A new explanation for long-duration meteor radar echoes: Persistent charged dust trains

Abstract

Meteor radar echoes persist for timescales from 3 ms to several minutes. At the low end, head echoes provide the target while underdense, diffusing charged meteor trains are associated with timescales of several tenths of a second to several tens of seconds. Longer duration trains are less well understood, and a variety of explanations have been put forth. Indeed, a variety of mechanisms probably contribute. In this paper the author shows that a dust-filled, underdense turbulent meteor train yielded a VHF meteor which lasted over 10 min. Remarkably, the train was also penetrated by a sounding rocket, which verifies the high Schmidt-number nature of the train. Although the turbulence is not yet explained, it is possible that the gravitational sedimentation of the structure provided the free energy via a shear instability of the dusty plasma. These observations further support the notion that meteor trains are associated with dust production and that the double train phenomenon is related to sedimentation of a dusty train.