Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

We present results from three-dimensional numerical simulations investigating the magnetohydrodynamics of cloud-wind interactions. The initial cloud is spherical, while the magnetic field is uniform and transverse to the cloud motion. A simplified analytical model that describes the magnetic energy evolution in front of the cloud is developed and compared with simulation results. In addition, it is found that the interaction of the cloud with a magnetized interstellar medium results in the formation of a highly structured magnetotail. The magnetic flux in the wake of the cloud organizes into flux ropes, and a reconnection current sheet is developed as field lines of opposite polarity are brought close together near the symmetry axis. At the same time magnetic pressure is strongly enhanced at the leading edge of the cloud from the stretching of the field lines that occurs there. This has an important dynamical effect on the subsequent evolution of the cloud, since some unstable modes tend to be strongly enhanced.

Abstract:

The ultraintense laser plasma interaction experiments have produced observations of new phenomenon such as: the acceleration of electrons to high energies; production of intense proton beams; and the generation of magnetic fields. Observations of proton emission indicate significant structure in the energy spectrum and angular emission profile which varies with energy. The two different components of ion emission observed are a high energy component and a low energy component.