Vlasov Simulations of Ionospheric Heating Near Upper HybridResonance

Abstract:

It is well-known that high-frequency (HF) heating of the ionosphere can excite field- aligned
density striations (FAS) in the ionospheric plasma. Furthermore, in the neighborhood of various
resonances, the pump wave can undergo parametric instabilities to produce a variety of electrostatic
and electromagnetic waves. We have used a Vlasov simulation with 1-spatial dimension, 2-velocity
dimensions, and 2-components of fields, to study the effects of ionospheric heating when the pump
frequency is in the vicinity of the upper hybrid resonance, employing parameters
currently available at ionospheric heaters such as HAARP. We have found that by seeding the
plasma with a FAS of width  ~20% of the simulation domain, ~10% depletion, and by
applying a spatially uniform HF dipole pump electric field, the pump wave gives rise to a broad
spectrum of density fluctuations as well as to upper hybrid and lower hybrid oscillating electric
fields. We also observe collisionless bulk-heating of the electrons that varies non-linearly with the
amplitude of the pump field.