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- Title
Observations of Circularly Polarized Magnetic Fields Associated with Electron Holes.
- Authors
Steinvall, Konrad; Graham, Daniel B.; Khotyaintsev, Yuri V.; Vaivads, Andris; Lindqvist, Per-Arne; Ergun, Robert E.; Contel, Olivier Le; Russell, Christopher T.; Torbert, Roy B.; Burch, James L.
- Abstract
Electron Holes (EHs) are nonlinear positively charged structures frequently observed in spaceplasmas. They are localized holes in electron phase-space, manifesting themselves as bipolarsolitary waves in electric field measurements. By trapping and heating electrons, EHs play animportant role in plasma dynamics. Simulations have found EHs Cherenkov-emittingelectromagnetic whistler waves in the reconnection region, which in turn was shown toincrease the rate of magnetic reconnection. Previous studies have reported magnetic fieldsignatures associated with the EHs and attributed them to the Lorentz transform of theelectric field and E × B drifting electrons generating a current and an equivalent magneticfield. We report observations of fast electromagnetic EHs made in the magnetotail reconnectionregion by the Magnetospheric Multiscale mission. We apply multi-spacecraft analysis toestimate the properties of the EHs, including the magnetic field generated by the E × Bdrifting electrons. We find that the EHs have localized, right hand polarized magnetic fieldsassociated with them, inconsistent with the aforementioned source mechanisms. Typically,these fields are either monopolar or bipolar, and are confined within the EHs. In a few caseshowever, the magnetic field takes on a more whistler wave-like character and upto four wave periods are observed. Additionally, these whistler-like fields extendoutside of the EH, forming a tail before quickly disappearing, suggesting strong wavedamping. Preliminary results show that the Cherenkov condition is satisfied. Wediscuss possible generation mechanisms of the magnetic fields associated with EHs.
- Subjects
MAGNETIC fields; ELECTRIC field strength; ELECTRONS; MAGNETIC reconnection; PLASMA dynamics
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article