Modeling of low-altitude quasi-trapped proton fluxes at the equatorial inner magnetosphere

Gusev, A. A.; Pugacheva, G. I.; Jayanthi, U. B.; Schuch, Nelson Jorge

doi:10.1590/s0103-97332003000400029

Cited by 13 publications

(10 citation statements)

References 17 publications

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“…Multiple charge exchange, as proposed by Gusev et al [2003], may also help explain the observations. Differential ion fluxes of the high‐energy energy component peak at equatorial pitch angles of 90°.…”

Section: Discussionmentioning

confidence: 66%

Long- and short-term variability of Saturn's ionic radiation belts

et al. 2011

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Earlier studies of Saturn's inner ionic radiation belts revealed that their content was surprisingly constant while their evolution appeared decoupled from dynamics of the Saturnian magnetosphere. Saturn's icy moons in combination with the neutral gas and dust that surround the planet seem to effectively restrict radial transport of energetic ions and are responsible for all these unusual characteristics. A possible process through which MeV ions may be populating the regions between the icy moons is cosmic ray albedo neutron decay (CRAND). While some circumstantial evidence suggests that this process actually occurs, the concept of CRAND has only been applied to the proton energy spectrum above ∼10 MeV; the source of ions below 10 MeV is not yet obvious. Additional hints about the nature of this source are now becoming evident by monitoring Saturn's radiation belts about half a solar cycle (from the declining phase of the solar maximum to solar minimum). Using Cassini's magnetosphere imaging instrument and low‐energy magnetospheric measurement system (MIMI/LEMMS) data from June 2004 to June 2010, we detect a weak intensification of the trapped proton component that probably originates from CRAND (>10 MeV). This anticipated enhancement, due to the solar cycle modulation of the galactic cosmic ray influx at Saturn, is closely followed by ions in the 1–10 MeV range. This observation sets constraints on the nature of those ions' source: this source should be connected (directly or indirectly) to the access of galactic cosmic rays in the Saturnian system. We also find evidence indicating that the ionic belts experience short‐term variability following the occurrence of solar energetic particle events at Saturn's distance, probably associated with coronal mass ejections that propagate in the heliosphere. LEMMS data contain clear evidence of Earth‐like Forbush decreases following such events. These decreases may explain the lack of an (expected) ionic belt intensification between 2004 and 2006.

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Section: Discussionmentioning

confidence: 66%

Long- and short-term variability of Saturn's ionic radiation belts

et al. 2011

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“…The surviving ions form the innermost ion belt, where the balance of stripping source and charge exchange loss determines its steady state intensity. Similar processes occur at Earth [ Moritz , ; Gusev et al , ], Mars [ Halekas et al , ], and possibly Saturn [ Krimigis et al , ]. A cartoon of the described series of charge exchange and stripping is shown in Figure a.…”

Section: Origin Of the Innermost Beltmentioning

confidence: 79%

A heavy ion and proton radiation belt inside of Jupiter's rings

Kollmann

Paranicas

Clark

et al. 2017

Geophysical Research Letters

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Energetic charged particle measurements by the Jupiter Energetic Particle Detector Instrument (JEDI) on board Juno have revealed a radiation belt of hundreds of keV ions up to the atomic mass of sulfur, located between Jupiter's rings and atmosphere. Proton energy spectra display an unusual intensity increase above 300 keV. We suggest that this is because charge exchange in Jupiter's neutral environment does not efficiently remove ions at such high energies. Since this innermost belt includes heavy ions, it cannot be exclusively supplied by cosmic ray albedo neutron decay, which is an important source at Earth and Saturn but only supplies protons and electrons. We find indications that the stripping of energetic neutral atoms in Jupiter's high atmosphere might be the ion source. Since the stripped off electrons are of low energy, this hypothesis is consistent with observations of the ratio of energetic electrons to ions being much less than 1.

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“…The altitudinal dependence in the bottom part of the IRB was investigated by the R3DR data (Dachev, Semkova et al, 2015). This is a well-known phenomenon that has been competently described elsewhere (Filz & Holeman, 1965;Gusev et al, 2003). Therefore, it will not be discussed further here.…”

Section: Irb Radiation Sourcementioning

confidence: 99%

Overview of the ISS Radiation Environment Observed during the ESA EXPOSE‐R2 Mission in 2014–2016

et al. 2017

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The radiation risk radiometer‐dosimeter (R3D)‐R2 solid‐state detector performed radiation measurements at the European Space Agency EXPOSE‐R2 platform outside of the Russian “Zvezda” module at the International Space Station (ISS) from 24 October 2014 to 11 January 2016. The ISS orbital parameters were average altitude of 415 km and 51.6° inclination. We developed special software and used experimentally obtained formulas to determine the radiation flux‐to‐dose ratio from the R3DR2 Liulin‐type deposited‐energy spectrometer. We provide for the first time simultaneous, long‐term estimates of radiation dose external to the ISS for four source categories: (i) galactic cosmic ray particles and their secondary products; (ii) protons in the South Atlantic Anomaly region of the inner radiation belt (IRB); (iii) relativistic electrons and/or bremsstrahlung in the outer radiation belt (ORB); and (iv) solar energetic particle (SEP) events. The latter category is new in this study. Additionally, in this study, secondary particles (SP) resulting from energetic particle interaction with the detector and nearby materials are identified. These are observed continuously at high latitudes. The detected SPs are identified using the same sorting requirements as SEP protons. The IRB protons provide the highest consistent hourly dose, while the ORB electrons and SEPs provide the most extreme hourly doses. SEPs were observed 11 times during the study interval. The R3DR2 data support calculation of average equivalent doses. The 30 day and 1 year average equivalent doses are much smaller than the skin and eyes doses recommendations by the National Council on Radiation Protection (Report 132), which provides radiation protection guidance for Low Earth Orbit.

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Modeling of low-altitude quasi-trapped proton fluxes at the equatorial inner magnetosphere

Cited by 13 publications

References 17 publications

Long- and short-term variability of Saturn's ionic radiation belts

Long- and short-term variability of Saturn's ionic radiation belts

A heavy ion and proton radiation belt inside of Jupiter's rings

Overview of the ISS Radiation Environment Observed during the ESA EXPOSE‐R2 Mission in 2014–2016

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