RustBCA: A High-Performance Binary-Collision-Approximation Code for Ion-Material Interactions

Abstract

Ion-material interactions are of vital importance in industrial applications, the study and design of nuclear fusion devices, the engineering of survivable spacecraft components, and more. In particular, plasma-material interactions are typically dominated by ion-material interactions, including the phenomena of sputtering, reflection, and implantation. These phenomena are difficult to model analytically, and many such models rely on empirical or semi-empirical formulas , such as the Yamamura sputtering yield formula (Y. Yamamura, 1982), or the Thomas reflection coefficient (Thomas et al., 1992). However, such models are inherently limited, and of little applicability to complex geometry, multi-component surfaces, or for coupling to plasma or material dynamics codes. Since ion-material interactions span a range of energies from sub-eV to GeV and beyond, n-body approaches such as molecular dynamics can be com-putationally infeasible for many applications where the characteristic ion range exceeds the limits of reasonable molecular dynamics domains. Instead, approximations to the full n-body problem are used; the most common of these is the Binary Collision Approximation (BCA), a set of simplifying assumptions to the full n-body problem. RustBCA is a high-performance, general purpose, ion-material interactions BCA code, built for scientific flexibility and ease of use. RustBCA features include: • Electronic stopping formulations for low energy (up to 25 keV/nucleon) and high energy (up to 1 GeV/nucleon) • Kr-C, ZBL, Moliere, and Lenz-Jensen screened coulomb interatomic potentials • Lennard-Jones and Morse attractive-repulsive potentials • The unique capability of using multiple interatomic potentials in a single simulation • Choice of Gaussian quadrature or the approximate MAGIC algorithm for determining scattering angles • Full trajectory tracking of ions and material atoms, including local nuclear and electronic energy losses • A human-and machine-readable configuration file • Full 6D output of all particles that leave the simulation (via sputtering or reflection) • Multiple geometry types