Design of simple stellarator using tilted toroidal field coils

Abstract

This paper deals with the design of the stellarator field with the simple coil set. In order to realize the stellarator field by the simple coil set, tilted toroidal field coils are used for creating the rotational transform. Sixteen tilted TF coils create the small radial field and large vertical field. If the axisymmetric poloidal field coil can compensate for the larger vertical field of tilted TF coils, the stellarator field can be realized. The formation of clear and nested flux surfaces is confirmed, and the rotational transform is proportional to the tilting angle of the toroidal field coil. The main features of the magnetic field for the simple stellarator in this paper are the large mirror ripple and small helical ripple. This is a similar property to the quasi-isodynamic configuration like the Wendelstein 7-X stellarator. The collisionless orbit for the proton is studied. For a moderate tilting angle of the toroidal field coil, the confinement of the passing and trapped particles improves.