![]() Figure 2 summarizes the transport/acceleration mechanisms in the L vs. The free energy for generating whistler mode waves is the temperature anisotropy of electrons of tens of keV, and subsequent wave-particle interactions including nonlinear process will generate chorus waves that accelerate relativistic electrons of the outer belt. It has been suggested that resonant interactions by whistler mode waves cause relativistic electron acceleration inside the radiation belts. Another candidate is termed the internal acceleration process. The ULF (Ultra-Low Frequency) pulsations called "Pc5" with periods of a few minutes have been considered a main driver for the radial transportation via drift-resonance with electrons. This process has been modeled as the stochastic radial diffusion process, which is a fundamental transportation mode of energetic electrons. In this process, the energy of electrons increases due to the conservation of their first and second adiabatic invariants, when electrons are transported from the plasma sheet to the inner magnetosphere. One is the external source process via quasi-adiabatic acceleration. Two possible mechanisms have been proposed for the acceleration of relativistic electrons. During huge magnetic storms, the radiation belts are largely deformed, and large flux enhancement are observed in the slot region and the inner belt. In space storms, the outer belt electrons decrease significantly during the main phase, then recover to, and often increase over, pre-storm levels during the recovery phase. These energetic highly charged particles cause a variety of problems such as the malfunctioning of the computers on satellites and undesirable charging of equipment, or radiation exposure to astronauts. The region of outer space near the Earth, known as geospace, is populated by a large volume of very high-energy electrons and ions trapped in the Van Allen radiation belts by the Earth's magnetic field. Note: SPRINT (Small space science Platform for Rapid INvestigation and Test) is the name of a minisatellite platform of JAXA/ISAS.įigure 1: Schematic picture of the SPRINT-B/ERG exploration region (image credit: JAXA/ISAS)Ĭomprehensive observations for plasma/particles, fields and waves near the magnetic equator are important for understanding the cross energy coupling for relativistic electron accelerations and dynamics of space storms (Figure 1). Moreover, the science coordination team and the project science center work for the project management. ![]() The ERG project consists of not only the SPRINT-B/ERG satellite team, but also of a ground network team and of an integrated data analysis team. A newly developed wave-particle interaction analyzer will also be installed on the spacecraft. The ERG satellite will observe directly the plasma/particle distribution for wide energy range and the electric/magnetic field for the wide frequency range, which are essential to understand the particle acceleration. Moreover, the forecast of the large flux enhancement of the relativistic electrons is one of the key issues of the modern space weather study. The relativistic electrons of the Van Allen radiation belts often cause satellite malfunctions and anomaly, and therefore it is important to understand the flux loss and enhancement mechanisms. The aim is to elucidate acceleration and loss mechanisms of relativistic particles in the inner magnetosphere during space storms. Spacecraft Launch Mission Status Sensor Complement ReferencesĮRG is a Japanese (JAXA/ISAS) STP (Solar Terrestrial Physics) minisatellite mission into geospace focused on the formation of the radiation belts associated with magnetic storms. Gravity, Magnetic and Geodynamic measurementsĮlectric Field (vector), ULF-HF Electromagnetic WavesĮRG (Exploration of energization and Radiation in Geospace) /Arase
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