Radiation Belt Processes in a Declining Solar Cycle

Abstract. New observations of energetic helium ion fluxes in the Earth's radiation belts have been obtained with the CAMMICE/HIT instrument on the ISTP/GGS POLAR spacecraft during the extended geomagnetically low activity period April through October 1996. POLAR executes a high inclination trajectory that crosses over both polar cap regions and passes over the geomagnetic equator in the heart of the radiation belts. The latter attribute makes possible direct observations of nearly the full equatorial helium ion pitch angle distributions in the heart of the Earth's radiation belt region. Additionally, the spacecraft often re-encounters the same geomagnetic flux tube at a substantially off-equatorial location within a few tens of minutes prior to or after the equatorial crossing. This makes both the equatorial pitch angle distribution and an expanded view of the local off-equatorial pitch angle distribution observable. The orbit of POLAR also permitted observations to be made in conjugate magnetic local time sectors over the course of the same day, and this afforded direct comparison of observations on diametrically opposite locations in the Earth's radiation belt region at closely spaced times. Results from four helium ion data channels covering ion kinetic energies from 520 to 8200 KeV show that the distributions display trapped particle characteristics with angular flux peaks for equatorially mirroring particles as one might reasonably expect. However, the helium ion pitch angle distributions generally flattened out for equatorial pitch angles below about 45°. Significant and systematic helium ion anisotropy difference at conjugate magnetic local time were also observed, and we report quiet time azimuthal variations of the anisotropy index.Key words. Magnetospheric physics (energetic particles · trapped; magnetospheric configuration and dynamics; plasmasphere)

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Van Allen Probes: Successful launch campaign and early operations exploring Earth's radiation belts

2013 IEEE Aerospace Conference ◽

10.1109/aero.2013.6496838 ◽

2013 ◽

Cited By ~ 2

Author(s):

K. Kirby ◽

J. Stratton

Keyword(s):

Radiation Belts ◽

Van Allen Probes ◽

Successful Launch ◽

Early Operations ◽

Earth's Radiation Belts

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OMEP-EOR: A MeV proton flux specification model for Electric Orbit Raising missions

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2021038 ◽

2021 ◽

Author(s):

Antoine Brunet ◽

Angélica Sicard ◽

Constantinos Papadimitriou ◽

Didier Lazaro ◽

Pablo Caron

Keyword(s):

Radiation Belt ◽

Temporal Dynamics ◽

Radiation Belts ◽

Proton Flux ◽

Radiation Environment ◽

Solar Arrays ◽

Proton Fluxes ◽

Van Allen Probes ◽

Spectrum Distribution ◽

Gp Model

Electric Orbit Raising (EOR) for telecommunication satellites has allowed significant reduction in on-board fuel mass, at the price of extended transfer durations. These relatively long transfers, which usually span a few months, cross large spans of the radiation belts, resulting in significant exposure of the spacecraft to space radiations. Since they are not very populated, the radiation environment of intermediate regions of the radiation belts is less constrained than on popular orbits such as LEO or GEO on standard environment models. In particular, there is a need for more specific models for the MeV energy range proton fluxes, responsible for solar arrays degradations, and hence critical for EOR missions. As part of the ESA ARTES program, ONERA has developed a specification model of proton fluxes dedicated for EOR missions. This model is able to estimate the average proton fluxes between 60 keV and 20MeV on arbitrary trajectories on the typical durations of EOR transfers. A global statistical model of the radiation belts was extracted from the Van Allen Probes (RBSP) RBSPICE data. For regions with no or low sampling, simulation results from the Salammbô radiation belt model were used. A special care was taken to model the temporal dynamics of the belts on the considered mission durations. A Gaussian Process (GP) model was developed, allowing to compute analytically the distribution of the average fluxes on arbitrary mission durations. Satellites trajectories can be flown in the resulting global distribution, yielding the proton flux spectrum distribution as seen by the spacecraft. We show results of the model on a typical EOR trajectory. The obtained fluxes are compared to the standard AP8 model, the AP9 model, and validated using the THEMIS satellites data.We illustrate the expected e ect on solar cell degradation, where our model is showing an increase of up to 20% degradation prediction compared to AP8.

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Increase in seismic activity near the footprints of new radiation belts forming after geomagnetic storms

10.5194/egusphere-egu21-2149 ◽

2021 ◽

Author(s):

Nursultan Toyshiev ◽

Galina Khachikyan ◽

Beibit Zhumabayev

Keyword(s):

Geomagnetic Storm ◽

Seismic Activity ◽

Radiation Belt ◽

Geomagnetic Storms ◽

Radiation Belts ◽

Tien Shan ◽

Relativistic Electrons ◽

Inner Magnetosphere ◽

Van Allen Probes ◽

Northern Tien Shan

Recently, attention was drawn [1] that after geomagnetic storms that cause formation of new radiation belts in slot region or in the inner magnetosphere, after about 2 months, there is an increase in seismic activity near the footprints of geomagnetic lines of new radiation belts. More detailed studies showed [2] that on May 30, 1991, an earthquake M=7.0 occurred in Alaska with (54.57N, 161.61E) near the footprint of geomagnetic line L = 2.69 belonging to new radiation belt, which was observed by the CRRES satellite [3] around geomagnetic lines 2<L<3 after geomagnetic storm on March 24, 1991. After geomagnetic storm on September 3, 2012, the Van Allen Probes satellites observed new radiation belt around 3.0&#8804;L&#8804;3.5 [4], and about 2 months later, on October 28, 2012, earthquake M=7.8 occurred off the coast of Canada (52.79N, 132.1W) near the footprint of geomagnetic line L=3.32 belonging to the new radiation belt. Also, Van Allen Probes observed new radiation belt around L=1.5-1.8 after geomagnetic storm on June 23, 2015 [5], and ~2 months later, in September 2015, seismic activity noticeably increased near the footprint of these geomagnetic lines. We consider variations in seismic activity in connection with the strongest geomagnetic storms in 2003 with Dst~- 400 nT (Halloween Storm) and the formation of a belt of relativistic electrons in the inner magnetosphere around L~1.5 existed until the end of 2005 as observed SAMPEX [6]. Analysis of data from the USGS global seismological catalog showed that near the footprint of geomagnetic lines L=1.4-1.6 the number of earthquakes with M&#8805;4.5 increased in 2003-2004 by ~70% compared with their number in two previous years. On the Northern Tien Shan, on December 1, 2003 a strong for the region earthquake M=6.0 occurred on the border of Kazakhstan and China (42.9N, 80.5E) near the footprint of L = 1.63, adjacent to the new radiation belt.

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Electron filling and proton loss in radiation belts and SAA during 2018 storm based on ZH-1 satellite observations

10.5194/egusphere-egu21-1529 ◽

2021 ◽

Author(s):

Zhenxia Zhang

Keyword(s):

Geomagnetic Storm ◽

Radiation Belt ◽

Electron Flux ◽

Outer Boundary ◽

Energetic Electron ◽

High Energy ◽

Radiation Belts ◽

High Energy Particle ◽

Van Allen Probes ◽

Proton Loss

Based on data from the ZH-1 satellites, companied with Van Allen Probes and NOAA observations, we analyze the high energy particle evolutions in radiation belts, slot region and SAA during August 2018 major geomagnetic storm (minimum Dst &#8776; &#8722;190 nT).&#160;&#160;&#160;1) Relativistic electron enhancements in extremely low L-shell regions (reaching L &#8764; 3) were observed during storm. Contrary to what occurs in the outer belt, such an intense and deep electron penetration event is rare and more interesting. Strong whistler-mode (chorus and hiss) waves, with amplitudes 81&#8211;126 pT, were also observed in the extremely low L-shell simultaneously (reaching L &#8764; 2.5) where the plasmapause was suppressed. The bounce-averaged diffusion coefficient calculations support that the chorus waves can play a significantly important role in diffusing and accelerating the 1&#8211;3 MeV electrons even in such low L-shells during storms.2) A robust evidence is clearly demonstrated that the energetic electron flux with energy 30&#8764;600 keV are increased by 2&#8764;3 times in the inner radiation belt near equator and SAA region on dayside during the major geomagnetic storm. This is the first time that the 100s keV electron flux enhancement is reported to be potentially induced by the interaction with magnetosonic waves in extremely low L-shells (L<2) observed by Van Allen Probes. Proton loss in outer boundary of inner radiation belt takes place in energy of 2~220 MeV extensively during the occurrence of this storm but the loss mechanism is energy dependence which is consistent with some previous studies. It is confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon in energy 30-100 MeV during this storm. This work provides a beneficial help to comprehensively understand the charged particles trapping and loss in SAA region and inner radiation belt dynamic physics.

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A Proton Flux Model Dedicated to Solar Arrays Degradations on Electric Orbit Raising Missions

10.5194/egusphere-egu21-7342 ◽

2021 ◽

Author(s):

Antoine Brunet ◽

Angélica Sicard ◽

Constantinos Papadimitriou ◽

Didier Lazaro

Keyword(s):

Radiation Belt ◽

Temporal Dynamics ◽

Radiation Belts ◽

Radiation Environment ◽

Solar Arrays ◽

Proton Fluxes ◽

Van Allen Probes ◽

Orbital Transfers ◽

Flux Model ◽

Simulation Results

Electric Orbit Raising (EOR) for telecommunication satellites has allowed significant reduction in onboard fuel mass, at the price of extended transfer durations. These relatively long orbital transfers, which can take up to a few months, equatorially cross most of the radiation belts, resulting in significant exposure of the spacecraft to space radiations. Since there are not covered by many spacecrafts, the radiation environment of intermediate regions of the radiation belts is less known than on popular orbits such as LEO or GEO. In particular, there is a need for more specific models for the MeV energy range proton fluxes, responsible for solar arrays degradations. We present a model of proton fluxes dedicated for EOR missions that was developped as part of the ESA ARTES program. This model is able to estimate the average proton fluxes between 60 keV and 10MeV on arbitrary trajectories on the typical durations of EOR transfers. A global statistical model of the radiation belts was extracted from the Van Allen Probes (RBSP) RBSPICE data and enriched by simulation results from the Salammb&#244; radiation belt model were used. A special care was taken to model the temporal dynamics of the proton belt, allowing to compute analytically the distribution of the average fluxes on arbitrary EOR missions.

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