Innovation in Design and fabrication of Compact Stellarators

The Quasi-Poloidal Stellarator (QPS) is being developed to test key physics issues at very low plasma aspect ratio, 1/2-1/4 that of existing stellarators. Engineering innovation is driven by both the complex 3-D design requirements and the need for reduced cost and risk in fabrication. Complex, highly accurate stainless steel modular coil winding forms are cast and machined; conductor is wound directly onto the modular coil winding forms; a vacuum-tight cover is welded over each coil pack; the coils are vacuum pressure impregnated; and the completed coils are installed in an external vacuum vessel. As a result, QPS differs significantly in design and construction from other toroidal devices. Figure 1 shows a cutaway view of the QPS device.