Universität zu Köln

Russell, C. T., Wei, H. Y., Cowee, M. M., Neubauer, F. M. and Dougherty, M. K. (2016). Ion cyclotron waves at Titan. J. Geophys. Res-Space Phys., 121 (3). S. 2095 - 2104. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9402

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Abstract

During the interaction of Titan's thick atmosphere with the ambient plasma, it was expected that ion cyclotron waves would be generated by the free energy of the highly anisotropic velocity distribution of the freshly ionized atmospheric particles created in the interaction. However, ion cyclotron waves are rarely observed near Titan, due to the long growth times of waves associated with the major ion species from Titan's ionosphere, such as CH4+ and N-2(+). In the over 100 Titan flybys obtained by Cassini to date, there are only two wave events, for just a few minutes during T63 flyby and for tens of minutes during T98 flyby. These waves occur near the gyrofrequencies of proton and singly ionized molecular hydrogen. They are left-handed, elliptically polarized, and propagate nearly parallel to the field lines. Hybrid simulations are performed to understand the wave growth under various conditions in the Titan environment. The simulations using the plasma and field conditions during T63 show that pickup protons with densities ranging from 0.01 cm(-3) to 0.02 cm(-3) and singly ionized molecular hydrogens with densities ranging from 0.015 cm(-3) to 0.25 cm(-3) can drive ion cyclotron waves with amplitudes of similar to 0.02nT and of similar to 0.04nT within appropriate growth times at Titan, respectively. Since the T98 waves were seen farther upstream than the T63 waves, it is possible that the instability was stronger and grew faster on T98 than T63.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Russell, C. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wei, H. Y. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cowee, M. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Neubauer, F. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dougherty, M. K. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-283807
DOI:	10.1002/2015JA022293
Journal or Publication Title:	J. Geophys. Res-Space Phys.
Volume:	121
Number:	3
Page Range:	S. 2095 - 2104
Date:	2016
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9402
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MAGNETOSPHERE Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28380