An experimental and simulation study of warm dense carbon foams at ambient density(ne∼10^(21) cm^(−3))is presented.This study of isochorically heated foams is motivated by their potential application in carbon-atmosp...An experimental and simulation study of warm dense carbon foams at ambient density(ne∼10^(21) cm^(−3))is presented.This study of isochorically heated foams is motivated by their potential application in carbon-atmosphere white-dwarf envelopes,where there are modeling uncertainties due to the equation of state.The foams are heated on an approximately picosecond time scale with a laser-accelerated proton beam.The cooling and expansion of the heated foams can be modeled with appropriately initialized radiation-hydrodynamics codes;xRAGE code is used in this work.The primary experimental diagnostic is the streaked optical pyrometer,which images a narrow band of radiation from the rear surface of the heated material.Presented are xRAGE modeling results for both solid aluminum targets and carbonized resorcinol-formaldehyde foam targets,showing that the foam appears to cool slowly on the pyrometer because of partial transparency.So that simulations of cooling foam are processed properly,it is necessary to account for finite optical depth in the photosphere calculation,and the methods for performing that calculation are presented in depth.展开更多
基金This work was supported by NNSA cooperative Agreement Grant No.DE-NA0002008the DARPA PULSE program(No.12-63-PULSE-FP014)+2 种基金the Air Force Office of Scientific Research(Grant No.FA9550-14-1-0045)This work was performed under the auspices of the U.S.Department of Energy by the Triad National Security,LLC(Contract No.89233218CNA000001)Los Alamos National Laboratory and was supported by the LANL Office of Experimental Sciences programs.Simulations were run on the LANL Institutional Computing Clusters.
文摘An experimental and simulation study of warm dense carbon foams at ambient density(ne∼10^(21) cm^(−3))is presented.This study of isochorically heated foams is motivated by their potential application in carbon-atmosphere white-dwarf envelopes,where there are modeling uncertainties due to the equation of state.The foams are heated on an approximately picosecond time scale with a laser-accelerated proton beam.The cooling and expansion of the heated foams can be modeled with appropriately initialized radiation-hydrodynamics codes;xRAGE code is used in this work.The primary experimental diagnostic is the streaked optical pyrometer,which images a narrow band of radiation from the rear surface of the heated material.Presented are xRAGE modeling results for both solid aluminum targets and carbonized resorcinol-formaldehyde foam targets,showing that the foam appears to cool slowly on the pyrometer because of partial transparency.So that simulations of cooling foam are processed properly,it is necessary to account for finite optical depth in the photosphere calculation,and the methods for performing that calculation are presented in depth.
