The Van Allen radiation belts contain ultra-relativistic electrons that pose significant risks to Earth-orbiting spacecraft, yet the mechanisms behind their acceleration remain unclear. Here, the authors demonstrate that extremely low plasma density conditions during the 20 April 2017 geostorm enabled electron acceleration to multi-MeV energies, highlighting the critical role of plasma waves and suggesting similar processes may occur in other astrophysical environments.
- Yuri Y. Shprits
- Bernhard Haas
- Dedong Wang
