Collisionless Larmor Coupling of a laser plasma with a magnetized ambient plasma

POSTER

Abstract

We experimentally investigate the collisionless coupling leading to the cross-field acceleration and subsequent rotation of the ambient plasma during the perpendicular expansion of a laser-produced plasma in a magnetized background plasma.

In our experiment performed on the Large Plasma Device (LAPD), a super-alfvenic, laser-produced carbon plasma expands in a magnetized ambient helium plasma and forms a diamagnetic cavity. The streaming of the super-Alfvenic debris ions leads to the transverse energization of background helium ions via collisionless Larmor coupling. The magnetic fields are mapped out in 2D using a magnetic flux probe. The energized background plasma is observed and tracked using filtered self-emission of excited He+ ions at 468.6 nm, observed with filtered fast-gate imaging. Spatially and temporally resolved Doppler-shift spectroscopy shows that He+ ions are accelerated radially outward and then rotate in a motion consistent with Larmor coupling. Additionally, electric potential measurements with an emissive probe indicate that the transverse dynamics of the background ions cannot be explained by the electrostatic field.

*This work was supported by the Defense Threat Reduction Agency and Lawrence Livermore National Security LLC under contract number B661613.

Presenters

  • Lucas Rovige

    • University of California, Los Angeles

Authors

  • Lucas Rovige

    • University of California, Los Angeles

  • Robert S Dorst

    • University of California, Los Angeles

  • Ari Le

    • Los Alamos National Laboratory

  • Jessica Jean Pilgram

    • University of California, Los Angeles

  • Carmen G Constantin

    • University of California, Los Angeles

  • David Jeffrey Larson

    • Lawrence Livermore Natl Lab

  • Steve T Vincena

    • UCLA
    • University of California, Los Angeles

  • Shreekrishna Tripathi

    • University of California, Los Angeles
    • Department of Physics and Astronomy, University of California, Los Angeles
    • UCLA

  • Misa Cowee

    • Los Alamos National Laboratory

  • Derek B Schaeffer

    • University of California, Los Angeles
    • UCLA

  • Christoph Niemann

    • University of California, Los Angeles