The Farley-Buneman Instability

An experimental investigation of the nonlinear Farley-Buneman Instability

Objective: To measure the linear and nonlinear behavior of instabilities driven by a perpendicularly propagating electron beam. Both collisional and noncollisional methods for exciting the waves will be investigated and compared.

Significance: Dust left behind in meteor trails in the E region of the ionosphere scavenge the electrons along the path, causing a cross-path electric field and exciting Farley-Buneman waves. At large amplitude, the perturbed electrons and ions undergo temperature oscillations which can drive secondary instabilities. This nonlinear process is believed to be required for agreement between theory and experiment.

Long Range Goal: To provide experimental evidence for such secondary instabilities.

Collaborators: Paul Miller, Josh Miller, M. Oppenheim (Boston Univ.), Y. Dimant (Cornell), Mark Koepke

Once the Farley-Buneman instability develops into large-amplitude waves, particle temperature may become modulated as friction heats/cools particles periodically that are forced through the neutral-particle population by the ac electric field. This results in altering propagation direction and phase speed, better explaining the observed back-scattered radar signatures in meteor trails detected in the E-region ionosphere.