Abstract
The Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) is a linear plasma device to test the plasma source concepts for the future Material Plasma Exposure eXperiment (MPEX). MPEX is planned to address plasma material interactions under fusion reactor divertor conditions as will occur in devices like DEMO, including the plasma exposure of a-priori neutron irradiated materials. This requires a novel linear plasma device with a plasma source that can produce high electron densities along with heating systems to obtain high electron and ion temperatures. In Proto-MPEX a high-power helicon source was tested together with electron heating (28 GHz microwaves) and ion cyclotron heating (8.5–12 MHz). Electron densities in excess of 1 × 1020 m−3 were produced with the helicon antenna. Electron temperatures can reach 20 eV and are typically below 6 eV at high densities (>5 × 1019 m−3). Ion heating has been demonstrated at low electron densities (<2 × 1019 m−3) with ion temperatures of up to 13 eV. Maximum heat fluxes of 14 MW/m2 have been obtained in low density discharges (∼ 5 × 1018 m−3), while heat fluxes are typically only 2–3 MW/m2 in high density discharges (>2 × 1019 m−3).
