A model of the secondary radiation belt

Selesnick, R. S.; Looper, M. D.; Mewaldt, R. A.

doi:10.1029/2008ja013593

Cited by 5 publications

(4 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The neutrons undergo β-decay, transferring most of their kinetic energy to the daughter protons (∼100 MeV) and lesser energy to the electrons (<1 MeV) (see [199]). A secondary source of the inner zone protons, particularly at the lower energy tail of the spectrum (<50 MeV), is solar energetic protons from production at solar flares and ICME shocks [200], [201], [202], [203]. These protons become trapped as they enter the inner zone and get scattered owing to their gyroradii being larger than the local magnetic gradient scale-lengths.…”

Section: Radiation Belts/energeticmentioning

confidence: 99%

Space Plasma Physics: A Review

Hajra

Zank

Sterken³

et al. 2023

IEEE Trans. Plasma Sci.

View full text Add to dashboard Cite

Section: Radiation Belts/energeticmentioning

confidence: 99%

Space Plasma Physics: A Review

Hajra

Zank

Sterken³

et al. 2023

IEEE Trans. Plasma Sci.

View full text Add to dashboard Cite

“…The proton model incorporates inelastic nuclear scattering from neutral atoms and ions as a part of the total lifetime 𝜏, but its contribution is generally small compared to dE∕dt (Selesnick et al, 2007). Elastic nuclear (Coulomb) scattering could be included as a mechanism of pitch-angle diffusion but is expected to produce only a small change in the quasi-steady proton distribution over long intervals (Selesnick et al, 2008). It is easy to confirm that its effect on proton decay rates at L = 1.5 is negligible.…”

Section: Elastic Nuclear Scatteringmentioning

confidence: 99%

Variability of the Proton Radiation Belt

Selesnick

Albert

2019

JGR Space Physics

Self Cite

View full text Add to dashboard Cite

Significant steady but slow variability of radiation belt proton intensity, in the energy range ∼19–200 MeV and for L<2.4, has been observed in an empirical model derived from data taken by Van Allen Probes during 2013–2019. It is compared to predictions of a theoretical model based on measured initial and boundary conditions. Two aspects of the variability are considered in detail and require adjustments to model parameters. Observed inward transport of proton intensity maxima near L=1.9 and associated increasing intensity are caused in the model by inward radial diffusion from an external source while conserving the first two adiabatic invariants. The diffusion coefficient is constrained by these observations and is required to have increased near the start of 2015 by a factor ∼2. Observed decay of proton intensity at L<1.6 can be caused only in part by energy loss to free and bound electrons in the local plasma and neutral atmosphere. Another, unknown loss mechanism is required to match observed proton decay rates as a function of energy. Accounting for the expected influence of slow radial diffusion at low L, the additional loss should have a mean lifetime near 22 years, independent of L and energy in the range ∼19–70 MeV. Several candidate loss mechanisms are considered—added plasma or neutral density, elastic Coulomb scattering, plasma wave scattering, field‐line curvature scattering, and collision with orbital debris—but none are found viable.

show abstract

“…A candidate for the additional loss process is elastic nuclear (Coulomb) scattering from the neutral atmosphere and ambient plasma. However, this was shown previously to have only a minor influence on trapped proton intensity [Selesnick et al, 2008]. In fact, the scattering lifetime at L = 1.5 is ∼10 5 years , much longer than the required value of ∼120 years.…”

Section: 1002/2015ja022154mentioning

confidence: 99%

Inward diffusion and loss of radiation belt protons

et al. 2016

Self Cite

View full text Add to dashboard Cite

Radiation belt protons in the kinetic energy range 24 to 76 MeV are being measured by the Relativistic Electron Proton Telescope on each of the two Van Allen Probes. Data have been processed for the purpose of studying variability in the trapped proton intensity during October 2013 to August 2015. For the lower energies (≲32 MeV), equatorial proton intensity near L = 2 showed a steady increase that is consistent with inward diffusion of trapped solar protons, as shown by positive radial gradients in phase space density at fixed values of the first two adiabatic invariants. It is postulated that these protons were trapped with enhanced efficiency during the 7 March 2012 solar proton event. A model that includes radial diffusion, along with known trapped proton source and loss processes, shows that the observed average rate of increase near L = 2 is predicted by the same model diffusion coefficient that is required to form the entire proton radiation belt, down to low L, over an extended (∼103 year) interval. A slower intensity decrease for lower energies near L = 1.5 may also be caused by inward diffusion, though it is faster than predicted by the model. Higher‐energy (≳40 MeV) protons near the L = 1.5 intensity maximum are from cosmic ray albedo neutron decay. Their observed intensity is lower than expected by a factor ∼2, but the discrepancy is resolved by adding an unspecified loss process to the model with a mean lifetime ∼120 years.

show abstract

A model of the secondary radiation belt

Cited by 5 publications

References 24 publications

Space Plasma Physics: A Review

Space Plasma Physics: A Review

Variability of the Proton Radiation Belt

Inward diffusion and loss of radiation belt protons

Contact Info

Product

Resources

About