scholarly journals Deriving electromagnetic radial diffusion coefficients of radiation belt equatorial particles for different levels of magnetic activity based on magnetic field measurements at geostationary orbit

2013 ◽  
Vol 118 (6) ◽  
pp. 3147-3156 ◽  
Author(s):  
Solène Lejosne ◽  
Daniel Boscher ◽  
Vincent Maget ◽  
Guy Rolland
Keyword(s):  
Magnetic Field ◽  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Field Measurements ◽  
Magnetic Activity ◽  
Radial Diffusion ◽  
Geostationary Orbit ◽  
Magnetic Field Measurements ◽  
Different Levels

Radial diffusion coefficients database in the frame of SafeSpace project

2021 ◽  
Author(s):  
Christos Katsavrias ◽  
Ioannis A. Daglis ◽  
Afroditi Nasi ◽  
Constantinos Papadimitriou ◽  
Marina Georgiou
Keyword(s):  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Field Measurements ◽  
Radial Diffusion ◽  
Relativistic Electrons ◽  
Outer Radiation Belt ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
The Difference ◽  
Cycle 24

<p>Radial diffusion has been established as one of the most important mechanisms contributing the acceleration and loss of relativistic electrons in the outer radiation belt. Over the past few years efforts have been devoted to provide empirical relationships of radial diffusion coefficients (D<sub>LL</sub>) for radiation belt simulations yet several studies have suggested that the difference between the various models can be orders of magnitude different at high levels of geomagnetic activity as the observed D<sub>LL</sub> have been shown to be highly event-specific. In the frame of SafeSpace project we have used 12 years (2009 – 2020) of multi-point magnetic and electric field measurements from THEMIS A, D and E satellites to create a database of calculated D<sub>LL</sub>. In this work we present the first statistics on the evolution of D<sub>LL </sub>during the various phases of Solar cycle 24 with respect to the various solar wind parameters and geomagnetic indices.</p><p>This work has received funding from the European Union's Horizon 2020 research and innovation programme “SafeSpace” under grant agreement No 870437.</p>

Methodology for calculation of radial diffusion coefficients for a relativistic electron population from hybrid-Vlasov simulation

2021 ◽  
Author(s):  
Harriet George ◽  
Emilia Kilpua ◽  
Adnane Osmane ◽  
Urs Ganse ◽  
Solene Lejosne ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Time Derivative ◽  
Distribution Functions ◽  
Radial Diffusion ◽  
Outer Radiation Belt ◽  
Electron Population ◽  
Radial Diffusion Coefficient

<p>The relative importance of radial diffusion and local acceleration to the dynamics of outer radiation belt electron populations is an open question in radiation belt physics. A key component of this discussion is the calculation of the radial diffusion coefficients, which quantify the effect of radial diffusion on an electron population. However, there is currently a broad range of radial diffusion coefficient values in the literature, which presents difficulties when determining the dominant process governing radiation belt energisation. Here we develop a methodology for the calculation of radial diffusion coefficients using Vlasiator, a 5D hybrid-Vlasov simulation of near-Earth space, and calculate the radial diffusion coefficients for a 10 MeV electron population at multiple locations within the outer radiation belt.</p><p> </p><p>Vlasiator currently models ions as velocity distribution functions and electrons as a magnetohydrodynamic fluid, so the drift motion of the electron population can not be directly studied. However, the ion dynamics accurately determine the magnetic field in the inner magnetosphere, and the spatial and temporal magnetic field variations can be used to calculate the radial diffusion coefficient of a population according to principles outlined in Lejosne et. al. 2020.<span>  </span>Four magnetic field isocontours in the outer radiation belt are used to model the guiding centre drift contours of an electron population, and the corresponding Roederer L-star coordinates are calculated from the magnetic flux through each of these drift contours. The variation of the L-stars over time are calculated from population-specific variables and the Lagrangian magnetic field time derivative along the magnetic isocontours. The radial diffusion coefficients for the 10 MeV electron population are then calculated at each of these L-stars and compared to the literature. This methodology produces radial diffusion coefficients from Vlasiator that have the expected L-shell dependence and are consistent with the literature, including studies based on satellite measurements of radiation belt electrons. These results indicate that this is a valid methodology for the calculation of radial diffusion coefficients, and can therefore be extended to evaluate the radial diffusion coefficients in different solar wind conditions and at more L-stars.</p>

Magnetic field measurements in space

1963 ◽  
Vol 1 (3) ◽  
pp. 399-414 ◽  
Author(s):  
Laurence J. Cahill
Keyword(s):  
Magnetic Field ◽  
Field Measurements ◽  
Magnetic Field Measurements

High magnetic field measurements in high structural quality AlCuFe quasicrystals

1992 ◽  
Vol 177 (1-4) ◽  
pp. 516-518 ◽  
Author(s):  
H. Rakoto ◽  
T. Klein ◽  
C. Berger ◽  
G. Fourcaudot ◽  
J.C. Grieco ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Field Measurements ◽  
Structural Quality ◽  
Magnetic Field Measurements
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