Bibliography

Large amplitude electric and magnetic field signatures in the inner magnetosphere during injection of 15 MeV electron drift echoes

Electric and magnetic fields were measured by the CRRES spacecraft at an L-value of 2.2 to 2.6 near 0300 magnetic local time during a strong storm sudden commencement (SSC) on March 24, 1991. The electric field signature at the spacecraft at the time of the SSC was characterized by a large amplitude oscillation (80 mV/m peak to peak) with a period corresponding to the 150 second drift echo period of the simultaneously observed 15 MeV electrons. Considerations of previous statistical studies of the magnitude of SSC electric and magnetic fields versus local time and analysis of the energization and cross-L transport of the particles imply the existence of 200 to 300 mV/m electric fields over much of the dayside magnetosphere. These observations also suggest that the 15 MeV drift echo electrons were selectively energized because their gradient drift velocity allowed them to reside in the region of strong electric fields for the duration of the accelerating phase of the electric field.

Wygant, J.; Mozer, F.; Temerin, M.; Blake, J.; Maynard, N.; Singer, H.; Smiddy, M.;

Published by: Geophysical Research Letters      Published on: 08/1994

YEAR: 1994     DOI: 10.1029/94GL00375

Shock-Induced Transport. Slot Refilling and Formation of New Belts.

Simulation of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC

We model the rapid (\~ 1 min) formation of a new electron radiation belt at L ≃ 2.5 that resulted from the Storm Sudden Commencement (SSC) of March 24, 1991 as observed by the CRRES satellite. Guided by the observed electric and magnetic fields, we represent the time-dependent magnetospheric electric field during the SSC by an asymmetric bipolar pulse that is associated with the compression and relaxation of the Earth\textquoterights magnetic field. We follow the electrons using a relativistic guiding center code. The test-particle simulations show that electrons with energies of a few MeV at L > 6 were energized up to 40 MeV and transported to L ≃ 2.5 during a fraction of their drift period. The energization process conserves the first adiabatic invariant and is enhanced due to resonance of the electron drift motion with the time-varying electric field. Our simulation results, with an initial W-8 energy flux spectra, reproduce the observed electron drift echoes and show that the interplanetary shock impacted the magnetosphere between 1500 and 1800 MLT.

Li, Xinlin; Roth, I.; Temerin, M.; Wygant, J.; Hudson, M.; Blake, J.;

Published by: Geophysical Research Letters      Published on: 11/1993

YEAR: 1993     DOI: 10.1029/93GL02701

Shock-Induced Transport. Slot Refilling and Formation of New Belts.

Velocity Space Diffusion from Weak Plasma Turbulence in a Magnetic Field

The quasi-linear velocity space diffusion is considered for waves of any oscillation branch propagating at an arbitrary angle to a uniform magnetic field in a spatially uniform plasma. The space-averaged distribution function is assumed to change slowly compared to a gyroperiod and characteristic times of the wave motion. Nonlinear mode coupling is neglected. An H-like theorem shows that both resonant and nonresonant quasi-linear diffusion force the particle distributions towards marginal stablity. Creation of the marginally stable state in the presence of a sufficiently broad wave spectrum in general involves diffusing particles to infinite energies, and so the marginally stable plateau is not accessible physically, except in special cases. Resonant particles with velocities much larger than typical phase velocities in the excited spectrum are scattered primarily in pitch angle about the magnetic field. Only particles with velocities the order of the wave phase velocities or less are scattered in energy at a rate comparable with their pitch angle scattering rate.

Kennel, C.;

Published by: Physics of Fluids      Published on: 12/1966

YEAR: 1966     DOI: 10.1063/1.1761629

Local Loss due to VLF/ELF/EMIC Waves

Limit on Stably Trapped Particle Fluxes

Whistler mode noise leads to electron pitch angle diffusion. Similarly, ion cyclotron noise couples to ions. This diffusion results in particle precipitation into the ionosphere and creates a pitch angle distributon of trapped particles that is unstable to further wave growth. Since excessive wave growth leads to rapid diffusion and particle loss, the requirement that the growth rate be limited to the rate at which wave energy is depleted by wave propagation permits an estimate of an upper limit to the trapped equatorial particle flux. Electron fluxes >40 kev and proton fluxes >120 kev observed on Explorers 14 and 12, respectively, obey this limit with occasional exceptions. Beyond L = 4, the fluxes are just below their limit, indicating that an unspecified acceleration source, sufficient to keep the trapped particles near their precipitation limit, exists. Limiting proton and electron fluxes are roughly equal, suggesting a partial explanation for the existence of larger densities of high-energy protons than of electrons. Observed electron pitch angle profiles correspond to a diffusion coefficient in agreement with observed lifetimes. The required equatorial whistler mode wide band noise intensity, 10-2γ, is not obviously inconsistent with observations and is consistent with the lifetime and with limiting trapped particle intensity.

Kennel, C.; Petschek, H.;

Published by: Journal Geophysical Research      Published on: 01/1966

YEAR: 1966     DOI: 10.1029/JZ071i001p00001

Local Loss due to VLF/ELF/EMIC Waves