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Relationship between wave energy and free energy from pickup ions in the Comet Halley environmentThe free energy available from the implanted heavy ion population at Comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. Upstream and downstream free energies are obtained separately for the conditions observed along the Giotto spacecraft trajectory. The results indicate that the waves are mostly upstream propagating in the solar wind frame. The total free energy density always exceeds the measured wave energy density because, as expected in the nonlinear process of ion scattering, the available energy is not all immediately released. An estimate of the amount which has been released can be obtained from the measured oxygen ion distributions and again it exceeds that observed. The theoretical analysis is extended to calculate the k spectrum of the cometary-ion-generated turbulence.
Document ID
Document Type
Reprint (Version printed in journal)
Huddleston, D. E. (NASA Headquarters Washington, DC United States)
Johnstone, A. D. (London, University College, Dorking, United Kingdom)
Date Acquired
August 15, 2013
Publication Date
August 1, 1992
Publication Information
Publication: Journal of Geophysical Research
Volume: 97
Issue: A8, A
ISSN: 0148-0227
Subject Category
Distribution Limits