Excitation of ion waves by charged dust beams in ionospheric aerosol release experiments*

Ion waves may be excited by charged dust beams streaming across or along the geomagnetic field in the ionosphere during aerosol release experiments. The injection speed of the dust and gas is comparable to or larger than the ion thermal speed in the background plasma. The dust grains get charged by plasma collection from the ambient ionosphere, and can thus act as a heavy charged particle beam that excites instabilities in the background plasma. Wave frequencies larger than the ion gyrofrequency are considered, and collisions with neutrals are included. The theory is applied to relatively early times scales on the order of 0.1 -- 1 seconds in the dust-gas cloud expansion. Further issues will be explored, including the effects of photoemission on dust charging under daytime conditions, and possible instabilities associated with the generation of ion beams due to charge exchange of the exhaust neutrals with ambient ions.