Princeton Plasma Physics Laboratory (PPPL) Colloquium

As fusion enters a phase aiming at harnessing fusion energy, new plasma facing materials (PFMs) and components that are able to withstand the harsh conditions of fusion reactors need to be developed. Solution are needed for PFMs to be irradiation-resistant and erosion-resistant over long operation durations. The capabilities to test PFMs under fusion prototypic conditions do not currently exist. The linear plasma device Material Plasma Exposure eXperiment (MPEX) will close this gap by exposing apriori neutron-irradiated materials to fusion reactor prototypic divertor plasma conditions. This is achieved with a novel plasma source and heating concept, which makes use of a high-power helicon (200 kW, 13.56 MHz) to create a high-density plasma which will be heated by waves in the electron cyclotron resonance frequency range (400 kW, 70/105 GHz) and in the ion cyclotron resonance frequency range (400 kW, 6-9 MHz). This concept should allow reaching electron and ion temperatures of up to 15 eV, electron densities of up to 10 21 m -3 and parallel heat fluxes of up to 40 MW/m 2 in front of the target. The device will operate in steady-state and make use of superconducting magnets to reach the required magnetic fields of 1 T at the target. A surface-analysis station, which will allow in-vacuo analysis with a large set of surface diagnostic tools, is an integral part of MPEX. This presentation will focus on the physics basis of MPEX based on results obtained with the frontrunner experiment Proto-MPEX. A first research plan has been developed, focusing on urgent plasma material interactions science research questions and the high-level commissioning to bring MPEX to its full performance including the capability to expose activated materials and the ability to run high-fluence discharges of up to 10 6 seconds. This research and high-level commissioning plan will be presented.