scholarly journals On the storm-time evolution of relativistic electron phase space density in Earth's outer radiation belt

2013 ◽  
Vol 118 (5) ◽  
pp. 2196-2212 ◽  
Author(s):  
D. L. Turner ◽  
V. Angelopoulos ◽  
W. Li ◽  
M. D. Hartinger ◽  
M. Usanova ◽  
...  
Keyword(s):  
Phase Space ◽  
Relativistic Electron ◽  
Time Evolution ◽  
Radiation Belt ◽  
Phase Space Density ◽  
Outer Radiation Belt ◽  
Space Density

Substorm Injections as a Source of Relativistic Electrons in Earth’s Outer Radiation Belt

2020 ◽  
Author(s):  
Drew Turner ◽  
Ian Cohen ◽  
Kareem Sorathia ◽  
Sasha Ukhorskiy ◽  
Geoff Reeves ◽  
...  
Keyword(s):  
Phase Space ◽  
Plasma Sheet ◽  
Radiation Belt ◽  
Energetic Electron ◽  
Local Source ◽  
Relativistic Electrons ◽  
Phase Space Density ◽  
Outer Radiation Belt ◽  
Space Density ◽  
Van Allen Probes

<p>Earth’s magnetotail plasma sheet plays a crucial role in the variability of Earth’s outer electron radiation belt. Typically, injections of energetic electrons from Earth’s magnetotail into the outer radiation belt and inner magnetosphere during periods of substorm activity are not observed exceeding ~300 keV.  Consistent with that, phase space density radial distributions of electrons typically indicate that for electrons below ~300 keV, there is a source of electrons in the plasma sheet while for electrons with energies above that, there is a local source within the outer radiation belt itself.  However, here we ask the question: is this always the case or can the plasma sheet provide a direct source of relativistic (> ~500 keV) electrons into Earth’s outer radiation belt via substorm injection? Using phase space density analysis for fixed values of electron first and second adiabatic invariants, we use energetic electron data from NASA’s Van Allen Probes and Magnetospheric Multiscale (MMS) missions during periods in which MMS observed energetic electron injections in the plasma sheet while Van Allen Probes concurrently observed injections into the outer radiation belt. We report on cases that indicate there was a sufficient source of up to >1 MeV electrons in the electron injections in the plasma sheet as observed by MMS, yet Van Allen Probes did not see those energies injected inside of geosynchronous orbit.  From global insight with recent test-particle simulations in global, dynamic magnetospheric fields, we offer an explanation for why the highest-energy electrons might not be able to inject into the outer belt even while the lower energy (< ~300 keV) electrons do. Two other intriguing points that we will discuss concerning these results are: i) what acceleration mechanism is capable of producing such abundance of relativistic electrons at such large radial distances (X-GSE < -10 RE) in Earth’s magnetotail? and ii) during what conditions (if any) might injections of relativistic electrons be able to penetrate into the outer belt?</p>

Phase Space Density Analysis of Outer Radiation Belt Electron Energization and Loss during Geoeffective and Nongeoeffective Sheath Regions

2021 ◽  
Author(s):  
Milla M. H. Kalliokoski ◽  
Emilia Kilpua ◽  
Adnane Osmane ◽  
Allison N Jaynes ◽  
Drew L. Turner ◽  
...  
Keyword(s):  
Phase Space ◽  
Radiation Belt ◽  
Phase Space Density ◽  
Outer Radiation Belt ◽  
Space Density ◽  
Density Analysis

Radial distributions of equatorial phase space density for outer radiation belt electrons

2012 ◽  
Vol 39 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
D. L. Turner ◽  
V. Angelopoulos ◽  
Y. Shprits ◽  
A. Kellerman ◽  
P. Cruce ◽  
...  
Keyword(s):  
Phase Space ◽  
Radiation Belt ◽  
Phase Space Density ◽  
Outer Radiation Belt ◽  
Space Density ◽  
Radiation Belt Electrons

Phase space density analysis of outer radiation belt electron energization and loss during geoeffective and non-geoeffective sheath regions

2021 ◽  
Author(s):  
Milla Kalliokoski ◽  
Emilia Kilpua ◽  
Adnane Osmane ◽  
Allison Jaynes ◽  
Drew Turner ◽  
...  
Keyword(s):  
Phase Space ◽  
Energetic Electron ◽  
Electron Content ◽  
Phase Space Density ◽  
Geomagnetic Disturbances ◽  
Interplanetary Coronal Mass Ejections ◽  
Outer Radiation Belt ◽  
Space Density ◽  
Sheath Region ◽  
Chorus Waves

<p>The energetic electron content in the Van Allen radiation belts surrounding the Earth can vary dramatically on timescales from minutes to days, and these electrons present a hazard for spacecraft traversing the belts. The outer belt response to solar wind driving is however yet largely unpredictable. Here we investigate the driving of the belts by sheath regions preceding interplanetary coronal mass ejections. Electron dynamics in the belts is governed by various competing acceleration, transport and loss processes. We analyzed electron phase space density to compare the energization and loss mechanisms during a geoeffective and a non-geoeffective sheath region. These two case studies indicate that ULF-driven inward and outward radial transport, together with the incursions of the magnetopause, play a key role in causing the outer belt electron flux variations. Chorus waves also likely contribute to energization during the geoeffective event. A global picture of the wave activity is achieved through a chorus proxy utilizing POES measurements. We highlight that also the non-geoeffective sheath presented distinct changes in outer belt electron fluxes, which is also evidenced by our statistical study of outer belt electron fluxes during sheath events. While not as intense as during geoeffective sheaths, significant changes in outer belt electron fluxes occur also during sheaths that do not cause major geomagnetic disturbances.</p>

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