In plasma physics, a lower hybrid oscillation is a longitudinal oscillation of ions and electrons in a magnetized plasma.
The direction of propagation must be very nearly perpendicular to the stationary magnetic field, within about √me/mi radians.
Otherwise the electrons can move along the field lines fast enough to shield the oscillations in potential.
The lower hybrid oscillation is unusual in that the ion and electron masses play an equally important role.
Exceptions are the use of lower hybrid waves to heat and drive current in fusion plasmas, and the lower hybrid drift instability, which was thought to be an important determinant of transport in the Field-Reversed Configuration (but was not found experimentally[1]).