J. B. Merlo, W. N. Rios-Lopez, K. Kawasaki, S. Gonzalez, L. B. Bayu Aji, A. M. Engwall, S. J. Shin, J. B. Forien, L. R. Sohngen, M. Seo, G. V. Taylor, S. O. Kucheyev, Lawrence Livermore National Laboratory, Livermore, CA
Advancing inertial confinement fusion (ICF) technology necessitates the development of innovative physical vapor deposition processes for fabricating millimeter-scale hollow spherical shells used as ICF ablators. Boron carbide (B_₄C) is the foremost candidate for the next generation of ICF ablators due to its unique properties. Its compatibility with direct-current magnetron sputtering (DCMS) further enables scalable production of ablators for inertial fusion energy (IFE) applications. Given the complexity of the deposition process—with its nonlinear dependence on various parameters and a large design space—the use of conventional optimization approaches is challenging. Therefore, the understanding of underlying deposition mechanisms is crucial for process refinement. Here, we will discuss our approach to developing the B_₄C deposition process via DCMS, focusing on the following two challenges of ultrathick coatings required for ICF and IFE applications: increasing coating rates and achieving process stability for prolonged deposition runs.