Autori: Stoeckl C, Chiritescu C, Delettrez JA, Epstein R, Glebov VY, Harding DR, Keck RL, Loucks SJ, Lund LD, McCrory RL, McKenty PW, Marshall FJ, Meyerhofer DD, Morse SFB, Regan SP, Radha PB, Roberts S, Sangster TC, Seka W, Skupsky S, Smalyuk VA, Sorce C, Soures

Editorial: PHYSICS OF PLASMAS, 9 (5), p.2195-2201, 2002.

Rezumat:

Initial results from direct-drive spherical cryogenic target implosions on the 60-beam OMEGA laser system [T. R. Boehly, D. L. Brown, R. S. Craxton , Opt. Commun. 133, 495 (1997)] are presented. These experiments are part of the scientific base leading to direct-drive ignition implosions planned for the National Ignition Facility (NIF) [W. J. Hogan, E. I. Moses, B. E. Warner , Nucl. Fusion 41, 567 (2001)]. Polymer shells (1-mm diam with walls <3 mum) are filled with up to 1000 atm of D-2 to provide 100-mum-thick ice layers. The ice layers are smoothed by IR heating with 3.16-mum laser light and are characterized using shadowgraphy. The targets are imploded by a 1-ns square pulse with up to similar to24 kJ of 351-nm laser light at a beam-to-beam rms energy balance of <3% and full-beam smoothing. Results shown include neutron yield, secondary neutron and proton yields, the time of peak neutron emission, and both time-integrated and time-resolved x-ray images of the imploding core. The experimental values are compared with 1-D numerical simulations. The target with an ice-layer nonuniformity of σ(rms)=9 μm showed 30% of the 1-D predicted neutron yield. These initial results are encouraging for future cryogenic implosions on OMEGA and the NIF.

Cuvinte cheie: physics of plasmas, including magnetofluid mechanics, kinetic theory and statistical mechanics of fully and partially ionized gases