PERPENDICULAR ION HEATING BY VELOCITY-SHEAR-DRIVEN WAVES

Perpendicular ion heating resulting from velocity-shear-driven ion-cyc lotron waves has been measured for the first time. The experiment was performed in the Naval Research Laboratory's Space Physics Simulation Chamber (SPSC) under plasma conditions approaching those in the natura l space environment. Sheared cross-field flow is induced by a controll able, inhomogeneous, transverse, DC electric field (L-E similar to (1 - 2)rho(i)) created without drawing significant levels of magnetic-fie ld aligned current. Mode frequency data suggest that the most efficien t heating occurs when the Doppler shifted frequency in the ion frame i s located near a harmonic of the ion-cyclotron frequency.