Test of the EURATOM LCT coil (NbTi conductor) with forced flow HeII cooling

The EURATOM LCT coil, a D shaped NbTi coil, was tested in the TOSKA facilit y at Forschungszentrum Karlsruhe with pressurized forced flow He II cooling . A suitable cryogenic system based on an existing 1.8 K He II 300 W liquif ier was designed for cooling the coil by pressurized forced flow He II circ ulated by pumps across heat exchangers immersed in a He II bath. Three type s of pumps (piston, centrifugal, thermomechanical) were used. The cryogenic system worked well under usual operation and fault conditions. No signific ant differences were found between He I and He II forced flow cooling. The D-shaped coil was reinforced by stainless steel belts keeping the D shape i n single coil operation mode. No backlash was found between the coil and it s reinforcement structure in agreement with predictions of the finite eleme nt analysis. The coil achieved similar to 11 T as predicted from single str and measurements and previous tests in the frame of the Large Coil Programm e. The results are an encouraging step in using this technology in large su perconducting magnet systems for magnetic confinement in fusion research. ( C) 1999 Elsevier Science S.A. All rights reserved.