Design of a two shock, high yield high-density carbon NIF target

In 2013, the first indirect drive exploding pusher (IDEP) targets were fielded on the NIF. These targets utilized a near-vacuum hohlraum (16 torr of helium) and thin (120 $\mu $m) GDP capsule with a short (4.5 ns) single shock drive. With long pulses, a hohlraum gas fill is typically needed to achieve symmetry. The short pulse of the IDEP permitted the usage of a near-vacuum hohlraum, which served to minimize laser-plasma interactions, such as cross beam transfer and backscatter, and achieved 99{\%} laser-hohlraum coupling. Both deuterium-deuterium and deuterium-tritium filled capsules produced high yields (approximately 5 x 10$^{\mathrm{12}}$ and 5 x 10$^{\mathrm{14}}$ neutrons, respectively) and were predicted well by HYDRA simulations with un-degraded laser drive. In addition, new experiments fielding high-density carbon (HDC) capsules in standard, gas-filled hohlraums have achieved the highest NIF neutron yields to-date. Combining and building upon these results, a two shock drive in a near-vacuum hohlraum with an HDC capsule has been developed. Challenges of the near-vacuum hohlraum, design of the two shock system, and first results will be discussed.