Perpendicular shock structure in experiments relevant to space and astrophysical plasma

TOK Seminar

  • Datum: 08.11.2022
  • Uhrzeit: 12:30 - 13:30
  • Vortragende(r): Danny R Russell
  • Imperial College London
  • Ort: IPP Garching
  • Raum: Seminarraum L5 und Zoom
  • Gastgeber: IPP
  • Kontakt: daniel.told@ipp.mpg.de

Shock waves are ubiquitous in astrophysical, space and laboratory plasmas and often include an embedded, dynamically significant magnetic field. The theoretical understanding of magneto-hydrodynamic shocks was established in the 1950s. However, certain aspects of the theory, including shock structure, heating and particle acceleration, have not been tested in the laboratory. This talk will discuss two laboratory investigations of shocks at the MAGPIE pulsed power facility (1.4 MA, 250 ns rise time) at Imperial College London.

Firstly, we present a study of collisional subcritical shocks, a class of shock in which viscous dissipation is absent and the shock is formed by magnetic or thermal transport. We show agreement with two theoretical predictions of the shock structure which have not previously been demonstrated. These are: the absence of an isomagnetic jump at the shock front and that the shock width is equal to the resistive diffusion length [1]. The experiments were diagnosed using optical Thomson scattering, laser interferometry, Faraday rotation imaging and optical self-emission imaging. We discuss the link between these results and recent in situ measurements of the interstellar medium [2] as well as potential consequences for astrophysical observation.

The second part of this talk will discuss laser driven magnetised collisionless shocks. Collisionless shocks are known to be particle accelerators in astrophysical systems. We present experimental results demonstrating the feasibility of studying such shocks at a pulsed power facility and discuss scaling these experiments to larger experimental facilities.

[1] D. R. Russell et al in prep. https://arxiv.org/abs/2201.09039

[2] L. F. Burlaga et al 2013 ApJL 778 L3

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