D. C. Goodelman, G. V. Taylor, E. Kim, A. M. Engwall, S. J. Shin, L. R. Sohngen, J. B. Merlo, D. J. Strozzi, B. J. Bocklund, S. O. Kucheyev, L. B. Bayu Aji, Lawrence Livermore National Laboratory, Livermore CA
The design of next-generation hohlraums requires careful material selection criteria, such that the hohlraum exhibits high density, high electrical resistivity for magnetically-assisted ICF considerations, structural robustness, low reactivity, toxicity, and radioactivity, and higher x-ray drive efficiency compared to conventionally used hohlraum materials. Through Lasnex simulations, we have identified the TaWAuBi high entropy alloy system as a potential candidate to satisfy these criteria. We have systematically studied the deposition of this alloy system, first through combinatorial magnetron sputtering to study the role of constituent elements on microstructure and physical properties, and then by evaluating the role of working pressure, substrate cooling, and deposition mode on the microstructure when depositing from a single, powder-pressed sputtering source. Our results reveal that RF magnetron sputtering coupled with a low working pressure and substrate cooling to RT results in the highest quality microstructures. We then demonstrate deposition of Ta1W1Au1Bi7 hohlraums onto rotating sphero-cylindrical mandrels, paving the way to produce next-generation, high entropy alloy hohlraums.

This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344 and was supported by the LLNL LDRD program under project No. 23-ERD-005