No abstract

Abstract-The magnet system of the Wendelstein 7-X stellarator (W7-X) consists of 50 non-planar and 20 planar coils. In particular, the winding packs of the non-planar coils are densely packed and compressed in the area of inter-layer joints and coil terminations, which brings some risk of inter-turn and inter-layer short circuits.The paper describes methods deducted from impulse and ac tests performed on the coils, which enable demonstrating the absence of short circuits and weak points of low inter-layer insulation resistance. In the impulse test, frequency and damping are compared for coils with and without short circuits and coils with an external low resistance bypass. With ac voltage, a drastically reduced impedance clearly indicates a short circuit. Therefore both tests represent excellent QA (quality assurance) tools for checking the uniformity of the electromagnetic performance of a serial production of magnet coils.

No abstract

A bath cooled superconducting solenoid with a 280 mm in diameter warm bore, a coil length of 1200 mm and a central field of 5 T at the rated current of 950 A, was built at Ansaldo ABB Componenti. It will operate as compensating coil inside the Zeus Detector at HERA, Desy. The coil is shielded by a 3.5 tons low carbon steel cold yoke and the cold helium chamber was designed to withstand a max pressure of 20 bar. The main results obtained during the cool down and energization are reported.

No abstract