Pitch angle distributions of energetic electrons at Saturn

Carbary, J. F.; Mitchell, D. G.; Paranicas, C.; Roelof, E. C.; Krimigis, S. M.; Krupp, N.; Khurana, K. K.; Dougherty, M. K.

doi:10.1029/2010ja015987

Cited by 26 publications

(46 citation statements)

References 36 publications

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“…At some distance near ∼10 R S , the injections become less frequent and energy loss processes (such as passing through the neutral torus) become significant. Also significant, the pitch angle distributions tend to be field aligned outside ∼10 R S and more isotropic or pancake inside, which has also been documented [ Schippers et al , 2008; Carbary et al , 2011]. The field‐aligned distributions were interpreted as consistent with a low‐altitude polar source for the energetic electrons [ Carbary et al , 2011].…”

Section: Binning In Radial Distancementioning

confidence: 63%

Energetic electron spectra in Saturn's plasma sheet

et al. 2011

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The differential spectra of energetic electrons (27–400 keV) in Saturn's plasma sheet can be characterized by power law or kappa distributions. Using all available fluxes from 2005 to 2010, fits to these distributions reveal a striking and consistent pattern of radial dependence in Saturn's plasma sheet (∣z∣ < 1 RS = 60,268 km). The electron spectral indices show harder spectra at large radial distances (20–30 RS), softer spectra at middle radial distances (10–20 RS), and very steep spectra inside the orbit of Rhea (∼8.5 RS). The dayside spectra are somewhat harder than the nightside spectra outside the orbit of Titan (∼20 RS), although there is no local time dependence inside ∼10 RS. This spectral behavior exhibited essentially no dependence on pitch angle and remained remarkably constant throughout the Cassini mission. Inward of about 10 RS, the presence of the electron radiation belts and losses of lower‐energy electrons to the gas and grain environment give rise to the very hard spectra in the inner magnetosphere, while the hard spectra in the outer magnetosphere may derive from auroral acceleration at high latitudes. The gradual softening of the spectra from 20 to 10 RS is explained by inward radial diffusion.

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Section: Binning In Radial Distancementioning

confidence: 63%

Energetic electron spectra in Saturn's plasma sheet

et al. 2011

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“…A variety of other processes, such as diffusion, convection or large scale injections may also transport particles from the outer magnetosphere to the ring current (Kollmann et al, 2011;Andriopoulou et al, 2014;Mitchell et al, 2015b). Similarities between the electron pitch angle distributions of the ring current Carbary et al (2011) and that of a QP60 (Fig. 14) are also not against of a transport between the two regions.…”

Section: Qp60 As a Magnetospheric Electron Sourcementioning

confidence: 93%

Quasi-periodic injections of relativistic electrons in Saturn’s outer magnetosphere

Roussos

Krupp

Mitchell

et al. 2016

Icarus

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“…We do not show this here, because the change in intensity with α 0 is smaller than the standard deviation. Pitch angle distributions taken within short time intervals during one orbit can be found for example by Carbary et al [2011] and Roussos et al [2011] and typically show changes less than an order of magnitude.…”

Section: Particle Profilesmentioning

confidence: 99%

Energetic particle phase space densities at Saturn: Cassini observations and interpretations

et al. 2011

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[1] Saturn's magnetosphere has been studied extensively by the Cassini spacecraft during the last 6 years. We present mission-averaged energetic proton and electron measurements obtained by the MIMI/LEMMS instrument onboard Cassini in an energy range from several 10 keV to several 10 MeV separated by equatorial pitch angle. We discuss the resulting radial profiles and energy spectra. The measured intensities are converted to phase space densities. The distribution of energetic particles is governed by a large variety of processes. For instance, moons absorb energetic particles, creating macrosignatures or microsignatures. We have found that the moon Rhea is partly responsible for a change in gradient of electron phase space densities. We show that, in contrast to larger distances, the particle distribution for L < 8 is not driven by radial diffusion alone. There, the particle profiles are significantly modified due to Saturn's Neutral Torus, plasma environment, E ring, injection events, and cosmic ray albedo neutron decay. Large parts of our analysis are focused near L = 7. There, protons are lost within the Neutral Torus and not the E ring. For electrons, we find that these two losses are of comparable rate but have discovered that neither process is the dominant driver of loss. We point out that intensity measured by a energy channel, such as in a particle instrument, can actually increase in the region of ring and torus instead of decrease. The importance of injection events is shown to be at least of similar importance as radial diffusion.

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Pitch angle distributions of energetic electrons at Saturn

Cited by 26 publications

References 36 publications

Energetic electron spectra in Saturn's plasma sheet

Energetic electron spectra in Saturn's plasma sheet

Quasi-periodic injections of relativistic electrons in Saturn’s outer magnetosphere

Energetic particle phase space densities at Saturn: Cassini observations and interpretations

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