Isotopic fractionation and reaction kinetics in nuclear fusion plasmas for optimized power generation

Abstract

Nuclear reaction rates and energy production are strongly influenced by the behavior of hydrogen isotopes in high-temperature fusion plasmas. The chemical mechanisms controlling isotopic redistribution remain largely unexplored, limiting predictive management of D–T interactions and fuel consumption despite reactor advancements. This research addresses this gap by developing a chemically rigorous framework to quantify isotope-dependent reaction kinetics and fractionation under fusion-relevant conditions. Atomic, ionic, and molecular species, isotope-sensitive collisional and recombination processes, and surface-mediated boundary interactions are incorporated into a comprehensive plasma chemical kinetic model. Partition functions, equilibrium populations, and fractionation factors are evaluated via thermochemical modeling, while reaction rate constants are determined using transition state theory (TST) with isotope-specific mass corrections, augmented by quantum tunneling and reduced mass scaling. Simulations reveal pronounced kinetic isotope effects, non-equilibrium isotopic segregation, and region-specific D/T variations that modulate local fusion power density. The delineation of thermodynamic versus kinetic control regimes highlights the critical crossover for optimal fuel burn-up. Integrating isotope-sensitive kinetics into reactor control and plasma-facing material design demonstrates a predictive pathway for maximizing energy output and fuel efficiency. The study establishes the first molecular-level framework linking plasma chemistry to macroscopic fusion performance, providing a foundation for next-generation D–T reactor optimization.

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