Thermal Cycling Stresses in W‐Monofilament Reinforced Copper

Abstract

New materials have to be developed for fusion reactor systems to withstand the high thermal load and heavy irradiation under service conditions. The divertor element collects the residuals of the nuclear reaction and withdraws heat from the reaction chamber into a heat sink. A thermal flux of ≈20 W mK−1 can be expected in such components. A plasma facing W plate is attached to a CuCrZr heat sink suffering CTE mismatch stresses at the interface due to pulsed operation required for the Tokamak reactor design. Fiber reinforced metal matrix composites are applied as an interlayer to reduce macroscopic interfacial stresses in these components. W‐wire reinforced copper is a promising material for this application due to a good fiber‐matrix bonding strength which is further increased by surface etching or graded interface designs. Thermal stresses in between the matrix and the wires are responsible for thermal fatigue damage within the constituents and at their interface. Neutron and synchrotron diffraction was performed in situ during thermal cycling to determine the micro stress amplitudes and their changes under simulated service conditions.

Thermal fatigue damage in monofilament reinforced copper for heat sink applications in divertor elements

“…(2c) and (e long = (d À d trans )/d trans ) to produce comparable results. Convergence of both neutron and synchrotron results obtained for W wires verified the unaxial approach [16].…”

“…A simple uniaxial strain state assumption relative to W powder reference scans was made using Eq. (2c) with (e long = (d À d 0 )/d 0 and e trans = 0) [16]. The calculations delivered relative results to compare fiber bonding qualities.…”