Compass machine design and construction

COMPASS is a compact toroidal experiment currently being constructed at Culham Laboratory. The experiment is designed (1) to achieve a wide range of physics objectives for which two vacuum vessel assemblies (2) are required. The design of the magnetic field coils and structure systems (3) is complicated by the need to change the vacuum vessel during the operational life of the experiment particularly the requirement for a flush 92kA joint in the turns of the toroidal coil. The design is further complicated by the low aspect ratio (R/a = 2.4) and the number of poloidal windings necessary to achieve the many different plasma shapes. The paper describes the important aspects of the construction of the coil systems, the vacuum vessel assembly and the features of design and manufacture which influence the construction of the complete load assembly. The principles used in achieving the required accuracy of alignment is also discussed. (author). 3 refs.; 3 figs.; 1 tab