Energetic Water Group Ion Fluxes (Emath image >60 KEV) in a Quasiperpendicular and a Quasiparallel Shock Front as Observed Durlng the Giotto-Halley Encounter.

  1. Alan Johnstone
  1. E. Kirsch1,
  2. S. McKenna-Lawlor2,
  3. P. W. Daly1,
  4. F. M. Neubauer3,
  5. A. Coates4,
  6. A. Thompson5,
  7. D. O'Sullivan5 and
  8. K.-P. Wenzel6

Published Online: 26 MAR 2013

DOI: 10.1029/GM061p0357

Cometary Plasma Processes

Cometary Plasma Processes

How to Cite

Kirsch, E., McKenna-Lawlor, S., Daly, P. W., Neubauer, F. M., Coates, A., Thompson, A., O'Sullivan, D. and Wenzel, K.-P. (1991) Energetic Water Group Ion Fluxes (Emath image >60 KEV) in a Quasiperpendicular and a Quasiparallel Shock Front as Observed Durlng the Giotto-Halley Encounter., in Cometary Plasma Processes (ed A. Johnstone), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM061p0357

Author Information

  1. 1

    Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, FRG

  2. 2

    Space Technology, St. Patrick's College, Maynooth, Ireland

  3. 3

    Institut für Geophysik, Universität Köln, FRG

  4. 4

    Mullard Space Science Lab., University College London, Holmbury St. Mary, Dorking, Surrey, UK

  5. 5

    Institute for Advanced Studies, Dublin, Ireland

  6. 6

    Space Science Department of ESA/ESTEC, Noordwijk, NL

Publication History

  1. Published Online: 26 MAR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875900278

Online ISBN: 9781118663660



  • Comets;
  • Space plasmas;
  • Astrophysics


Energetic water group ions (E math image = 1–86 keV and E math image = 60 to >270 keV) recorded by EPA/EPONA and the JPA experiment aboard Giotto, as well as corresponding magnetic field measurements obtained, especially, at the quasiperpendicular inbound and quasiparallel outbound bow shocks of Comet Halley, were used to study particle propagation and acceleration processes in the bowshock environment. It was found that energetic particles were accelerated in association with a strong magnetosonic wave field in the foreshock, in the inbound bowshock, within the near cometosheath, as well as immediately inside and outside the broad outbound bowshock. A relatively hard spectrum was observed in the inbound foreshock (γ = 3.3). Inside the bowshock itself, the spectrum was somewhat softer (γ = 4.1), due to an increase in the fluxes in the lowest energy channels. Further acceleration of the particles took place inside the cometosheath (γ = 3.5). Similar, but somewhat steeper spectra, were observed on the outbound side. First and second order Fermi processes, as well as the transit time damping effect were most likely to have been responsible for particle acceleration at and within the bowshocks of comet Halley. The measurements also showed that more particles escaped from the outbound than from the inbound bowshock (presumably along the magnetic field vector), and that these latter particles produced a somewhat steeper energy spectrum near the bowshock.