For ICF implosions that are x-ray driven, the hohlraum that drives the implosions develop a pole-hot x-ray field late in time due to plasma ingress. There are a number of approaches to mitigating this late-time drive (e.g., changing laser cone-fraction in time, altering cross-beam-energy transfer, altering hohlraum-capsule geometry) but these tactics have been pushed to their limits. In order to maintain control of ICF target implosion symmetry, which will enable higher fusion yields, a new solution is needed in target design.
This LLNL invention details a unique approach that involves the incorporation of a new geometry of spherical shine shields, which occupy a small volume above the north and south pole of the capsule early in time during the ICF implosion. Upon exposure to late-time hohlraum x-rays, they explode into a cloud of high atomic number (Z) material (e.g. gold or depleted uranium). This cloud of high-Z plasma will hinder the effects of the pole-hot drive, thus improved implosion symmetry is obtained.
• Simple modification to the hohlraum/target geometry that does not require pulse shape modifications
• A 70% increase in yield when spherical shine shields are utilized compared to current best in class solution that is reaching its maximum achievable yield potential
Novel high yielding target concepts for Inertial Fusion Energy (IFE)
Current stage of technology development:
TRL ☒ 0-2 ☐ 3-5 ☐ 5-9
LLNL has filed for patent protection on this invention.