Khoyloo, A. | Search NASA

NASA NTRS1991

On the discontinuity in kinetic solutions of the collisionless polar wind

The use of a Maxwellian ion velocity distribution in kinetic solutions of the collisionless polar wind regime results in a velocity distribution and associated moments that display sharp discontinuities at the boundary, which quantitatively affects the solution at high altitudes. This paper investigates the causes of this discontinuity, using both analytical and numerical approaches; it is shown that the choice of appropriate boundary conditions will eliminate the discontinuity.

Khoyloo, A.↗

NASA NTRS1985

Enhanced N(+) Sub 2 in the Shuttle Environment

Observations were made of the N2 first negative and Meinel emission bands with the Imaging Spectrometric Observatory (ISO) on Spacelab 1. These observations have revealed the presence of N2 emissions which exceed those expected on the basis of current ionospheric models by up to a factor of 10. If the emission is of terrestrial origin, large unidentified ionospheric sources of N2 ions must exist. On the other hand, if the source is local to the shuttle environment, a mechanism must be found which is capable of generating emissions of such unexpectedly large intensity. Charge exchange of ambient ionospheric O+ ions with shuttle environmental N2, followed by resonance scattering of sunlight, as a candidate were suggested. However, this model implies that a cloud of N2 gases must surround the vehicle in concentrations in excess of 10 to the 11 c.c. cm with a scale length of tens of meters. In addition, the N2 residence time must be of the order of 10 sec.

Torr, D. G.↗