Supersonic Turbulent Dynamo in Laser-driven Plasma

Magnetic fields are believed to play a significant role in the dynamics of the interstellar medium (ISM) [1]. Previous experiments conducted at the OMEGA-60 laser facility have demonstrated magnetic field amplification via turbulent dynamo action in subsonic plasmas [2]. However, radiative supersonic turbulence – which is crucial in star formation processes [3], and the stellar mass distribution [4] – is predicted to be less efficient at amplifying magnetic fields [5]. To investigate the properties of supersonic turbulent dynamo, including its dependence on the turbulent Mach number and magnetic Reynolds number, we conducted a laser-plasma experiment on the OMEGA-60 facility. In this experiment, CH foils doped with 6% chlorine were illuminated by ten 500-J, 1-ns laser beams. The plasma expansion was perturbed by grids, introducing asymmetry between counter-propagating jets and generating significant stochasticity in the resulting interaction region. The evolution of this turbulent plasma was diagnosed using temporally resolved, frequency-doubled optical Thomson scattering, x-ray emission imaging, and proton radiography. This experiment demonstrates, for the first time, the realization of supersonic turbulent dynamo in a laboratory environment.

References

[1] Zweibel et al., Nature 385, 131 (1997)

[2] Tzeferacos et al., Nat. Commun. 9, 591 (2018)

[3] Krumholz et al., Front. Astron. Space Sci. 6, 7 (2019)

[4] Padoan et al., Astrophys. J. 576, 870 (2002)

[5] Bott et al., Phys. Rev. Lett. 127, 175002 (2021)