Optimisation of stellarators for fusion reactors

The reactor concept presented is based on the 5-period Helias configuration which is also the basis of the Wendelstein 7-X experiment. The magnetic field on axis is limited to 5 T, thus keeping the maximum field on the coils below 11 T. This limitation allows one to stay within NbTi-technology and to benefit from the expertise gained in the design phase of Wendelstein 7-X. Therefore the Helias reactor is an upgraded version of this experiment, with the exception that the coil system consists of one set of modular coils only. The confining field is totally generated by these coils; therefore no provisions to drive a toroidal current either by transformer coils or non-inductive means as in tokamaks have to be made. (orig.)