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.
The power supplies for the glow discharge electrodes in Wendelstein 7-X
Abstract The conditioning of the Wendelstein 7-X (W7-X) plasma vessel will be done by glow discharges. Ten electrodes are placed inside of the vessel. Due to the three dimensional geometry the conditions for the ignition and the stabilization of a glow discharge can vary from one electrode to the other electrode. Therefore ten individual power supplies with maximum ratings of 3 kV and 3 A will be used. The ten power supplies are individually controlled by a PLC based control system. This control system is a major part of the overall glow discharge system, because it has to allow the combination of two or more power supplies to groups, which can be controlled in a similar way. The glow discharge is planned to run up to a week in steady state mode. This requires a sophisticated monitoring system of the parameters of the power supplies and the implementation of a proper matrix of reaction after failures. One aim of the Wendelstein 7-X control system is the remote control of all activities from the W7-X main control room. The glow discharge power supply control has to allow such operation and special procedures for exchange of control rights were implemented. The power supply system was developed, manufactured installed and tested in collaboration between IPP and PPT.
Secoiridoids from Olea europaea
Abstract Three new secoiridoids have been isolated from the leaves of Olea europaea along with the previously reported. The compounds were identified by spectral means.