TITLE:
Empirical Patterns of High-Energy Particle Dynamics of the Van Allen Radiation Belts
AUTHORS:
Yuhan Liu
KEYWORDS:
Van Allen Radiation Belt, Relativistic Electron Dynamics, Geomagnetic Storms, Solar Cycles
JOURNAL NAME:
Advances in Aerospace Science and Technology,
Vol.5 No.2,
June
23,
2020
ABSTRACT: The Van
Allen radiation belts consist of megaelectron volt particles trapped in the
Earth’s magnetic field mainly with protons at low altitudes and
electrons at high altitudes. These concentric, donut-shaped radiation belts are constantly changing
due to a variety of physical processes caused by specific types of heliospheric
structure. The radiation poses risks for astronauts and spacecraft systems. The
understanding of these processes that operate across the universe can help with
designs of future space missions as well as the understanding of the universe.
The data gathered from the last three months of the Radiation Belt Storm Probes
mission (RBSP mission) is examined for patterns and trends in the dynamics of
the radiation belts and their relationships with solar activities. From the
data, it is shown that the patterns of the high-energy particle dynamics in the
belts follow the changes in solar activity. When the Sun’s magnetic field
weakens, cosmic rays from deep space are able to carry an increased flux of
energetic particles into the solar system. The outer belt exhibits a pattern of
electron energization during cycles lasting an average of 27 days,
corresponding to the time taken for one solar rotation. The sudden outward
shift of the belts on July 19th, 2019 was most likely caused by the shutdown of
one of the two Van Allen probes, as the relative position of the probe to the belts
changed. Two solar wind streams that arrived from August 27th to the 28th
caused the “dropout” event on August 28th, as the contact between the solar
wind streams and magnetosphere pushed the magnetosphere’s boundary and enabled
the particles outside the shifted boundary to escape into space. A positive
polarity coronal hole high speed stream (CH HSS) contributed to the intense
September electron re-energization process in the radiation belts starting on
September 1st.