Speaker
Description
The Weibel instability is a candidate mechanism for the generation of astrophysical seed fields: PIC simulations suggest that Weibel-generated fields might scale much more favorably for long length scales (B ∝ λ^0) than the Biermann-generated fields (B ∝ λ^-1). This possibility, however, requires a mechanism to explain how Weibel field structures grow to large length scales. Existing theory and simulations provide models whose predictions differ substantially depending on the included physics: one model [C. Ruyer et al., Physics of Plasmas 22, 032102 (2015)] predicts filament wavelengths grow as λ ∝ t^2, while another model [M. Zhou, et al., Phys. Rev. Res. 1, 012004 (2019)] predicts λ ∝ t^(1/2) (for asymptotically late times t). Instabilities could play a role at disrupting the late-time evolution of Weibel filaments, which would change the temporal evolution of filaments. Presented in this work are new OMEGA experimental measurements at later times than previously observed. A comprehensive set of proton radiography measurements are used to capture filament evolution over a large field of view and Thomson scattering records the plasma conditions and sub-filament structure, with the objective of determining which model best matches the late-time filament dynamics.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.