NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Atmospheric helium and geomagnetic field reversals.The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.
Document ID
19730026939
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sheldon, W. R.
Kern, J. W.
(Houston, University Houston, Tex., United States)
Date Acquired
August 7, 2013
Publication Date
November 1, 1972
Publication Information
Publication: Journal of Geophysical Research
Volume: 77
Subject Category
Geophysics
Accession Number
73A11741
Funding Number(s)
CONTRACT_GRANT: F44620-71-C-0068
CONTRACT_GRANT: NGR-44-005-133
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available