Experimental plasma parameters at comet Halley
Amata, E.; Formisano, V.; Wilken, B.; Bavassano-Cattaneo, M. B.; Torrente, P.; Johnstone, A. D.
Italy, United Kingdom
Abstract
Bulk speed, density and temperature of the plasma are computed for protons and water-group ions in comet P/Halley using data from the two ion sensors of the JPA experiment flown on Giotto. Two water group ion populations, locally generated and implanted further upstream, evolve with different density and temperature during the fly-by. The centre of mass switches from the protons to the water group ions between 5.105 km and 1.5.105 km from closest approach and to the locally picked up ions further in. The data suggest that both the protons and the higher energy ions contribute to the charge exchange in the cometopause region.