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The spark of the Super: Teller–Ulam and the birth of the H-bomb—rivalry, credit, and legacy at 75 years
In early 1951, Los Alamos scientists Edward Teller and Stanislaw Ulam devised a breakthrough that would lead to the hydrogen bomb [1]. Their design gave the United States an initial advantage in the Cold War, though comparable progress was soon achieved independently in the Soviet Union and the United Kingdom.
Samuel Olivier, Terry S. Haut
Nuclear Science and Engineering | Volume 198 | Number 6 | June 2024 | Pages 1179-1214
Research Article | doi.org/10.1080/00295639.2023.2238171
Articles are hosted by Taylor and Francis Online.
We present high-order, finite element–based Second Moment Methods (SMMs) for solving radiation transport problems in two spatial dimensions. We leverage the close connection between the Variable Eddington Factor (VEF) method and SMM to convert existing discretizations of the VEF moment system to discretizations of the SMM moment system. The moment discretizations are coupled to a high-order Discontinuous Galerkin discretization of the SN transport equations. We show that the resulting methods achieve high-order accuracy on high-order (curved) meshes, preserve the thick diffusion limit, and are effective on a challenging multimaterial problem both in outer fixed-point iterations and in inner preconditioned iterative solver iterations for the discrete moment systems. We also present parallel scaling results and provide direct comparisons to the VEF algorithms from which the SMM algorithms were derived.