Grid-induced turbulence in laser driven shock wave experiments and magnetic field generation

Although magnetic fields exist throughout the Universe, their origin is still uncertain. They are seen in galaxy clusters, filaments and voids, with intensities ranging from a few $\mu$G to a fraction of a fG. Thanks to the development of high power laser facilities it is now possible to study such astrophysical systems in the laboratory using simple scaling laws. We have developed a new experimental platform where we investigate the generation and amplification of tiny seed magnetic fields through induced turbulence. This was achieved by focusing the Vulcan laser ($\sim$300 J, 527 nm, 1 ns) onto a graphite rod, with the resultant blast wave propagating through ambient argon gas at 1 mbar pressure. A broad range of diagnostics including interferometric, schlieren and spectroscopic self-emission imaging along with temporally resolved induction coils were used to characterise the magnetic field and shock evolution. Homogeneous turbulence was generated by placing a wire mesh array in the path of the shock. Comparison with current models of turbulent amplification of magnetic fields are discussed.