Application of the heat balance for estimating the hydrogen dissociation rate constant on the tantalum surface

Heat transfer between the surface of a heated wire and ambient gas within the framework of the two-step mechanism of heterogeneous dissociation of hydrogen is studied by the Direct Simulation Monte Carlo method. This mechanism includes four heterogeneous reactions and takes into account the occupancy of activation sites on the surface. Based on the heat balance analysis performed, a dissociation rate constant is proposed, which yields the values of the power spent on gas heating and heterogeneous reactions that coincide with experimental data. The influence of the dissociation rate constant on the occupancy of surface sites and also on the probabilities of dissociation, recombination, and adsorption due to particle-surface collisions is analyzed.