Vortex Dynamics in Inertial Fusion and Astrophysics

The mixing induced by a shock wave passing through a fluid interface can stimulate the ejection of high-velocity projectiles of one fluid into the other, which severely disrupt implosion symmetry in inertial confinement fusion and transport stellar core elements during supernovae. Recent improvements in experimental diagnostics and numerical simulations reveal that such projectiles share key characteristics with classical fluid vortex rings, thus enabling a path to understand their dynamics. In the first part of the talk, we examine recent efforts to isolate the ejection of vortex rings from shocked interfaces and determine their scaling through numerical simulations and physical experiments. We find that the strength of the rings expectedly scales with the intensity of density and pressure gradients but saturates beyond a critical protrusion size, enabling an a priori prediction of the energy transported by vortex rings in inertial confinement fusion and supernovae.

Widening our focus by nearly twenty orders of magnitude in length scale, vortex dynamics may also play a critical role in circumstellar environments, including that which surrounded the progenitor of Supernova 1987A (SN1987A). Because of its recency and proximity to Earth, SN1987A is a critical source of data constraining of our understanding of stellar evolution. The circumstellar environment surrounding SN1987A consists of evenly spaced gaseous clumps comprising an equatorial ring predating the supernova. Our analysis suggests that the ring could have formed a vortex dipole unstable to the Crow instability, well known in aeronautics for dissipating airplane wakes, after acquiring vorticity from the progenitor wind, with a dominant wavenumber remarkably consistent with the number of observed clumps. Recent observations by the James Webb Space Telescope further confirm the plausibility that the Crow instability induced clump formation. Beyond SN1987A, the same mechanism may affect other circumstellar environments, including protoplanetary disks. We conclude with a discussion of ongoing work to examine this instability mechanism, which may play a role in seeding planet formation, experimentally