Search Publications

Comparison of observed and calculated implanted ion distributions outside Comet Halley's bow shock

Coates, A. J.; Neugebauer, M.; Gombosi, T. I. +2 more

This paper compares calculated and measured energy spectra of implanted H⁺ and O⁺ ions on the assumption that the pickup geometry is quasi-parallel and about 1% of the waves generated by the cometary pickup process propagate backward (toward the comet). The model provides a good description of the implanted O⁺ and …

Quasi-linear pitch angle and energy diffusion of pickup ions near comet Halley

Coates, A. J.; Neubauer, F. M.; Johnstone, A. D. +1 more

The process of ion pickup in the environment of Halley's comet is studied in order to see if velocity diffusion driven by the observed level of turbulence can explain the observed development of the implanted ion distribution. The theoretical description used is based on a quasi-linear approach and considers the implantation and transport of comet…

The composition and plasma signature of a large dust impact on the Giotto spacecraft

Coates, A. J.; Balsiger, H.; Neubauer, F. M. +6 more

At about 14,800 km from the comet Halley nucleus, on the inbound leg, at least six of the sensors onboard the Giotto spacecraft observed an unusual, brief (~30 to 500 ms) event: The ion mass spectrometer data show a brief flow of energetic (up to several hundred electron volts) plasma consisting of protons, water group, and heavier ions. The Johns…