Divertor poloidal field

Additionally to the toroidal field coils, plasma stability and shape control requires poloidal field (PF) coils as well. Part of the PF coil set is a central solenoid, which can produce a magnetic flux increase along the axis of symmetry of the torus. The current in the toroidal field coils is essentially DC during operation, but the PF coils must be operated dynamically to counteract expansion of the plasma ring by plasma pressure and plasma current and to set the required plasma shape. Some lower current correction coils are also installed in order to compensate for small field distortions caused by tolerances in the mechanical construction. Additional coils can be placed inside the toroidal field coils for creating divertors, as described in the following section. 

Existing tokamak fusion reactor designs with magnetic divertors have therefore exclusively poloidal field or multipole divertors. But using versions with multipoles installed inside, as in ASDEX, it has not yet been possible to find a feasible solution compatible with reactor access, manufacture and service requirements. 

Poloidal field divertors with external multipoles would appreciably simplify access and manufacture, but greatly increase operating and manufacturing costs. We shall return to this point later. Poloidal field divertors will also have a problem with the load capacity of the collectors. 

Poloidal field system with magnetic divertor... 

The technical problems of the poloidal field system depend on the configuration concept of the equilibrium field coils and the multipole divertor winding. A basic distinction is made between two types of configuration ... 

Resume POLOIDAL FIELD SYSTEM FOR COMMERCIAL FUSION REACTORS WITH MULTIPOLE DIVERTOR COILS ARE NOT YET FEASIBLE. 

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