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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. Although other mechanisms may also operate, 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 associated with the collapse of protogalactic structures, the Biermann battery is believed to generate tiny seed fields to a level of about 10?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, astrophysical environments can effectively be reproduced in the laboratory. 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 sufficiently to affect galaxy evolution. [ABSTRACT FROM AUTHOR]

A three-axis, 2.5 mm overall diameter differential magnetic probe (also known as B-dot probe) is discussed in detail from its design and construction to its calibration and use as diagnostic of fast transient effects in exploding plasmas. A design and construction method is presented as a means to reduce stray pickup, eliminate electrostatic pickup, reduce physical size, and increase magnetic signals while maintaining a high bandwidth. The probe’s frequency response is measured in detail from 10 kHz to 50 MHz using the presented calibration method and compared to theory. The effect of the probe’s self-induction as a first order correction in frequency, O(ω), on experimental signals and magnetic field calculations is discussed. The probe’s viability as a diagnostic is demonstrated by measuring the magnetic field compression and diamagnetism of a sub-Alfvénic (∼500 km/s,MA∼0.36) flow created from the explosion of a high-density energetic laser plasma through a cooler, low-density, magnetized ambient plasma. [ABSTRACT FROM AUTHOR]

Paramagnetic Faraday rotator glass (rare-earth doped borosilicate) with a high Verdet constant will be used to measure the magnetic field inside of low density Helium plasmas (Te ∼ 5 eV, Ti ∼ 1 eV) with a density of n ∼ 1012 cm-3. Linearly polarized light is sent through the glass such that the plane of polarization is rotated by an angle that depends on the strength of the magnetic field in the direction of propagation and the length of the crystal (6 mm). The light is then passed into an analyzer and photo-detector setup to determine the change in polarization angle. This setup can detect magnetic fields up to 5 kG with a resolution of <5 G and a temporal resolution on the order of a nanosecond. The diagnostic will be used to characterize the structure and evolution of laser-driven collisionless shocks in large magnetized plasmas. [ABSTRACT FROM AUTHOR]