Formation of electron radiation belts at Saturn by Z-mode wave acceleration

Woodfield, EE ORCID: https://orcid.org/0000-0002-0531-8814; Horne, RB ORCID: https://orcid.org/0000-0002-0412-6407; Glauert, SA ORCID: https://orcid.org/0000-0003-0149-8608; Menietti, JD; Shprits, YY; Kurth, WS. 2018 Formation of electron radiation belts at Saturn by Z-mode wave acceleration. Nature Communications, 9, 5062. 10.1038/s41467-018-07549-4

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Abstract/Summary

At Saturn electrons are trapped in the planet’s magnetic field and accelerated to relativistic energies to form the radiation belts, but how this dramatic increase in electron energy occurs is still unknown. Until now the mechanism of radial diffusion has been assumed but we show here that in-situ acceleration through wave particle interactions, which initial studies dismissed as ineffectual at Saturn, is in fact a vital part of the energetic particle dynamics there. We present evidence from numerical simulations based on Cassini spacecraft data that a particular plasma wave, known as Z-mode, accelerates electrons to MeV energies inside 4 RS (1 RS = 60,330 km) through a Doppler shifted cyclotron resonant interaction. Our results show that the Z-mode waves observed are not oblique as previously assumed and are much better accelerators than O-mode waves, resulting in an lectron energy spectrum that closely approaches observed values without any transport effects included.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1038/s41467-018-07549-4
ISSN:	20411723
Date made live:	30 Nov 2018 14:29 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/517060

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1038/s41467-018-07549-4

ISSN:

20411723

Date made live:

30 Nov 2018 14:29 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/517060