Design and Prototype of the High Voltage In-Service-Tests on the Superconducting Magnet System of Wendelstein 7-X
The stresses induced during the energizing and de-energizing process of the Wendelstein 7-X super conducting magnet system could cause cracks in the embedding of the winding packages and consequently a ground fault that would not be detected during normal operation as the operating voltage of the magnet is system is too low. With a ground fault present during a fast discharge, the middle point grounding needed to half the voltage could be rendered useless and one coil group could be stressed with the full voltage of up to 4 kV which would endanger the high voltage integrity of the whole superconducting magnet system. To prevent such undesirable occasions, the insulation of the superconducting magnet system shall be monitored by a high voltage In-Service-Test. With the In-Service-Test, a voltage of 2.5 kV can be applied during the operation of the magnets especially after significant changes in the coil current. The measured leak current can then be used to determine any changes in the quality of the insulation. In a first step, the feasibility of such a system has been evaluated with a simulation model of one coil group with Simplorer. The next step was to find a design which can be implemented in the given magnet power supply system and to build and test a prototype for final confirmation of the concept.
Structural analysis of W7-X: Overview
Abstract The Wendelstein 7-X (W7-X) modular stellarator is in the assembly phase at the Max-Planck-Institut fur Plasmaphysik (IPP) in Greifswald, Germany. The goal of the project is to demonstrate that this type of machine is a viable option for a fusion power-plant. The “pentagonal” magnet system of the machine encompasses 50 non-planar and 20 planar superconducting coils with sophisticated support structure. Structural reliability of components as well as resulting deformations and displacements during various modes of operation have to be considered not only for the magnet system but also throughout the whole cryostat whose main components are the plasma vessel, outer vessel, ports, and thermal insulation. A reliable prediction of the W7-X structural behaviour is only possible by employing complex finite element (FE) simulations with a hierarchical set of FE models. A special strategy has been developed and implemented for the task. The design is basically completed, main parameters are defined, and most of the W7-X components are manufactured. Therefore, the focus in the analysis is being shifted to the creation of parametric FE models which allow performing fast analyses of possible non-conformities, changes in the assembly procedure, and future exploration of operational limits. This paper gives an overview of the implemented analysis strategy, the applied safety margins, and focuses on the most remarkable results.
Factors Likely to Influence Tort Litigation in the European Union
As the European Union moves towards harmonization in a variety of business, political, and regulatory settings, an opportunity exists to influence the form of tort liability found in these nations. The opportunity should not be missed, with rising concern that U.S. influences will set into motion costly litigiousness, particularly as EU member nations pull back on the level of social programmes available to cover costs typically included in tort claims. To assist policymakers in their deliberations about European Union tort directives, this paper provides discussion of the frequently cited key differences between the U.S. tort systems and what is found in most EU member nations. The discussion is focused on available evidence regarding the influences of these differences as well as important areas of future research. The most important areas seem to be (1) the need to enforce European Law when no defined regulatory body exists for this purpose; (2) the connection between government social programmes and the need for tort liability compensation; (3) and the influence of rules governing payment of legal costs and lawyer fees.