| Abstract Scope |
Tritium (T) retention in plasma-facing components raises radioactive concerns and reduces fuel availability in fusion devices. Understanding T behavior in tungsten (W), a leading armor material, is thus essential for fusion viability. In this work, we study hydrogen (as T surrogate) transport under thermal gradients in pure W, representative of divertor conditions with intense energy fluxes. We develop an analytical expression for the heat of transport (𝑄∗), parameterized using molecular dynamics simulations. 𝑄∗, a key parameter in irreversible thermodynamics, is shown to depend on temperature, thermal gradient, a characteristic length, and the jump rate ratio between hot and cold directions. We also show that, to first order, 𝑄∗ becomes independent of the gradient magnitude, consistent with MD results. Beyond hydrogen, we examine the thermally driven migration of vacancies and helium clusters, which are critical to fuel retention and material degradation. Our simulations provide insight into their coupling with temperature gradients. |