Asymmetric Direct-Drive Spherical Implosions to Study Combined Effects of Asymmetry and Mixing

Implosions of direct-drive capsules with symmetric drive and controlled asymmetries with P_2 ∼10%--15% are created and studied with both neutron and x-ray imaging perpendicular to the axis of asymmetry. Our general goal is to understand the combined effects of imposed asymmetry and mixing on implosions. Fill pressures of 10 atm and 5 atm have been used to achieve convergence ratios of 10--20 and correspondingly greater asymmetry of the imploded capsule for the same drive asymmetry. Neutron yields and burn temperatures, time-dependent burn history and bang time, and the neutron and x-ray images are all used to diagnose the mixing between the pusher (glass or plastic) and DT gas. Both pinhole and penumbral aperture occluders have been used for the neutron imaging. The experimental design and diagnostic layout will be presented, as well as the achieved laser conditions and asymmetry of the drive.