Software-type Wave–Particle Interaction Analyzer on board the Arase satellite

Abstract

We describe the principles of the Wave-Particle Interaction Analyzer (WPIA) and the implementation of the Softwaretype WPIA (S-WPIA) on the Arase satellite. The WPIA is a new type of instrument for the direct and quantitative measurement of wave-particle interactions. The S-WPIA is installed on the Arase satellite as a software function running on the mission data processor. The S-WPIA on board the Arase satellite uses an electromagnetic field waveform that is measured by the waveform capture receiver of the plasma wave experiment (PWE), and the velocity vectors of electrons detected by the medium-energy particle experiment-electron analyzer (MEP-e), the high-energy electron experiment (HEP), and the extremely high-energy electron experiment (XEP). The prime objective of the S-WPIA is to measure the energy exchange between whistler-mode chorus emissions and energetic electrons in the inner magnetosphere. It is essential for the S-WPIA to synchronize instruments to a relative time accuracy better than the time period of the plasma wave oscillations. Since the typical frequency of chorus emissions in the inner magnetosphere is a few kHz, a relative time accuracy of better than 10 μs is required in order to measure the relative phase angle between the wave and velocity vectors. In the Arase satellite, a dedicated system has been developed to realize the time resolution required for inter-instrument communication. Here, both the time index distributed over all instruments through the satellite system and an S-WPIA clock signal are used, that are distributed from the PWE to the MEP-e, HEP, and XEP through a direct line, for the synchronization of instruments within a relative time accuracy of a few μs. We also estimate the number of particles required to obtain statistically significant results with the S-WPIA and the expected accumulation time by referring to the specifications of the MEP-e and assuming a count rate for each detector.Keywords: Radiation belts, Magnetosphere, Whistler-mode chorus, Wave-particle interactions © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

A Systematic Study in Characteristics of Lower Band Rising‐Tone Chorus Elements

“…The relationships suggested in the present study should be examined by comparing with other in situ observations, such as those from the Arase satellite in the Exploration of energization and Radiation in Geospace (ERG) project (Miyoshi et al, ), which has orbits in a relatively inner portion of the magnetosphere than the THEMIS probes. The Arase satellite is capable to observe chorus elements (Kasaba et al, ; Kasahara et al, ; Matsuda et al, ), the number density of cold plasma derived from both the upper hybrid resonance frequency (Kumamoto et al, ) and the local magnetic field intensity (Matsuoka et al, ), energetic electrons that provide free energy to chorus generating (Kasahara et al, ; Kazama et al, ), and energy exchanges between waves and particles (Hikishima et al, ; Katoh et al, ). A comprehensive study in Arase's data in the future will help us find important clues in understanding the characteristics of chorus elements revealed by the present study.…”

The ERG Science Center

“…The plasma wave experiment (PWE)/waveform capture (WFC) (Kasahara et al 2018b;Matsuda et al 2018) and Software-type wave -particle interaction analyzer (S-WPIA) (Katoh et al 2017;Hikishima et al 2018) have intermittently performed waveform observations along a satellite orbit. Waveform data of plasma waves are important for studying wave-particle interactions through detailed comparisons with the groundbased optical and wave observations (Shiokawa et al 2017).…”

Theory, modeling, and integrated studies in the Arase (ERG) project

“…The results of integrated studies can also be used in the operation planning of the Arase satellite, particularly for the observation planning of software-type wave-particle interaction analyzer (S-WPIA) on board the Arase satellite (Katoh et al 2018a;Hikishima et al, submitted to Earth, Planets and Space). S-WPIA challenges the direct measurement of wave-particle interactions between chorus emissions and relativistic electrons in the inner magnetosphere.…”