Plasma Fluctuations and Large-Scale Mixing Near Comet Giacobini-Zinner

  1. Thomas J. Birmingham and
  2. Alexander J. Dessler
  1. D.N. Baker,
  2. W.C. Feldman,
  3. S.P. Gary,
  4. D.J. McComas and
  5. J. Middleditch

Published Online: 19 MAR 2013

DOI: 10.1029/SP027p0117

Comet Encounters

Comet Encounters

How to Cite

Baker, D.N., Feldman, W.C., Gary, S.P., McComas, D.J. and Middleditch, J. (1988) Plasma Fluctuations and Large-Scale Mixing Near Comet Giacobini-Zinner, in Comet Encounters (eds T. J. Birmingham and A. J. Dessler), American Geophysical Union, Washington, D.C.. doi: 10.1029/SP027p0117

Author Information

  1. Los Alamos National Laboratory, Los Alamos, NM 87545

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875902395

Online ISBN: 9781118668757



  • Cometary interaction;
  • Comet Giacobini-Zinner;
  • Density fluctuation;
  • Electron plasma;
  • International Cometary Explorer (ICE) mission;
  • Plasma fluctuations;
  • Power spectral density (PSD)


Low-pass filtered data from the ICE electron spectrometer are used to examine relationships between plasma densities, flow speeds, flow directions, and temperatures at distances within ∼105 km of the Comet Giacobini-Zinner nucleus. The sheath/transition region is characterized by electron temperatures of ∼4×105K but with flow speeds and densities that commonly vary by factors of three or more. The largest amplitude density spikes often have significant flow changes associated with them, but a consistent pattern (as might accompany cometary rays, for example) is not found. Power spectral analyses in and near the sheath/transition regions show that density fluctuation levels are enhanced at all detectable frequencies from ∼0 to 21 mHz, consistent with strong density fluctuations on all measured time scales. Marginally significant power peaks are seen at periods of ∼4 min on the inbound pass and at ∼2 min on the outbound pass. Mechanisms such as amplification of convected ion pick-up waves and cometary rays for producing the large plasma variations are discussed. It is also suggested that a Rayleigh-Taylor driven mixing mechanism at a mass loading boundary ∼105 km from the nucleus may be operative.