sensitivity needed for accurate measurements of ion fluxes between ∼1 eV and 40 keV that are expected in the region of In order to calibrate the four HPCA instruments we have developed a unique ion calibration system. The system delivers a multi-species beam resolved to M/ M ∼ 100 and current densities between 0.05 and 200 pA/cm 2 with a stability of ±5 %. The entire system is controlled by a dedicated computer synchronized with the HPCA ground support equipment. This approach results not only in accurate calibration but also in a comprehensive set of coordinated instrument and auxiliary data that makes analysis straightforward and ensures archival of all relevant data.

[1] Dispersionless injections are a ubiquitous characteristic of substorms. They are defined as simultaneous enhancements in the fluxes of electrons and ions of different energies, and they are often observed near or inside geosynchronous orbit. We model dispersionless electron injections by considering the interaction of an earthward propagating electromagnetic pulse with the preexisting electron population. Such simulations have been performed previously [Li et al., 1993[Li et al., , 1998]; however, they assumed a constant propagation velocity for the transient fields. Observations have shown that substorm injections and associated magnetic signatures do not propagate at constant velocities, but rather slow down as they approach the inner magnetosphere. Between 4.5 and 6.6 R E the injection propagation speeds reach surprisingly low values, of the order of 24 km/s. Nonetheless, the injections still remain dispersionless . In our simulation we vary the pulse speed with the radial distance from the Earth to match the reported propagation speeds and demonstrate that dispersionless injections are achievable under such low propagation speeds. In particular, we simulate the dispersionless injections of 12 February 1991 measured at two radially displaced spacecraft (CRRES and LANL 1990 -095), when they were both around local midnight.