Localized lower hybrid acceleration of ionospheric plasma

We report observations of the transverse acceleration of ions in localized regions of intense lower hybrid waves at altitudes near 1000 km in the auroral ionoshpere. The acceleration regions are thin filaments with dimensions across geomagnetic field lines of about 50--100 m corresponding to 5--10 thermal ion gyroradii or one hot ion gyroradius. Within the acceleration region lower hybrid waves reach peak-to-peak amplitudes of 100--300 mV/m and ions are accelerated transversely with characteristic energies of the order of 10 eV. These observations are consistent with theories of lower hybrid wave collapse.