The Venus ionosphere at grazing incidence of solar radiation: Transport of plasma to the night ionosphere

R. C. Whitten, B. Baldwin, W. C. Knudsen, K. L. Miller, K. Spenner

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Using a quasi-two-dimensional model of the Venus ionosphere, we calculated the ion number densities and horizontal ion bulk velocities expected for a range of solar zenith angles near the terminator (80 to 100°), and compared them with data obtained from the Pioneer Venus Orbiter retarding potential analyzer. The calculated ion bulk velocity arises entirely from the solar EUV-induced plasma pressure gradient and has a magnitude consistent with observations; ionization by suprathermal electrons is neglected in those computations. We find that while photoionization is the dominant source of ionospheric plasma for solar zenith angles less than 92°, plasma transport from the dayside is the dominant plasma source for solar zenith angles greater than 95°. We also show that the main nightside plasma peak at approximately 140 km altitude is of the F2 type (i.e., is diffusion controlled). Its altitude and shape are thus quite insensitive to the altitude of the ion source.

Original languageEnglish
Pages (from-to)261-270
Number of pages10
JournalIcarus
Volume51
Issue number2
DOIs
StatePublished - Aug 1982

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