Numerical analysis and theory of oblique alfvenic solitons observed in the interplanetary magnetic field.

摘要

Recently, there have been reports of small magnetic pulses or bumps in the interplanetary magnetic field observed by various spacecraft. Most of these reports claim that these localized pulses or bumps are solitons. Solitons are weakly nonlinear localized waves that tend to retain their form as they propagate and can be observed in various media which exhibit nonlinear steepening and dispersive eects. This thesis expands the claim that these pulses or bumps are nonlinear oblique Alfven waves with soliton components, through the application of analytical techniques used in the inverse scattering transform in a numerical context and numerical integration of nonlinear partial dierential equations. One event, which was observed by the Ulysses spacecraft on February 21st, 2001, is extensively scrutinized through comparison with soliton solutions that emerge from the Derivative Nonlinear Schrodinger (DNLS) equation. The direct scattering transform of a wave prole that has corresponding morphology to the selected magnetic bump leads to the implication of a soliton component. Numerical integration of the scaled prole matching the event in the context of the DNLS leads to generation of dispersive waves and a one parameter dark soliton.