Asymmetric Boundary Conditions Research Articles

Persistent particle anisotropies and magnetospheric models

The influence of an interplanetary particle anisotropy on the asymmetry of solar particle entry into the magnetotail is analysed in the diffusion as well as in the reconnection model. By time dependent diffusion calculations with an asymmetric boundary condition in a cylindrical tail lobe it can be shown that a north-south interplanetary anisotropy leads in the open as well as in the closed magnetosphere to essentially the same polar cap structures when observed with a dawn-dusk polar orbiting satellite. However, depending on the satellite orbit, an east-west interplanetary anisotropy can serve to distinguish between rival magnetospheric models. Comparison of our diffusion calculations with polar cap measurements during an east-west interplanetary anisotropy, as presented in Morfill and Scholer (1972), show a large discrepancy, whereas an open tail model fits these observations best.

Theoretically predictable effects and new interpretations in spin wave resonance of thin films with asymmetric boundary conditions

AbstractThe eigenvalue problem of the finite linear chain with arbitrary asymmetric boundary conditions is solved strictly. The results are used in quantum theory of spin wave resonance (SWR) in thin asymmetric ferromagnetic films. A theory providing some new interpretations of experimentally known effects in SWR and predicting new as yet unobserved effects is proposed. The results are visualized in an especial surface pinning diagram which should prove highly useful for the comparison of experimental data with the theory.

Conduction-Electron Spin Resonance

We have calculated (using a simple theory) the paramagnetic-resonance absorption by conduction electrons in a thin metallic sample, thus extending the earlier work of Dyson. Our results are for a metal sample of arbitrary thickness, with a static magnetic field ${\mathcal{H}}_{0}$ at arbitrary angle with respect to the sample surface, and under either classical or anomalous skin-effect conditions. The electromagnetic field is assumed to be incident normally on both sides of the sample, but the relative phase and/or amplitude on the two sides can be arbitrary (asymmetric excitations). Under anomalous skin-effect conditions, as the field ${\mathcal{H}}_{0}$ is rotated from parallel to normal, the shape of the spin-resonance line is modified. For asymmetric boundary conditions on the electromagnetic field, the line decreases in intensity (to zero under certain conditions). For a symmetric excitation, or when the electromagnetic field is incident on one side only, the line shows a slight decrease in intensity and a slight narrowing as the field is rotated. Numerical results are presented.

ASYMMETRY OF THE CONCENTRATION FRONT DURING MISCIBLE DISPLACEMENT IN POROUS MEDIA

During many feasible experiments concerning miscible displacement in porous media, it has been noted that the concentration front is slightly asymmetric. It is possible that this is due to an asymmetry in the boundary conditions which is present in most practicable displacement experiments. The present paper endeavors to investigate the influence of asymmetric boundary conditions upon the shape of the concentration front: The diffusivity equation basic to the theory of miscible displacement has been solved for the case of injection of fluid of constant concentration at one end of a long, linear porous medium. The solution has been effected by an electrical analogue computer. Curves showing the asymmetry are given.