Experimental investigation of the nonlinear spatio-temporally stationary inertial Alfven wave*

The stationary inertial Alfven wave is a non-fluctuating, non-traveling, spatially periodic pattern in electromagnetic field and fluid quantities [Knudsen, J. Geophys. Res. 101, 10761, (1996)]. This nonlinear Alfvenic perturbation is supported by the simultaneous presence of magnetic-field-aligned current and cross-magnetic-field plasma flow. In the upgraded Large Plasma Device (LAPD) at UCLA [Gekelman et al., Rev. Sci. Instrum. 87, 025105 (2016)], experiments were performed in helium plasma to verify the theoretically predicted [Finnegan et al., Nonlin. Processes Geophys., 15, 957 (2008)] patterns in ion density and electron energy. A variety of electrodes (e.g., multi-disk, mesh, emissive, etc.) provided experimental control of the azimuthal plasma flow across an off-axis localized current channel having electron drift directed either parallel or antiparallel to the background axial magnetic field. In this poster, theoretical predictions and experimental measurements are compared for various cases.