Publication Date:
2015-12-11
Description:
Experimental results from indirectly driven ignition implosions during the National Ignition Campaign (NIC) [M. J. Edwards et al ., Phys. Plasmas 20 , 070501 (2013)] achieved a record compression of the central deuterium-tritium fuel layer with measured areal densities up to 1.2 g/cm 2 , but with significantly lower total neutron yields (between 1.5 × 10 14 and 5.5 × 10 14 ) than predicted, approximately 10% of the 2D simulated yield. An order of magnitude improvement in the neutron yield was subsequently obtained in the “high-foot” experiments [O. A. Hurricane et al ., Nature 506 , 343 (2014)]. However, this yield was obtained at the expense of fuel compression due to deliberately higher fuel adiabat. In this paper, the design of an adiabat-shaped implosion is presented, in which the laser pulse is tailored to achieve similar resistance to ablation-front instability growth, but with a low fuel adiabat to achieve high compression. Comparison with measured performance shows a factor of 3–10× improvement in the neutron yield (〉40% of predicted simulated yield) over similar NIC implosions, while maintaining a reasonable fuel compression of 〉1 g/cm 2 . Extension of these designs to higher laser power and energy is discussed to further explore the trade-off between increased implosion velocity and the deleterious effects of hydrodynamic instabilities.
Print ISSN:
1070-664X
Electronic ISSN:
1089-7674
Topics:
Physics
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