Deceleration-stage Rayleigh–Taylor growth in a background magnetic field studied in cylindrical and Cartesian geometries

Experiments have identi fi ed the Rayleigh – Taylor (RT) instability as one of the greatest obstacles to achieving inertial con fi nement fusion. Consequently, mitigation strategies to reduce RT growth and fuel – ablator mixing in the hotspot during the deceleration phase of the implosion are of great interest. In this work, the effect of seed magnetic fi elds on deceleration-phase RT growth are studied in planar and cylindrical geometries under conditions relevant to the National Ignition Facility (NIF) and Omega experiments. The magnetohydrodynamic (MHD) and resistive-MHD capabilities of the FLASH code are used to model imploding cylinders and planar blast-wave-driven targets. Realistic target and laserparametersarepresentedthatsuggesttheoccurrenceofmorphologicaldifferencesinlate-timeRTevolutioninthecylindricalNIFcaseandameasurabledifferenceinspikeheightofsingle-modegrowthintheplanarNIFcase.TheresultsofthisstudyindicatetheneedfortargetdesignstoutilizeanRT-unstablefoam – foam interface in order to achieve suf fi cient magnetic fi eld ampli fi cation to alter RT evolution. Benchmarked FLASH simulations are used to study these magnetic fi eld effects in both resistive and ideal MHD. on the hotspot. The deceleration phase when the interior begins pushing back on the