Publications by authors named "Masafumi Shoji"
Using a novel wave-particle interaction analysis, we show observational evidence of energy transfer from fast magnetosonic waves (MSWs) to low-energy protons in the magnetosphere. The analysis clearly indicates that the transferred proton energies are further converted to excite electromagnetic ion cyclotron waves. Since MSWs are excited by hot ions, cross-energy coupling of ions occurs through MSWs.
View Article and Find Full Text PDFA study using Arase data gives the first observational evidence that the frequency drift of electromagnetic ion cyclotron (EMIC) waves is caused by cyclotron trapping. EMIC emissions play an important role in planetary magnetospheres, causing scattering loss of radiation belt relativistic electrons and energetic protons. EMIC waves frequently show nonlinear signatures that include frequency drift and amplitude enhancements.
View Article and Find Full Text PDFArticle Synopsis
- Bright, discrete auroral arcs in polar regions are created by magnetospheric electrons accelerated through electric fields, producing light when they collide with thermosphere atoms at around 100 km altitude.
- Recent findings indicate that these electrons can actually be accelerated from altitudes over 30,000 km, which is significantly higher than previously believed.
- The research combines data from the Arase satellite and ground-based imaging, revealing that the mechanisms behind this acceleration are still not fully understood, but they suggest a more complex interaction within the magnetosphere.