Megavolt Parallel Potentials Arising from Double-Layer Streams in the Earth’s Outer Radiation Belt

TitleMegavolt Parallel Potentials Arising from Double-Layer Streams in the Earth’s Outer Radiation Belt
Publication TypeJournal Article
Year of Publication2013
AuthorsMozer, F, Bale, S, Bonnell, JW, Chaston, C, Roth, I, Wygant, J
JournalPhysical Review Letters
Volume111
Issue23
Date Published12/2013
ISSN0031-9007
KeywordsVan Allen Probes
AbstractHuge numbers of double layers carrying electric fields parallel to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth’s outer radiation belt. For one case with adequate high time resolution data, 7000 double layers were observed in an interval of 1 min to produce a 230 000 V net parallel potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1 000 000 volts of net parallel potential crossed the spacecraft during this time. A double layer traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, the instantaneous parallel potential along a single magnetic field line was the order of tens of kilovolts. Electrons on the field line might experience many such potential steps in their lifetimes to accelerate them to energies where they serve as the seed population for relativistic acceleration by coherent, large amplitude whistler mode waves. Because the double-layer speed of 3100  km/s is the order of the electron acoustic speed (and not the ion acoustic speed) of a 25 eV plasma, the double layers may result from a new electron acoustic mode. Acceleration mechanisms involving double layers may also be important in planetary radiation belts such as Jupiter, Saturn, Uranus, and Neptune, in the solar corona during flares, and in astrophysical objects.
URLhttp://link.aps.org/doi/10.1103/PhysRevLett.111.235002
DOI10.1103/PhysRevLett.111.235002
Short TitlePhys. Rev. Lett.


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