Plasma assessments for the fusion engineering device (FED)

An initial range of plasma assumptions and scenarios has been examined for the U.S. tokamak FED concept. The results suggest that the current FED baseline parameters of R=4.8 m, Bsub(t)=3.6 T, a=1.3 m, b=2.1 m (D-shape), and Isub(p)=4.8-5.4 MA are appropriate for achieving its nominal goals of P(fusion) approximately equal to 180 MW and a plasma Q approximately >5 for a pulse length greater than 100 s. However, large uncertainty still exists in the areas of current startup, ion-cyclotron wave launching, influence of plasma shape on achievable beta, impurity control, plasma edge transport, and plasma disruption. Various options and remedies have been suggested to alleviate the impact of the uncertainty on the FED design concept. They appear promising because they can be studied experimentally and are not expected to lead to fundamental design modifications of FED. (author)