Supersonic plasma turbulence in the laboratory

White, T. G. and Oliver, M. T. and Mabey, P. and Kühn-Kauffeldt, M. and Bott, A. F. A. and Döhl, L. N. K. and Bell, A. R. and Bingham, R. and Clarke, R. and Foster, J. and Giacinti, G. and Graham, P. and Heathcote, R. and Koenig, M. and Kuramitsu, Y. and Lamb, D. Q. and Meinecke, J. and Michel, Th. and Miniati, F. and Notley, M. and Reville, B. and Ryu, D. and Sarkar, S. and Sakawa, Y. and Selwood, M. P. and Squire, J. and Scott, R. H. H. and Tzeferacos, P. and Woolsey, N. and Schekochihin, A. A. and Gregori, G. (2019) Supersonic plasma turbulence in the laboratory. Nature Communications, 10. 1758. ISSN 2041-1723 (https://doi.org/10.1038/s41467-019-09498-y)

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Abstract

The properties of supersonic, compressible plasma turbulence determine the behavior of many terrestrial and astrophysical systems. In the interstellar medium and molecular clouds, compressible turbulence plays a vital role in star formation and the evolution of our galaxy. Observations of the density and velocity power spectra in the Orion B and Perseus molecular clouds show large deviations from those predicted for incompressible turbulence. Hydrodynamic simulations attribute this to the high Mach number in the interstellar medium (ISM), although the exact details of this dependence are not well understood. Here we investigate experimentally the statistical behavior of boundary-free supersonic turbulence created by the collision of two laser-driven high-velocity turbulent plasma jets. The Mach number dependence of the slopes of the density and velocity power spectra agree with astrophysical observations, and supports the notion that the turbulence transitions from being Kolmogorov-like at low Mach number to being more Burgers-like at higher Mach numbers.