dc-Magnetic-Field Generation in Unmagnetized Shear Flows

• Autor(a) principal: Grismayer, T.
• Data de Publicação: 2013
• Outros Autores: Alves, E. P., Fonseca, R. A., Silva, L. O.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://link.aps.org/doi/10.1103/PhysRevLett.111.015005; https://ciencia.iscte-iul.pt/public/pub/id/13329; http://hdl.handle.net/10071/7306

The generation of dc magnetic fields in unmagnetized electron-ion shear flows is shown to be associated to either initial thermal effects or the onset of electron-scale shear instabilities, in particular the cold Kelvin-Helmholtz instability. This mechanism, intrinsic to shear gradients on the electron scale, is described through a kinetic model that predicts the growth and the saturation of the dc field in both scenarios. The theoretical results are confirmed by multidimensional particle-in-cell simulations, demonstrating the formation of long-lived magnetic fields (t similar to 100's w(pi)(-1)) along the full longitudinal extent of the shear layer, with a typical transverse width root gamma(0)c/w(pe), reaching magnitudes eB(dc)/m(e)cw(pe) similar to beta(0) root gamma(0) for an initial sharp shear. The case of an initial smooth shear is also discussed.