Strong space plasma magnetic barriers and Alfvénic collapse.

High-magnitude magnetic barriers in space and solar plasma are proposed to be attributed to the pile up of magnetic field lines and their Alfvénic collapse for MHD flows. The analysis of experimental data from both the Interball and Cluster spacecrafts shows that high-magnitude magnetic structures found in the Earth magnetosheath and near the magnetopause are supported by a nearly thermal transverse plasma flow, with the minimum barrier width being on the order of the ion gyroradius. The collapse termination at such scales can be explained by the balance between the pile up of magnetic field lines and backward finite-gyroradius diffusion. Comparison between the theoretical, modeling, and experimental data shows that the Alfvénic collapse is, in general, a promising mechanism for magnetic field generation and plasma separation. [ABSTRACT FROM AUTHOR]