Inhomogeneous plasma flows: A review of in situ observations and laboratory experiments

Abstract

Abstract. Sheared flows in near-Earth space plasmas, both magnetic-field-aligned and cross-field, contribute to a rich array of phenomena which can be simulated in the laboratory. This has led to improved knowledge of the basic processes involving velocity shear operative in space, where it is not possible to conduct detailed and repeatable experiments with control over background parameters. Depending upon the flow characteristics, shear can contribute to either growth or damping of various plasma modes or, if sufficiently strong, can itself drive instabilities. These instabilities can have significant consequences in redefining the plasma equilibrium and can lead to energization and transport. A number of laboratory experiments have been performed to investigate the detailed physics associated with inhomogeneous space plasma flows. In this work, a review of in situ observations of processes associated with sheared flows and details of complementary laboratory experimental investigations is presented.

The interplay of the collisionless non-linear thin-shell instability with the ion acoustic instability

“…Laboratory experiments thus provide essential support for the interpretation of astrophysical observations. Laboratory experiments have addressed the KelvinHelmholtz instability (Amatucci 1999) and the RayleighTaylor instability. Sharp (1984); Piriz et al (2006) provide a description of the Rayleigh-Taylor instability and references to experiments.…”

Multi-spacecraft observations of broadband waves near the lower hybrid frequency at the Earthward edge of the magnetopause

“…In addition, shear in the plasma flow usually occurs across the magnetopause. One type of generation mechanism causing broadband waves at frequencies of the order of the ion gyrofrequency depends on shear due to inhomogeneous plasma flow, either caused by changes in the flow parallel to the ambient magnetic field (Gavrishchaka et al, 1999) or by inhomogeneous perpendicular flows (Amatucci, 1999;Koepke et al, 1999;Peñano and Ganguli, 2000). Recent investigations of Freja data show that such perpendicular shear may well contribute to the generation of waves at altitudes around 2000 km in the auroral region (Hamrin et al, 2001).…”

On the Application of Cross Bispectrum and Cross Bicoherence

“…Under these conditions, there can be drift mode [1] and D'Angelo mode [24][25][26][27][28][29][30][31][32][33][34][35] as a primary modes, and zonal flows [11] and streamers [18] as a secondary mode.…”