The present disclosure is directed to stellarators or assemblies including a stellarator including removable and/or replaceable components, such as removable field shaping units and/or removable shaping coils. In some embodiments, the stellarators of the present disclosure include a toroidal sector, which includes one or more removable field shaping units.

Disclosed herein is a stellarator comprising two sets of coils, namely a set of encircling coils which encircle the plasma axis, and a set of shaping coils which do not encircle any other coil or the plasma. In some embodiments, the encircling coils include a structural element to maintain their shape under magnetic forces. In some embodiments, the shaping coils are mounted onto one or more structural elements which, together with the shaping coils, constitute a field shaping unit. Also disclosed is a controller which may modify the electrical current flowing in one or more subsets of the coils in order to achieve target plasma parameters. Also disclosed is a method of designing a set of shaping coils by discretizing a surface dipole or current potential distribution.

The present disclosure is directed to systems for generating neutrons, the systems including a stellarator optimized for fast particle finement. In some embodiments, the stellarator optimized for fast particle confinement is selected from a quasi-axisymmetric stellarator, a quasi-symmetric stellarator, a quasi-isodynamic stellarator, or a quasi-omnigenous stellarator. The present disclosure is also directed to methods of generating neutrons using the systems of the present disclosure and, in particular, systems incorporating a stellarator optimized for fast particle confinement.

The present disclosure is directed to a method of generating a set of torsion-restricted free parameters which describe a design of one or more electromagnetic coils, such as for use in a stellarator. In some embodiments, the computing of the set of torsion-restricted free parameters describing the one or more substantially planar coils includes a parametrization which describes one or more non-planar coils.

Disclosed herein is a stellarator comprising two sets of coils, namely a set of encircling coils which encircle the plasma axis, and a set of shaping coils which do not encircle any other coil or the plasma. In some embodiments, the encircling coils include a structural element to maintain their shape under magnetic forces. In some embodiments, the shaping coils are mounted onto one or more structural elements which, together with the shaping coils, constitute a field shaping unit. Also disclosed is a controller which may modify the electrical current flowing in one or more subsets of the coils in order to achieve target plasma parameters. Also disclosed is a method of designing a set of shaping coils by discretizing a surface dipole or current potential distribution.