4 research outputs found
Multi-scale magnetic field structures in an expanding elongated plasma cloud with hot electrons subject to an external magnetic field
We carry out 3D and 2D PIC-simulations of the expansion of a magnetized
plasma that initially uniformly fills a half-space and contains a
semi-cylindrical region of heated electrons elongated along the surface of the
plasma boundary. This geometry is related, for instance, to the ablation of a
plane target by a femtosecond laser beam under quasi-cylindrical focusing. We
find that the decay of the inhomogeneous plasma--vacuum discontinuity is
strongly affected by an external magnetic field parallel to its boundary.
We observe various transient phenomena, including the anisotropic scattering
of electrons and the accompanying Weibel instability, and reveal various
spatial structures of the arising magnetic field and current, including
multiple flying apart filaments of a z-pinch type and slowly evolving current
sheets with different orientations. The magnitude of the self-generated
magnetic field can be of the order of or significantly exceed that of the
external one. Such phenomena are expected in the laser and cosmic plasmas,
including the explosive processes in the planetary magnetospheres and stellar
coronal arches.Comment: 13 pages, 6 figures, submitted to JP