Harald Dutz

Bio: Harald Dutz is an academic researcher from Max Planck Society. The author has contributed to research in topics: Weld access hole & Heat-affected zone. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Weld integrity of the superconducting cable aluminium jackets of W7-X

Abstract: The Wendelstein 7-X (W7-X) modular stellarator is under construction at the Max-Planck-Institut fur Plasmaphysik in Greifswald, Germany. The W7-X magnet system contains 70 coils made up from helium cooled superconducting cables in aluminium alloy (EN AW-6063) jackets. Several hundred connections of the jacket to the cable joints are made by aluminium-to-aluminium welds. Due to geometrical and thermal boundary conditions these welds cannot be accomplished free from defects. Microscopic analyses of the welds show that a variety of small flaws such as cracks and pores develop during welding. The welds have thus to be dimensioned accordingly, and appropriate weld qualification, investigation and testing has to be done in order not to jeopardise the structural integrity and leak tightness. The weld is mechanically loaded during cool-down due to the difference in thermal contractions between the GRP insulation and the aluminium, and during operation by bending moments from electromagnetic forces. An extensive number of different pressure, bending, and pulling tests were performed over the years in order to verify sufficient quality of the welds. This paper is concerned with loading of the weld during cool-down in cable axis direction. It is shown that a series of simple pulling tests on the conductor jacket, welded to the cable joint, indicates that the failure starts in the heat affected zone of the jacket rather than at the weld tips where the maximal influence of welding irregularities and the notch effect is expected. In order to investigate the mechanical load distribution in the weld region, a 3D FE model was created for help in judging the criticality of weld flaws. In the course of these investigations a simple load configuration for a fast approval test of the weld was developed that can be used for the routine qualification of the welding process before real welding in W7-X takes place. Currently, acceptance criteria for the test are under development.

Experiences from design and production of Wendelstein 7-X magnets

Abstract: The Max-Planck-Institut fur Plasmaphysik in Greifswald is building the stellarator fusion experiment Wendelstein 7-X (W7-X). The manufacturing of the W7-X superconducting magnet system, which consists of 50 non-planar and 20 planar coils, was finished in March 2008. The production was a technical challenge for the W7-X design crew as well for the manufacturer due to the complex 3 D shape of the non-planar coils and the stringent requirements for geometrical tolerances. The manufacturers had to solve several technical problems and to consider major design changes even at advanced stages of manufacture. Finally the coils are passing the acceptance tests at cryogenic temperatures at CEA Saclay with a very good performance. Results of the W7-X coil production will be given and critical production steps will be identified. Lessons will be taken from the experiences gained from design, manufacturing and test methods. The reasons for the considerable time delays will be explained.

Aluminum tape connection apparatus for optical cable manufacturing

Abstract: The invention discloses an aluminum tape connection device for optical cable manufacturing. The device comprises an aluminum tape coil installation rack, a laser distance measuring sensor, a quick uncoiling device, an aluminum tape welding device, two supporting rotating wheels, a photoelectric sensor, and a controller; the aluminum tape coil installation rack comprises a first rotating shaft anda second rotating shaft; the laser distance measuring sensor is used for measuring a distance between the detection head of the laser distance measuring sensor and an aluminum tape coil mounted on thefirst rotating shaft; the quick uncoiling device is used for quickly uncoiling the aluminum tape coil mounted on the first rotating shaft, so that the aluminum tape of the aluminum tape coil can be completely uncoiled; the aluminum tape welding device is used for welding the starting end of the aluminum tape of an aluminum tape coil mounted on the second rotating shaft to the tail end of the completely uncoiled aluminum tape; the two supporting rotating wheels are arranged at intervals; the photoelectric sensor is used for sensing an aluminum tape located between the two supporting rotating wheels; and the controller is used for controlling the startup and stop of the quick uncoiling device according to the signals of the laser distance measuring sensor and the photoelectric sensor. Compared with a mode that operation and judgment are completely conducted by workers, the device can improve efficiency, and almost avoid accidents.