High Heat Flux Testing Facilities and an Electrothermal-Arc Plasma Source for Plasma-Material Interaction Studies and Diagnostic Development

Tokamak plasma-facing components experience significant stresses from plasma-material interactions (PMI) due to cyclic high thermal loads, plasma exposure, and neutron irradiation. As the field progresses to reactor-level power fluxes, the harsh fusion environment demands much of plasma-facing materials.

Chapter 1 introduces plasma-material interactions and the condition plasma-facing components are expected to endure. While plasma exposure and neutron radiation damage are introduced, the synergistic effects of cyclic high thermal loads under plasma exposure are focused on. This motivates the need for plasma-facing materials studies.

Chapter 2 gives a brief overview of many high heat flux test facilities worldwide. Three prominent high heat flux devices are discussed, including (1) the linear plasma device Magnum-PSI, (2) the electron beam facility JUDITH-II, and (3) the electrothermal-arc plasma source SIRENS. This motivates the high heat flux testing of materials in a highly controlled, repeatable, transient-level plasma exposure and plasma heat flux conditions. This is the motivation for the project undertaken at Oak Ridge National Laboratory.

Chapter 3 is the project undertaken and is the main focus of this report. At Oak Ridge National Laboratory, an electrothermal-arc plasma source (ET-Arc) was modified and rebuilt in the laser diagnostics lab. The motivation for this project is twofold: (1) to develop two laser diagnostics, a “Portable Diagnostic Package” (PDP) which characterizes the plasma spectroscopically and Digital Holography (DH) which measures the in situ erosion of the target; and (2) to use the ET-Arc source and DH to conduct erosion studies under transient-level (~GW m^-2) heat fluxes. The modifications, upgrades, and diagnostic capabilities are discussed as well as future work.

This is a project-based thesis, or report, for a Masters of Science in Nuclear Engineering.