1. Increasing hydrodynamic efficiency by reducing cross-beam energy transfer in direct-drive-implosion experiments.
- Author
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Froula DH, Igumenshchev IV, Michel DT, Edgell DH, Follett R, Glebov VY, Goncharov VN, Kwiatkowski J, Marshall FJ, Radha PB, Seka W, Sorce C, Stagnitto S, Stoeckl C, and Sangster TC
- Abstract
A series of experiments to determine the optimum laser-beam radius by balancing the reduction of cross-beam energy transfer (CBET) with increased illumination nonuniformities shows that the hydrodynamic efficiency is increased by ∼35%, which leads to a factor of 2.6 increase in the neutron yield when the laser-spot size is reduced by 20%. Over this range, the absorption is measured to increase by 15%, resulting in a 17% increase in the implosion velocity and a 10% earlier bang time. When reducing the ratio of laser-spot size to a target radius below 0.8, the rms amplitudes of the nonuniformities imposed by the smaller laser spots are measured at a convergence ratio of 2.5 to exceed 8 μm and the neutron yield saturates despite increasing absorbed energy, implosion velocity, and decreasing bang time. The results agree well with hydrodynamic simulations that include both nonlocal and CBET models.
- Published
- 2012
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