Extending the radial diffusion model of Falthammar to non-dipole background field

doi:10.2172/1182627

GSTDTAP > 地球科学

DOI	10.2172/1182627
报告编号	LA-UR--15-23879
来源ID	OSTI ID: 1182627
	Extending the radial diffusion model of Falthammar to non-dipole background field
	Cunningham, Gregory Scott
	2015-05-26
出版年	2015
页数	30
语种	英语
国家	美国
领域	地球科学
英文摘要	A model for radial diffusion caused by electromagnetic disturbances was published by Falthammar (1965) using a two-parameter model of the disturbance perturbing a background dipole magnetic field. Schulz and Lanzerotti (1974) extended this model by recognizing the two parameter perturbation as the leading (non--dipole) terms of the Mead Williams magnetic field model. They emphasized that the magnetic perturbation in such a model induces an electric ield that can be calculated from the motion of field lines on which the particles are âfrozenâ. Roederer and Zhang (2014) describe how the field lines on which the particles are frozen can be calculated by tracing the unperturbed field lines from the minimum-B location to the ionospheric footpoint, and then tracing the perturbed field (which shares the same ionospheric footpoint due to the frozen -in condition) from the ionospheric footpoint back to a perturbed minimum B location. The instantaneous change n Roederer L, dL/dt, can then be computed as the product (dL/dphi)(dphi/dt). dL/Dphi is linearly dependent on the perturbation parameters (to first order) and is obtained by computing the drift across L-labeled perturbed field lines, while dphi/dt is related to the bounce-averaged gradient-curvature drift velocity. The advantage of assuming a dipole background magnetic field, as in these previous studies, is that the instantaneous dL/dt can be computed analytically (with some approximations), as can the DLL that results from integrating dL/dt over time and computing the expected value of (dL)^2. The approach can also be applied to complex background magnetic field models like T89 or TS04, on top of which the small perturbations are added, but an analytical solution is not possible and so a numerical solution must be implemented. In this talk, I discuss our progress in implementing a numerical solution to the calculation of DLL* using arbitrary background field models with simple electromagnetic perturbations.
英文关键词	Heliospheric and Magnetospheric Physics radiation belts, radial diffusion
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来源平台	US Department of Energy (DOE)
引用统计
文献类型	科技报告
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/6889
专题	地球科学
推荐引用方式 GB/T 7714	Cunningham, Gregory Scott. Extending the radial diffusion model of Falthammar to non-dipole background field,2015.