Enhancements in Laser-Direct-Drive Nuclear Performance with Target Radius

Inertial confinement fusion is likely to require significant improvements in technology and design for large targets to implode at high driver energies. To assess the potential for benefits, we report on nuclear performance as a function of target radius R_{t} in direct-drive cryogenic implosions as performed on the OMEGA laser. The neutron yield and areal density are found to increase as R_{t}^{5.0±0.2} and R_{t}^{1.8±0.2}, respectively, and exhibit a much stronger dependence on target radius than previous studies have assumed. As this Letter demonstrates, these types of sensitivities should be expected when implosions are unstable, and have been degraded by a range of multidimensional effects in 3D. If the imperfections in a target and laser system are fixed in magnitude, it follows that larger implosions have higher relative quality, and approach criteria to ignite much more quickly than commonly appreciated.