Construction, fabrication and performance of a compensated magnetic coil system in TEXTOR

The magnetic data base of TEXTOR tokamak comprises among others a shot to shot documentation of plasma energy, beta toroidal and global energy confinement time. The raw-data for these quantities are generated by means of a compensated magnetic coil system (diamagnetic loop). This coil system is mounted inside the vacuum vessel of TEXTOR. It is compatible with thermal cycling of the vacuum vessel and of the liner (first wall) and withstands mechanical vibrations during plasma operation. Details of construction and fabrication are briefly described. The handling of the thermal expansion problem is explained. The electrical compensation technique is shown. The performance of the compensated coil system is demonstrated using results from the measurements