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Wendelstein 7-X (W7-X) is a superconducting stellarator under construction at the Max-Planck-Institute for Plasma Physics in Greifswald, Germany. The magnet system consists of 70 superconducting coils providing magnetic confinement-fields. Before assembly every coil had to pass an acceptance test at the French partner-institute CEA, Saclay, to examine its performance on leak tightness, high voltage strength, ampacity, and hydraulic flow at cryogenic conditions. The testing procedure was mandatory, as access for maintenance or repair after installation will not be viable. Testing followed a well specified routine including tests in warm conditions, during cool down, in cold conditions, during warm up and at last in warm conditions. Measurement was obtained firstly by the facility's instrumentation and secondly by the coil-casing's instrumentation. The received data was transmitted to different ASCII-files for each gauge. To record testing in detail, a meta-document was edited, which follows in its structure the routine mentioned above. Accordingly, the main distinctive functions of the coil during testing are recorded in so called test reports, while deviations from given thresholds and parameters are described in non conformity reports. During testing, organizational and technical challenges had to be mastered and the test program was regularly updated to meet technical improvements, manufacturing requirements and revised assembly schedules. This paper will present the acceptance test program, its development and the gained experiences. [ABSTRACT FROM AUTHOR]

Abstract: The Wendelstein 7-X (W7-X) is an advanced optimized stellarator under construction at the Greifswald branch of the Max-Planck-Institut für Plasmaphysik. Its magnet system consists of 70 superconducting coils, i.e. five types of 10 non-planar (NPC) and two types of 10 planar (PC) individuals each. In case of an emergency shut-down like in succession of a quench, the voltage across a NPC may raise up to 450V according to the specification. Since all the 10 coils of a type are connected in series, the total voltage could thus reach 4.5kV. Therefore, the coils had to be provided with a corresponding electrical insulation. Its test voltage levels were fixed at 10.4kV and 7.2kV, respectively, for the NPCs and PCs. The coil acceptance tests take place in an ad hoc facility at CEA, Saclay where a large variety of trials are performed, including the verification of the electric insulation quality. Several DC high voltage tests (DHVT) are carried out to assess the proper manufacture of the ground insulation which stretches across the winding pack, conductor terminals, interlayer joints, and the numerous quench detection wires including their connections. The DHVTs are performed under different conditions: before cool down at room temperature and atmospheric pressure, then at cryogenic temperature and, finally, under vacuum at room temperature. Since the coils are necessarily connected to the test facility, the corresponding components like wires, plugs, or connections are also energized by the nominal voltage. Thus a flaw in the external test bed may invalidate the outcome of the experiment. It is therefore very important to determine whether the origin of a current leak is in the coil or in the test facility. To do so, it is necessary to have deep knowledge of the whole arrangement. The paper summarizes the experimental observations, data analysis, and consequent improvements which were implemented at CEA test facility. [Copyright &y& Elsevier]

Abstract: The WENDELSTEIN 7-X (W7-X) superconducting stellarator experiment i.a. consists of 50 non-planar coils (npc) and 20 planar coils (pic). Before assembly the function of every coil is tested and examined at the French partner-institute CEA, Saclay. The testing follows a certain and constant routine laid out in a master-document (Overview); the main characteristical results are then recorded in appropriate reports. This presentation will point out the importance of good documentation, give an example of how it might be organized and show its respective needs of time and manpower. After testing some of the main data is collected in various tables and analysis-software for a first assessment and statistical analysis. The results will be presented as an example of a comparative first-step-database. [Copyright &y& Elsevier]

Abstract: WENDELSTEIN 7-X (W7-X) is a superconducting stellarator which uses 50 non-planar coils for the main confinement field and 20 planar coils for the magnetic configuration. All 70 coils are subject to an extensive test program after manufacturing and before assembly, realised at the cryomagnetic test facility at CEA Saclay. The tests are part of a well-advanced quality assurance plan attesting the specified coil performance. The test program is mainly divided in warm and cold tests. Various tests have to be performed such as visual inspections, hydraulic measurements, electrical tests and the check of sensors. The most elaborate test is the cryogenic temperature margin test using current up to 17.6kA including the quench or fast discharge test and the evaluation of the specified interlayer joint resistance. Up to now 75% of the coils have been tested and accepted. The last acceptance tests at CEA are scheduled to be performed beginning of 2009. The test program has been enhanced permanently in its course, due to further improvement as well as considering aspects of the time schedule. This paper will present a short description of the test program done at CEA, their aim and background. [Copyright &y& Elsevier]