It has recently been demonstrated experimentally that a turbulent plasma created by the collision of two inhomogeneous, asymmetric, weakly magnetized, laser-produced plasma jets can generate strong stochastic magnetic fields via the small-scale turbulent dynamo mechanism, provided the magnetic Reynolds number of the plasma is sufficiently large. In this paper, we compare such a plasma with one arising from two pre-magnetized plasma jets whose creation is identical save for the addition of a strong external magnetic field imposed by a pulsed magnetic field generator. We investigate the differences between the two turbulent systems using a Thomson-scattering diagnostic, x-ray self-emission imaging, and proton radiography. The Thomson-scattering spectra and x-ray images suggest that the external magnetic field has a limited effect on the plasma dynamics in the experiment. Although the external magnetic field induces collimation of the flows in the colliding plasma jets and although the initial strengths of the magnetic fields arising from the interaction between the colliding jets are significantly larger as a result of the external field, the energies and morphologies of the stochastic magnetic fields post-amplification are indistinguishable. We conclude that, for turbulent laser-plasmas with supercritical magnetic Reynolds numbers, the dynamo-amplified magnetic fields are determined by the turbulent dynamics rather than the seed fields or modest changes in the initial flow dynamics of the plasma, a finding consistent with theoretical expectations and simulations of turbulent dynamos.

Department of Physics,University of Oxford,Oxford,United Kingdom;Department of Astrophysical Sciences,University of Princeton,Princeton,New Jersey 08544,USA;Department of Physics and Astronomy,University of Rochester,Rochester,New York 14627,USA;Laboratory for Laser Energetics,University of Rochester,Rochester,New York 14623,USA;School of Mathematics and Physics,Queens University Belfast,Belfast,United Kingdom;Rutherford Appleton Laboratory,Chilton,Didcot,United Kingdom;Department of Physics,University of Strathclyde,Glasgow,United Kingdom;Massachusetts Institute of Technology,Cambridge,Massachusetts 02139,USA;Lawrence Livermore National Laboratory,Livermore,California 94550,USA;Max-Planck-Institut für Kernphysik,Heidelberg,Germany;Department of Physics,School of Natural Sciences,UNIST,Ulsan,South Korea;Department of Physics,University of Nevada,Reno,Nevada 89557,USA;Department of Astronomy and Astrophysics,University of Chicago,Chicago,Illinois 60637,USA

[1]A.F.A.Bott;L.Chen;P.Tzeferacos;C.A.J.Palmer;A.R.Bell;R.Bingham;A.Birkel;D.H.Froula;J.Katz;M.W.Kunz;C.-K.Li;H-.Park;R.Petrasso;J.S.Ross;B.Reville;D.Ryu;F.H.Séguin;T.G.White;A.A.Schekochihin;D.Q.Lamb;G.Gregori-.Insensitivity of a turbulent laser-plasma dynamo to initial conditions)[J].极端条件下的物质与辐射（英文）,2022(04):50-64

Insensitivity,collimation

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