Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas

Sudipta Mondal, V. Narayanan, Wen Jun Ding, Amit D. Lad, Biao Hao, Saima Ahmad, Wei Min Wang, Zheng-Ming Sheng, Sudip Sengupta, Predhiman Kaw, Amita Das, G. Ravindra Kumar

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Abstract

Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (1018W/cm2) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy “hot” electrons created by the laser pulse and “cold” return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments.
Original languageEnglish
Pages (from-to)8011-8015
Number of pages5
JournalProceedings of the National Academy of Sciences
Volume109
Issue number21
Early online date7 May 2012
DOIs
Publication statusPublished - 2012

Keywords

  • direct observation
  • turbulent magnetic fields
  • hot
  • laser produced plasmas
  • dense

Cite this

Mondal, S., Narayanan, V., Ding, W. J., Lad, A. D., Hao, B., Ahmad, S., Wang, W. M., Sheng, Z-M., Sengupta, S., Kaw, P., Das, A., & Kumar, G. R. (2012). Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas. Proceedings of the National Academy of Sciences , 109(21), 8011-8015. https://doi.org/10.1073/pnas.1200753109