The EU DEMO equatorial outboard limiter - Design and port integration concept

The equatorial outboard limiters (also called outboard midplane limiters (OMLs)) are an essential part of the DEMO wall protection concept. Limiters are foreseen in different areas of the DEMO first wall, namely in the equatorial ports, on the high-field side, in vertical ports and additional protection limiters between equatorial and lower ports. The limiters shall prevent the plasma to touch the first wall of the breeding blankets during all plasma transients. The port integration concept of the OMLs, used for plasma ramp-up/-down, is explained including (i) thermal, structural and electromagnetic loads, (ii) neutronic requirements and related material properties, (iii) remote handling considerations, (iv) space and mass constraints and (v) the required alignment precision to allow equal distribution of the heat exposure amongst the individual of the plasma facing (PFC) limiter components. While the hot fusion plasma during ramp-up is impinging directly on the limiter, its PFC components temperature is rising and can be measured by means of either thermocouples or by infrared (IR) thermography an estimation of the heat flux on the contact point can be made. This is the basis for the proposed alignment strategy.