Simultaneous, co-located parallel-flow shear and perpendicular-flow shear in low-temperature, ionospheric-plasma relevant laboratory plasma

Shear in plasma flow can lead to either suppression or enhancement of plasma fluctuations, as illustrated by a variety of laboratory experiments. The plasma equilibrium conditions associated with flow shear are discussed in terms of test-particle simulations and experimental observations. The demonstration of producing and controlling simultaneous, co-located shears in both parallel flow and perpendicular flow are reported. Ion-cyclotron and lower-hybrid waves associated with this two-dimensional flow-shear configuration are observed. It is concluded that laser-induced fluorescence measurements of ion-velocity profiles both make it possible to document shear flow and aid significantly the interpretation of kinetic effects that influence the mechanisms invoked to explain flow-shear-driven plasma fluctuations