Horne R. B., R. M. Thorne, Y. Y. Shprits, N. P. Meredith, S. A. Glauert, A. J. Smith, S. G. Kanekal, D. N. Baker, M. J. Engebretson, J. L. Posch, M. Spasojevic, U. S. Inan, J. S. Pickett, P. M. Decreau, (2005), Wave acceleration of electrons in the Van Allen radiation belts, Nature Communications, 437, 227–230, doi:10.1038/nature03939
Abstract
The Van Allen radiation belts1 are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth's magnetic field. Their properties vary according to solar activity2,3 and they represent a hazard to satellites and humans in space4,5. An important challenge has been to explain how the charged particles within these belts are accelerated to very high energies of several million electron volts. Here we show, on the basis of the analysis of a rare event where the outer radiation belt was depleted and then re-formed closer to the Earth6, that the long established theory of acceleration by radial diffusion is inadequate; the electrons are accelerated more effectively by electromagnetic waves at frequencies of a few kilohertz. Wave acceleration can increase the electron flux by more than three orders of magnitude over the observed timescale of one to two days, more than sufficient to explain the new radiation belt. Wave acceleration could also be important for Jupiter, Saturn and other astrophysical objects with magnetic fields.Authors (sorted by name)
Baker Decreau Engebretson Glauert Horne Inan Kanekal Meredith Pickett Posch Shprits Smith Spasojevic ThorneJournal / Conference
Nature CommunicationsAcknowledgments
We thank E. Lucek for providing fluxgate magnetometer data from the Cluster spacecraft, and N. Cornilleau-Wehrlin for an independent assessment of the wave magnetic power spectral density. This work was supported in part by the UK Natural Environment Research Council (NERC), the NSF and NASA.Bibtex
@Article{article,
AUTHOR = { Horne, Richard B. and Thorne, Richard M. and Shprits, Yuri Y. and Meredith, Nigel P. and Glauert, Sarah A. and Smith, Andy J. and Kanekal, Shrikanth G. and Baker, Daniel N. and Engebretson, Mark J. and Posch, Jennifer L. and Spasojevic, Maria and Inan, Umran S. and Pickett, Jolene S. and Decreau, Pierrette M. E. },
TITLE = {Wave acceleration of electrons in the Van Allen radiation belts},
JOURNAL = {nature},
VOLUME = {437},
YEAR = {2005},
NUMBER = {},
PAGES = {227–230},
DOI = {10.1038/nature03939},
abstract ={The Van Allen radiation belts1 are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth's magnetic field. Their properties vary according to solar activity2,3 and they represent a hazard to satellites and humans in space4,5. An important challenge has been to explain how the charged particles within these belts are accelerated to very high energies of several million electron volts. Here we show, on the basis of the analysis of a rare event where the outer radiation belt was depleted and then re-formed closer to the Earth6, that the long established theory of acceleration by radial diffusion is inadequate; the electrons are accelerated more effectively by electromagnetic waves at frequencies of a few kilohertz. Wave acceleration can increase the electron flux by more than three orders of magnitude over the observed timescale of one to two days, more than sufficient to explain the new radiation belt. Wave acceleration could also be important for Jupiter, Saturn and other astrophysical objects with magnetic fields.}
}