CEDAR: Modeling of Initial Temperature Relaxation and Expansion of Meteor Trails

Many meteor trails are visible to an unaided eye during shower events. Extra-terrestrial particles entering the Earth’s environment result in these trails and deposit different kind of metals/ions in the upper regions of the atmosphere. Although most of these particles have masses of a small fraction of a gram, their overall daily deposition rates are measured in thousands of tons. As the meteoroids enter the Earth’s atmosphere, they form approximately cylindrical plasma trails with considerable enhancements of electron density. There is a significant spectroscopic evidence of elevated plasma temperatures in meteor trails, exceeding several thousands of degrees kelvin. This project promotes the further progress of science by investigating the physical processes involved in temperature relaxation in these trails. These studies are expected to be applicable not only to meteor trails but any physical system involving decaying plasmas. The diffusion processes that will be studied are in operation in positive column direct current discharges. At lower ionospheric altitudes this research may bring additional knowledge about plasma inhomogeneities involved in lightning stimulated transient luminous events. A graduate student will be supported and trained under this program. This multi-disciplinary research is co-funded by the Plasma Physics program at the NSF. The innovative research aims at developing theoretical framework that employs plasma fluid equations and Monte Carlo kinetic models. The work develops from the earlier research on the electrical discharge, which has been successfully implemented for modeling of corona, and transient luminous events (TLEs). One of the primary goals of the investigation is to gain new knowledge about electron temperature relaxation in the meteor trails with a focus on diffusion dynamics. This work seeks information about the electron-neutral collision frequencies, ambipolar diffusion rates and development of gradient-drift plasma instabilities. Additionally, the numerical simulation and modeling work will facilitate: (a) electron heating and cooling rates characterization in meteor trails with altitude, (b) knowledge about the evolution of meteor trail plasma under varying geomagnetic field conditions. This has implications on the existing remote sensing techniques that employ meteor echoes for inferring temperatures and winds in the upper atmosphere. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.