Visualizing shear Alfve´n wave currents near the ion-Cyclotron frequency

We present measurements of the three-dimensional structure of shear Alfve´n wave currents near the ion-cyclotron frequency. The waves are launched by modulating an electron current filament with transverse size on the order of the electron collisionless skin depth. The component of the current parallel to the background magnetic field is carried by the electrons, while the cross-field current comprises both the ion-polarization and E×B currents.