Hybrid C Campaign: Optimizing Implosions With CH Ablators at the National Ignition Facility*

Recent work on ICF implosions using CH ablators at the National Ignition Facility (NIF) includes key optimizations relevant to not just CH implosions, but also to implosions with other ablators, such as HDC and Be.  Utilizing low levels of wavelength separation between the inner and outer beams, i.e., cross-beam energy transfer at low values of Δλ ~ 1 Å, the Hybrid C campaign has demonstrated a change in P2 symmetry from oblate to prolate of over 20 µm, corresponding to an increase in inner beam intensity by a factor of 1.3.  Energy coupling remains high (> 97%), with low levels of backscatter, SBS fluence, and hot electrons. 

The capsule is further optimized in two ways.  First, capsule dopant levels (Si) will increase, to further shield against M-band at high power (see talk by T. Döppner, LLNL).  Also, to reduce oxygen uptake (S. Ali, PoP, May, 2018) the capsule is flash coated with aluminum. Results from the Hybrid C campaign will be presented along with future plans to explore generic optimization strategies.  A design for a scale-up in capsule size by a factor of 1.1 will also be discussed.