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Quasi‐adiabaticity in bifurcated current sheets
Author(s) -
Delcourt D. C.,
Malova H. V.,
Zelenyi L. M.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl025463
Subject(s) - physics , current (fluid) , current sheet , magnetic field , moment (physics) , adiabatic process , oscillation (cell signaling) , scattering , charged particle , magnetic moment , beam (structure) , condensed matter physics , computational physics , classical mechanics , magnetohydrodynamics , optics , ion , genetics , quantum mechanics , biology , thermodynamics
We examine the non‐linear dynamics of charged particles in “bifurcated” (double‐humped) current sheets. We show that, when the adiabaticity parameter κ is of the order unity, particles experience a negligible change of magnetic moment. Such a behavior contrasts with the prominent magnetic moment scattering that is achieved in single‐humped current sheets at such κ values. It resembles the quasi‐adiabatic (Speiser‐type) behaviors that is obtained at κ ≪ 1 as a result of resonance between the fast oscillation about the midplane and the slow gyromotion near this plane. We demonstrate that beams of κ ≈ 1 particles may form downstream of bifurcated current sheets, which propagate along the magnetic field lines up to high latitudes. Quasi‐adiabaticity and associated beam formation thus occur at significantly larger κ values in double‐humped current sheets than in single‐humped ones, or equivalently for lower particle energy and/or weaker field reversal.