Provisions for out-of-plane support of the TF coils in recent tokamaks

Out-of-plane (OOP) loads on a Toroidal Field (TF) coil, caused the interaction of the poloidal field and toroidal field coil current, have been a challenge in recent tokamaks, such as C-MOD, ITER, IGNITOR, and FIRE. These loads have been an important structural problem, often driving the structural design of the magnet system as much as the large in-plane loads. Each of the tokamak designs discussed has unique problems in supporting the OOP loads. Stresses due to in-plane loads may be readily predicted from simple relations, and these are typically used in systems codes to size reactors. Support of OOP loads is typically statically in-determinant, and requires larger scale structural simulation. In recent tokamaks, with highly shaped plasmas, major design challenges resulted when the OOP load carrying features were added. OOP support issues relating to these reactors are discussed in greater detail in this paper. A simplified method for calculating OOP shear stresses and their distributions, suitable for system codes, is presented.