Spacecraft Interactions Branch, Phillips Laboratory, Hanscom AFB, MA 01731, U.S.A.
Radex, Inc., Bedford, MA 01730, U.S.A.
Abstract:
The efficiency with which critical ionization velocity (CIV) discharges can be generated in space experiments is affected by the altitude at which the experiments are conducted. At around 500 km higher plasma density enhances plasma lower hybrid instability, momentum coupling efficiency, and charge exchange which is needed for seed ionization. At higher altitudes where atomic hydrogen and helium become the dominant ambient neutral species, the conditions for CIV discharge may improve considerably because less energy is lost to atmospheric ionization, even though the ambient density is reduced.