Hydrodynamic instability experiments with three-dimensional modulations at the National Ignition Facility

作     者：V.A.Smalyuk S.V.Weber D.T.Casey D.S.Clark J.E.Field S.W.Haan A.V.Hamza D.E.Hoover O.L.Landen A.Nikroo H.F.Robey C.R.Weber 

作者机构：Lawrence Livermore National Laboratory NIF Directorate General Atomics 

出 版 物：《High Power Laser Science and Engineering》 (高功率激光科学与工程（英文版）)

年 卷 期：2015年第3卷第2期

页      面：1-8页

核心收录：

学科分类：08[工学] 082701[工学-核能科学与工程] 0827[工学-核科学与技术] 

基　　金：performed under the auspices of the U.S.Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 

主　　题：Hydrodynamic instabilities 

摘      要：The first hydrodynamic instability growth measurements with three-dimensional(3D) surface-roughness modulations were performed on CH shell spherical implosions at the National Ignition Facility(NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841(2004)]. The initial capsule outer-surface amplitudes were increased approximately four times, compared with the standard specifications, to increase the signal-to-noise ratio, helping to qualify a technique for measuring small 3D modulations. The instability growth measurements were performed using x-ray through-foil radiography based on time-resolved pinhole imaging. Averaging over 15 similar images significantly increased the signal-to-noise ratio, making possible a comparison with 3D simulations. At a convergence ratio of～2.4, the measured modulation levels were～3 times larger than those simulated based on the growth of the known imposed initial surface modulations. Several hypotheses are discussed, including increased instability growth due to modulations of the oxygen content in the bulk of the capsule. Future experiments will be focused on measurements with standard 3D ‘nativeroughness capsules as well as with deliberately imposed oxygen modulations.