F. Rau

Magnetic Field, Force and Stress Calculations for Modular Helias Coil Systems

At IPP Garching, the future experiment WENDELSTEIN VII-X is being developed. A Helias configuration ( Helical A dvanced S tellarator) has been chosen because of its confinement and stability properties. Superconducting coils are favoured because of their steady state field, but pulsed water-cooled copper coils could be used also. Two limiting cases are studied for WVII-X with the major radius between R 0 = 5 m and R 0 = 6.5 m, the magnetic induction between B 0 = 4 T and B 0 = 3 T at a stored magnetic energy of W ≈ 0.66 GJ and W ≈ 0.88 GJ. The stress and strain distributions caused by the electromagnetic forces have been investigated by finite-element computations. A mutual support scheme is used between adjacent coils. For a typical load case, the equivalent stress reaches a peak value of about 110 MPa in the composite conductor.

MECHANICAL BEHAVIOUR OF MEDIUM SIZED MODULAR STELLARATOR COIL CONFIGURATIONS

A coil system, called WVII-X-1D, of an Advanced Stellarator with modular non-planar coils is described. It is similar to that of the WENDELSTEIN VII-AS and is considered as one option for the next-generation experiment WVII-X. The coils for WVII-X-1D with R o = 5 m , r c = 1.2 m are considered as superconducting, and produce an induction of B o = 4 T at a stored magnetic energy W ≈ 1 GJ . The stress and strain distributions caused by the electromagnetic forces are investigated by finite-element computations, a mutual support scheme being used between adjacent coils. For a typical load case, the equivalent stress reaches a peak value of about 75 Mpa at a maximum strain of 0.1 % in the composite conductor.

Vacuum Magnetic Field and Modular Coil System of the Advanced Stellarator Wendelstein VII-AS

The vacuum field and the modular coils of the Advanced Stellarator WENDELSTEIN VII-AS are described. Each of the five field periods contains 9 different twisted coils, one of them with increased dimensions and current to provide sufficient access for neutral beam injection. The standard configuration (8 = 3 T, rotational transform τ= 0.39, aspect ratio ξ 10, low shear, and magnetic well) can be varied by toroidal and vertical fields, or by changing independently the current in the special coils. From a study of magnetic field perturbations some estimates are derived for the admissible coil tolerances.