The Material Plasma Exposure eXperiment: Mission and conceptual design

•New linear plasma device MPEX will address plasma material interaction gaps for fusion.•MPEX will have increased capabilities over existing linear plasma devices and will be world-leading when completed.•MPEX will expose apriori neutron irradiated material samples for fusion reactor divertor relevant heat and particle fluxes.•The conceptual design of MPEX is finished. Mastering Plasma Material Interactions (PMI) is key for obtaining a high performance, high duty-cycle and safe operating fusion reactor. Numerous gaps exist in PMI which have to be addressed before a reactor can be built. In particular the lack of data at high ion fluence, fusion reactor divertor relevant plasma conditions and neutron displacement damage requires new experimental devices to be able to develop plasma facing materials and components. This has been recognized in the community and the U.S. fusion program is addressing this need with a new linear plasma device—the Material Plasma Exposure eXperiment (MPEX). MPEX will be a superconducting linear plasma device with magnetic fields of up to 2.5 T. The plasma source is a high-power helicon source (200 kW, 13.56 MHz). The electrons will be heated via Electron Bernstein Waves with microwaves using multiple 70 GHz gyrotrons (up to 600 kW in total). Ions will be heated via ion cyclotron heating in the so-called “magnetic beach heating” scheme in the frequency range of 6−9 MHz (up to 400 kW in total). An overview of the conceptual design and the project/design requirements is given.