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Spontaneous formation of current‐driven double layers in density depletions and its relevance to solitary Alfven waves
Author(s) -
Singh Nagendra
Publication year - 2002
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 - 10.1029/2001gl014033
Subject(s) - dissipation , physics , plasma , ion , electron , magnetic field , kinetic energy , double layer (biology) , wavelength , atomic physics , current density , field (mathematics) , electric field , layer (electronics) , optics , materials science , classical mechanics , mathematics , quantum mechanics , pure mathematics , composite material , thermodynamics
We demonstrate that when magnetic field‐aligned currents encounter density cavities, double layers (DLs) spontaneously form. The parallel electric field in the double layer (DL) accelerates electrons and ions to maintain the current continuity. However, such double layers are found to be transitory; their growth is initially accompanied by further deepening of a part of the cavity and the decay with subsequent refilling. The bursty acceleration of electrons and ions by the double layer provides a mechanism for the conversion of the electromagnetic energy associated with the currents into kinetic energy of the plasma. Thus the spontaneous double layer formation in plasma density cavities could be an effective dissipation mechanism for Alfven waves which carry substantial currents when they acquire sufficiently short wavelengths perpendicular to the magnetic field.