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The WENDELSTEIN 7-X, a superconducting fusion experiment, is under construction at the Griefswald branch of the Max-Planck-Institut fur Plasmaphysik (IPP). The accuracy of the coil system is determined by the accuracy of the shape of the winding packs, the accuracy of the final machining of the casings and the accuracy of the assembly of the stellator.

A protection system capable of rapidly reducing current in coils is needed for WENDELSTEIN 7-X (W7-X), a superconducting fusion experiment under construction at the Greifswald facility of the Max Planck Institut fur Plasmaphysik (IPP), in Germany. The solution that has been selected is described.

There are three main magnet systems in Wendelstein 7-X (W7-X), comprising in total 85 coils arranged in 22 independent circuits fed by steady-state power supplies. The superconducting coil system creates the main magnetic field and consists of 70 coils, grouped in 7 electrical circuits with 10 coils each with an inductance of $\sim 1$ H. Each circuit is fed by one power supply with a maximum current of 20 kA and a maximum voltage of ±30 V. The second coil system is the so-called trim coil system, intended for enhanced experimental flexibility and error field corrections. It consists of five independently powered copper coils that are placed on the outer side of the cryostat. They will be operated with the currents of up to 1.95 kA. The full-scale ratings of a power supply are ±2200 A(dc) and ±230 V(dc). The third magnet system is the divertor control coil system. The ten normal conducting copper coils are situated inside the plasma vessel behind the divertor targets and are arranged in ten independent circuits. The current rating of one power supply is a dc current of up to ±2500 A, which can be modulated by an ac current of up to 625 A with the frequencies of up to 20 Hz. The commissioning of all the systems was made first by using dummy loads, and finally with the installed coils in W7-X. The final commissioning has been running since November 2014 and will be completed in Summer 2015. [ABSTRACT FROM AUTHOR]

The magnet system of the fusion experiment Wendelstein 7-X (W7-X) consists of superconducting as well as normal conducting coils. 50 non planar superconducting coils are forming the main field, 20 planar superconducting coils allow varying the shape of the plasma. Inside of the plasma vessel 10 normal conducting control coils will be placed to modify the strike points of the plasma at the divertor. In addition a set of five normal conducting trim coils has been designed to allow the correction of error fields and to increase the experimental flexibility. The coils will be placed at the outer surface of the outer vessel of W7-X. Four out of five coils have identical size and shape. They have dimensions of 3.5 \times 3.3 meters with 48 turns and will be operated with currents of up to 1.8 kA. The other coil type has a smaller size of 2.8 \times 2.2 meters, but a higher number of turns and a higher operating current of 1.95 kA. Both types of trim coils will be made of square copper hollow profile with an integrated cooling channel. Five independent power supplies will be used to energize the coils. The present concept is based on four-quadrant power supplies. The control system will allow the local control as well as the remote control of the five power supplies from an external control room. [ABSTRACT FROM PUBLISHER]

The superconducting magnet system of the WENDELSTEIN 7-X (W7-X) experiment consists of 50 non-planar and 20 planar coils which are connected in series in seven groups of ten coils each. In order to be able to vary the magnetic configuration the five groups of non-planar coils and two groups of planar coils will be powered individually resulting in seven independent power supplies. It is necessary to equip each of the seven power supplies for the superconducting coils with a protection system to avoid overheating of the coils in case of a quench. The paper describes the design of the power supplies and the protection system for W7-X and gives a detailed description of the acceptance tests of the first module of the power supply and protection system. [ABSTRACT FROM AUTHOR]

Botulinum neurotoxin serotype C (BoNT/C) is a neuroparalytic toxin associated with outbreaks of animal botulism, particularly in birds, and is the only BoNT known to cleave two different SNARE proteins, SNAP-25 and syntaxin. BoNT/C was shown to be a good substitute for BoNT/A1 in human dystonia therapy because of its long lasting effects and absence of neuromuscular damage. Two triple mutants of BoNT/C, namely BoNT/C S51T/R52N/N53P (BoNT/C α-51) and BoNT/C L200W/M221W/I226W (BoNT/C α-3W), were recently reported to selectively cleave syntaxin and have been used here to evaluate the individual contribution of SNAP-25 and syntaxin cleavage to the effect of BoNT/C in vivo. Although BoNT/C α-51 and BoNT/C α-3W toxins cleave syntaxin with similar efficiency, we unexpectedly found also cleavage of SNAP-25, although to a lesser extent than wild type BoNT/C. Interestingly, the BoNT/C mutants exhibit reduced lethality compared to wild type toxin, a result that correlated with their residual activity against SNAP-25. In spite of this, a local injection of BoNT/C α-51 persistently impairs neuromuscular junction activity. This is due to an initial phase in which SNAP-25 cleavage causes a complete blockade of neurotransmission, and to a second phase of incomplete impairment ascribable to syntaxin cleavage. Together, these results indicate that neuroparalysis of BoNT/C at the neuromuscular junction is due to SNAP-25 cleavage, while the proteolysis of syntaxin provides a substantial, but incomplete, neuromuscular impairment. In light of this evidence, we discuss a possible clinical use of BoNT/C α-51 as a botulinum neurotoxin endowed with a wide safety margin and a long lasting effect. [ABSTRACT FROM AUTHOR]