According to new studies, electrons in the Van Allen radiation belts are locally heated to extremely high energies.
The earth’s magnetic field traps high-energy particles. When the first satellites were launched, scientists led by James Van Allen unexpectedly discovered the high-energy particle radiation regions that were later named after the discoverer Van Allen Radiation Belts. When visualized, they look like two donut-shaped regions that encompass our planet.
A new study by researchers at the GFZ now shows that electrons in the radiation belt can be accelerated locally to very high speeds. The study shows that the magnetosphere acts as a very efficient particle accelerator, accelerating electrons to so-called ultra-relativistic energies. The study by Hayley Allison, postdoctoral fellow at GFZ Potsdam, and Yuri Shprits from GFZ and professor at the University of Potsdam, was published in Communication with nature.
To better understand the origin of the Van Allen Belts in 2012 NASA launched the Van Allen Probes twin spacecraft to traverse this harshest environment and take detailed measurements in this dangerous region. The measurements included a whole series of particles moving at different speeds and in different directions plasma Waves. Plasma waves are similar to the waves we see on the surface of the water, but they are invisible to the naked eye. They can be compared to waves in an electric and magnetic field.
Recent observations have shown that the energy of the electrons in the belt can rise to so-called ultra-relativistic energies. These electrons with temperatures over 100 billion degrees Fahrenheit, move so fast that their kinetic energy is much higher than their resting energy, which is given by Einstein’s famous E = mc2 formula. They are so fast that the flow of time for these particles slows significantly.
Scientists were surprised to find these ultra-relativistic electrons, assuming that such high energies can only be achieved through a combination of two processes: the transport of particles from the outer regions of the magnetosphere inward, which accelerates them; and a local acceleration of particles by plasma waves.
However, the new study shows that electrons reach such incredible energies locally in the heart of the belts by getting all of that energy from plasma waves. This process proves to be extremely efficient. The unexpected discovery of how particles accelerate to ultra-relativistic energies in near-Earth space may help scientists understand the basic acceleration processes occurring on the sun, near outer planets, and even in the far corners of the universe where the Space explored can not reach.
Reference: “Local heating of radiation belt electrons to ultra-relativistic energies” by Hayley Allison and Yuri Shprits, September 10, 2020, Communication with nature.
DOI: 10.1038 / s41467-020-18053-z
