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The standard model for the origin of galactic magnetic fields is through the amplification of seed fields via dynamo or turbulent processes to the level consistent with present observations (1-3). Although other mechanisms may also operate (4,5), currents from misaligned pressure and temperature gradients (the Biermann battery process) inevitably accompany the formation of galaxies in the absence of a primordial field. Driven by geometrical asymmetries in shocks (6) associated with the collapse of protogalactic structures, the Biermann battery is believed to generate tiny seed fields to a level of about [10.sup.-21] gauss (refs 7, 8). With the advent of high-power laser systems in the past two decades, a new area of research has opened in which, using simple scaling relations (9,10), astrophysical environments can effectively be reproduced in the laboratory (11,12). Here we report the results of an experiment that produced seed magnetic fields by the Biermann battery effect. We show that these results can be scaled to the intergalactic medium, where turbulence, acting on timescales of around 700 million years, can amplify the seed fields (13,14) sufficiently to affect galaxy evolution., We conducted these experiments at the Laboratoire pour l'Utilisation de Lasers Intenses (LULI 2000) laser facility. The intense laser was used to illuminate a small carbon rod inside a low-pressure [...]

The maximum energy for cosmic ray acceleration at supernova shock fronts is usually thought to be limited to around 10[sup 14]–10[sup 15] eV by the size of the shock and the time for which it propagates at high velocity. We show that the magnetic field can be amplified non-linearly by the cosmic rays to many times the pre-shock value, thus increasing the acceleration rate and facilitating acceleration to energies well above 10[sup 15] eV. A supernova remnant expanding into a uniform circumstellar medium may accelerate protons to 10[sup 17] eV and heavy ions, with charge Ze, to Z×10[sup 17] eV. Expansion into a pre-existing stellar wind may increase the maximum cosmic ray energy by a further factor of 10. [ABSTRACT FROM AUTHOR]

Studies the interaction of a picosecond laser pulse with a solid target. Maximum energy cutoff; Range of the hot electron temperatures; Observation of the collimation of the plasma flow.

Reports on the production of well-collimated jets by the pinch effect, by an azimuthal magnetic field in a series of three idealized magnetohydrodynamic (MHD) calculations in cylindrical geometry. Generation of magnetic field by crossed density and temperature gradients; Susceptibility of plasmas confined by magnetic pinching to MHD instability.

Discusses the use of a two-dimensional magnetohydrodynamic simulation incorporating cold start conditions to explain the early phase of carbon fiber Z-pinch experiments. Reproduction of the rapid development of large scale, nonlinear perturbations in the plasma corona; X-ray bright spot formation in the necks of the instability.