Increased compression in HDC ablator implosions using a modified drive and capsule profile at the National Ignition Facility

Increased compression in HDC ablator implosions using a modified drive and capsule profile at the National Ignition Facility

Compression is essential to achieving high-gain in Inertial Confinement Fusion (ICF). However, increasing compression with crystalline ablator implosions has so far not been successful in experiments at the National Ignition Facility, attributed to increased hydrodynamic instability growth with higher compression designs. To address this, the recently proposed SQ-n design [1] replaces the second and third shock phase with a more gently ramped rise and also introduces doping of the ablator all of the way to the fuel-ablator boundary to reduce the inflight fuel adiabat and instability growth at both the ablation front and ablator-DT fuel interface [2,3] and hence promote increased compression. 

We present experimental results, using the SQ-n design, demonstrating record high compression of the stagnated fuel in indirectly-driven implosions at the NIF. The fuel compression has been increased by up to ~25%, compared to all other designs with HDC ablators [4]. We also measured significantly reduced ablator-ice mix at peak compression, supporting the hypothesis that increased compression can be due to improved hydrodynamic stability of the new design. These findings are critical to the path toward improved burnup fraction and higher gains in upcoming full-scale DT layered implosions on NIF [5]. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

 

[1] D. Clark et al., Physics of Plasmas 29, 052710 (2022).

[2] C. Weber et al., submitted to Phys. Rev. Lett. 

[3] A. Do et al., Phys. Rev. Lett. 129, 215003 (2022).

[4] R. Tommasini et al., submitted to Phys. Rev. Lett.

[5] H. Abu-Shawareb, et al., Phys. Rev. Lett. 129, 075001 (2022).