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Title: Laser imprint reduction for the critical-density foam buffered target driven by a relatively strong foot pulse at early stage of laser implosions

In order to reduce the effect of laser imprint in direct-drive ignition scheme a low-density foam buffered target has been proposed. This target is driven by a laser pulse with a low-intensity foot at the early stage of implosion, which heats the foam and elongates the thermal conduction zone between the laser absorption region and ablation front, increasing the thermal smoothing effect. In this paper, a relatively strong foot pulse is adopted to irradiate the critical-density foam buffered target. The stronger foot, near 1 × 10{sup 14 }W/cm{sup 2}, is able to drive a radiative shock in the low-density foam, which helps smooth the shock and further reduce the effect of laser imprint. The radiative shock also forms a double ablation front structure between the two ablation fronts to further stabilize the hydrodynamics, achieving the similar results to a target with a high-Z dopant in the ablator. 2D analysis shows that for the critical-density foam buffered target irradiated by the strong foot pulse, the laser imprint can be reduced due to the radiative shock in the foam and an increased thermal smoothing effect. It seems viable for the critical-density foam buffered target to be driven by a relatively strong foot pulse with themore » goal of reducing the laser imprint and achieving better implosion symmetry in the direct-drive laser fusion.« less
Authors:
;  [1] ;  [2] ;  [1] ; ;  [3]
  1. Key Lab of High Energy Density Physics Simulation, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)
  2. (China)
  3. Institute of Applied Physics and Computational Mathematics, P. O. Box 8009, Beijing 100094 (China)
Publication Date:
OSTI Identifier:
22489940
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABLATION; ABSORPTION; BUFFERS; DENSITY; FOAMS; HYDRODYNAMICS; IRRADIATION; LASER IMPLOSIONS; LASER RADIATION; LASER-RADIATION HEATING; PULSES; SYMMETRY; TARGETS; THERMAL CONDUCTION; THERMONUCLEAR IGNITION