The Plasma‐Materials Interactions Test Facility (PMITF) recently designed and constructed at Oak Ridge National Laboratory (ORNL) is an electron cyclotron resonance microwave plasma system with densities around 1011cm−3and electron temperatures of 10–20 eV. The device consists of a mirror cell with high‐field‐side microwave injection and a heating power of up to 0.8 kW (cw) at 2.45 GHz. The facility will be used for studies of plasma‐materials interactions and of particle physics in pump limiters and for development and testing of plasma edge diagnostics.