A current disruption mechanism in the neutral sheet: A possible trigger for substorm expansions

摘要: A linear analysis is performed to investigate the kinetic cross-field streaming instability in Earth's magnetotail neutral sheet region. Numerical solution of dispersion equation shows that can occur under conditions expected for just prior onset substorm expansion. The excited waves are obliquely propagating whistlers with a mixed polarization lower hybrid frequency range. ensuring turbulence this lead local reduction cross-tail current causing it continue through ionosphere form wedge. expansion scenario proposed based on which relative drift between ions and electrons primarily due unmagnetized undergoing acceleration presence electric field. required field strength within range values detected region during intervals. skew time location three observed be understood basis scenario.