Virginia TechGanguli, GurudasSlinker, S.Gavrishchaka, V.Scales, Wayne A.2014-04-092014-04-092002-05-01Ganguli, G.; Slinker, S.; Gavrishchaka, V.; Scales, W., "low frequency oscillations in a plasma with spatially variable field-aligned flow," Phys. Plasmas 9, 2321 (2002); http://dx.doi.org/10.1063/1.14451811070-664Xhttp://hdl.handle.net/10919/47056The effects of a transverse gradient in the plasma flow velocity parallel to the ambient magnetic field are analyzed. A transverse velocity gradient in the parallel ion flow, even in small magnitude, can increase the parallel phase speed of the ion-acoustic waves sufficiently to reduce ion Landau damping. This results in a significantly lower threshold current for the current driven ion acoustic instability. Ion flow gradients can also give rise to a new class of ion cyclotron waves via inverse cyclotron damping. A broadband wave spectrum with multiple cyclotron harmonics is possible. A combination of the multiple cyclotron harmonic waves can result in spiky electric field structures with their peaks separated by an ion cyclotron period. A spatial gradient in the parallel electron flow is also considered but it is found to play a minimal role in the low frequency regime. Relevance of these to natural plasma environments is discussed. (C) 2002 American Institute of Physics.application/pdfenIn CopyrightIon-cyclotron instabilityTransverse electric-fieldsVelocity shearMagnetic fluidsElectrostatic-wavesAcoustic wavesAuroral regionSolar-windIonosphereCurrentsArticle - Refereedhttp://scitation.aip.org/content/aip/journal/pop/9/5/10.1063/1.1445181https://doi.org/10.1063/1.1445181