Performance of indirectly driven capsule implosions on NIF using adiabat-shaping

[摘要] A series of indirectly driven capsule implosions has been performed on the National Ignition Facility to assess the relative contributions of ablation-front instability growth vs. fuel compression on implosion performance. Laser pulse shapes for both low and high-foot pulses were modified to vary ablation-front growth & fuel adiabat, separately and controllably. Two principal conclusions are drawn from this study: 1) It is shown that an increase in laser picket energy reduces ablation-front instability growth in low-foot implosions resulting in a substantial (3-10X) increase in neutron yield with no loss of fuel compression. 2.) It is shown that a decrease in laser trough power reduces the fuel adiabat in high-foot implosions results in a significant (36%) increase in fuel compression together with no reduction in neutron yield. These results taken collectively bridge the space between the higher compression low-foot results and the higher yield high-foot results.

[发布机构] Lawrence Livermore National Laboratory, Livermore; CA; 94551, United States^1;General Atomics, San Diego; CA; 92186, United States^2;Laboratory for Laser Energetics, Rochester; NY; 14623, United States^3;Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge; MA; 02139, United States^4

[关键词] Ablation fronts;Higher yield;Instability growth;National ignition facility;Neutron yields;NO reduction;Relative contribution;Space between