Observation of Weibel magnetic fields in laser-produced interpenetrating flows

Abstract Weibel instability is a promising candidate mechanism for collisionless shock formation in astrophysical systems. Capturing the underlying physics of Weibel instability will help us to understand the astrophysical shock formation, magnetic field generation and amplification, particle acceleration, and so on. Laboratory astrophysics, provides a new way to study these microphysics in controlled conditions. At Shenguang-II laser facility, the interpenetrating plasma flows are generated by eight laser beams irradiating a pair of opposing foils to mimic the supernova explosion and the ejecta sweeping up the surrounding medium. Evolution of collisionless interpenetrating plasma flows is observed using optical diagnostics. Filamentary structures appear in the interaction region and the associated magnetic strength is measured about 40 T. Theoretical analysis and simulations indicate that these characteristics are induced by nonlinear Weibel instability.