| Simple Approximations of Quasi-Linear Diffusion Coefficients |
01 DEC 2007 |
10 pages |
| Authors:
J. M. Albert; AIR FORCE RESEARCH LAB HANSCOM AFB MA
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 | Quasi-linear diffusion by cyclotron-resonant plasma waves is likely a key ingredient of the behavior of electrons in the Earth's radiation belts. Multidimensional dynamical simulations are under development, which require the diffusion coefficients to be evaluated quickly as well as accurately. The recently developed parallel propagation approximation replaces the integration over wavenormal distribution to a closed form expression, and can be quite accurate. However, it can also perform badly, especially for ... |
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| Refractive Index and Wavenumber Properties for Cyclotron Resonant Quasilinear Diffusion by Cold Plasma Waves |
05 JUL 2007 |
9 pages |
| Authors:
J. M. Albert; AIR FORCE RESEARCH LAB HANSCOM AFB MA
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| Wave-particle interactions have a large effect on magnetospheric particles, in the radiation belts and elsewhere. Bounce-averaged quasilinear diffusion coefficients have been calculated for whistler hiss and chorus and electromagnetic ion cyclotron waves (EMIC), which are all believed to play major roles. To perform these calculations efficiently, techniques have been developed that use properties of the refractive index of these modes to identify ranges of wave-normal angle that are compatible with ... |
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| Multidimensional Quasi-Linear Diffusion of Radiation Belt Electrons |
28 JUL 2005 |
5 pages |
| Authors:
J. M. Albert; S. L. Young; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE WEATHER CENTER OF EXCELLENCE
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| We consider diffusion of outer zone radiation belt electrons by chorus waves. Quasi-linear diffusion coefficients valid outside the plasmasphere have only been calculated recently, and indicate that the energy and cross diffusion rates can be comparable to that for pitch angle diffusion. Proper solution of the diffusion equation for phase space density must therefore be based on the full diffusion tensor, but this has been plagued by numerical problems associated ... |
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| Evaluation of Quasi-Linear Diffusion Coefficients for Whistler Mode Waves in a Plasma with Arbitrary Density Ratio |
22 MAR 2005 |
13 pages |
| Authors:
J. M. Albert; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE WEATHER CENTER OF EXCELLENCE
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| Techniques are presented for efficiently evaluating quasi-linear diffusion coefficients for whistler mode waves propagating according to the full cold plasma index of refraction. In particular, the density ratio omega (sub pe)/Omega(sub e) can be small, which favors energy diffusion. This generalizes an approach, previously used for high-density hiss and electromagnetic ion cyclotron waves, of identifying (and omitting) ranges of wavenormal angle Theta that are incompatible with cyclotron resonant frequencies omega ... |
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| Low-Altitude Distribution of Radiation Belt Electrons |
10 NOV 2004 |
12 pages |
| Authors:
R. S. Selesnick; M. D. Looper; J. M. Albert; AEROSPACE CORP LOS ANGELES CA
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| A numerical simulation of the low-altitude electron radiation belt is described. It includes dependences on the electron's bounce and drift phases, equatorial pitch angle, and kinetic energy in the range of 1 to several MeV at L = 3.5. Physical processes in addition to the adiabatic electron motion are pitch angle diffusion and backscattering from a realistic model atmosphere. Quasi-linear diffusion coefficients are calculated from a model of the whistler ... |
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