SUMMARY

The divertor is a critical component in magnetic fusion energy reactor designs that separates the core burning plasma from plasma-material interactions and removes residual impurities from the core. However, as one of the few solid surfaces directly exposed to the plasma, divertors are subject to very high steady-state heat fluxes, projected to be at least 10 MW/m2. The helium-cooled modular divertor with multiple jets (HEMJ), which cools the back of the plasma-facing surface with an array of impinging jets of helium, is currently the leading candidate for the European Union demonstration fusion power plant (DEMO). This proposed doctoral thesis will experimentally and numerically evaluate the thermal-hydraulic performance of the HEMJ over a range of parameters including typical operating conditions, and optimize the geometry of the HEMJ in terms of its thermal-hydraulic performance. Experiments were conducted on a test section that closely simulates the HEMJ geometry in a helium loop operating at prototypical pressures of ~10 MPa. Experimentally obtained heat transfer coefficients and pressure drops were converted to dimensionless Nusselt numbers and loss coefficients. A numerical model developed in a commercial computational fluid dynamics software package was validated against experimental data and used to investigate the effects of varying the jet impingement distance and the jet parameters.