Asymmetry of W7-X magnet system introduced by torus assembly

Fellinger, J.; Egorov, K.; Kallmeyer, J. P.; Bykov, V.; Schauer, F.

doi:10.1016/j.fusengdes.2014.01.081

Cited by 5 publications

(6 citation statements)

References 3 publications

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“…Several other sources of possible magnet system asymmetries were simulated with help of finite element (FE) models. Two 360° FE global models of the Wendelstein 7-X magnet system were created with the ANSYS and ABAQUS codes [10,11,12]. By means of these Models deformations of all 70 superconducting coils under the dead-weight, cool-down and electromagnetic loads in different operation regimes were simulated.…”

Section: A Tolerances Of the Magnetic Fieldmentioning

confidence: 99%

Engineering Challenges in W7-X: Lessons Learned and Status for the Second Operation Phase

Bosch

Andreeva

Brakel

et al. 2018

IEEE Trans. Plasma Sci.

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In 2015 the optimized stellarator Wendelstein 7-X stellarator (W7-X) started with operation. The main objective of W7-X is the demonstration of the integrated reactor potential of the optimized stellarator line. An important element of this mission is the achievement of high heating-power and high confinement in steady-state operation. The approach to this mission is following three steps. First plasmas were produced in a limiter configuration (OP 1.1), then a test divertor unit is being installed (TDU) for the next campaign, OP 1.2, before the full steady state capability will be achieved implementing active cooling of all in-vessel components and a steady state high heat flux divertor. In December 2015, the first helium plasma was generated using Electron Cyclotron Resonance Heating (ECRH), in February 2016 the working gas was switched to hydrogen. The first operation phase (OP 1.1) was successfully finished in March 2016. At the end of OP 1.1 the discharge duration was close to 6 seconds, the limit for the integrated heating power was increased to 4 MJ and electron temperatures of ~10 keV were achieved. Due to the low densities in the range of 10 19 cm-3 and the pure electron heating by ECRH, the ion temperatures reached only 2 keV. At present, W7-X is undergoing the next completion phase, including the installation of the test divertor unit, the installation of the carbon tiles on the inner plasma vessel wall, an upgrade of existing diagnostics and the installation of new diagnostics. This paper discusses the first operational phase, lessons learned and implemented and the status before the start of the second operational phase (OP 1.2).

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Section: A Tolerances Of the Magnetic Fieldmentioning

confidence: 99%

Engineering Challenges in W7-X: Lessons Learned and Status for the Second Operation Phase

Bosch

Andreeva

Brakel

et al. 2018

IEEE Trans. Plasma Sci.

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“…In contrast to manufacturing and positioning errors, these asymmetries could only be indirectly checked and therefore had to be simulated with finite element (FE) methods to estimate corresponding deformations of the coils, necessary for the evaluation of the magnetic field perturbation. For this purpose, two FE models of Wendelstein 7-X were used, created with the ANSYS and ABAQUS codes, respectively [8][9][10]. These models differ in the modelling of sliding contacts and meshing.…”

Section: Finite Element Calculations Of Deformations Of Wendelstein 7...mentioning

confidence: 99%

“…This was, however, not the case due to the sequential loading of the machine base, the connection of adjacent modules to each other and the removal of temporary supports (see figure 4). The influence of these steps was simulated with the 360 • ABAQUS FE Model, which encompasses the complete torus including the machine base [9]. Two simulations were made, both using ideal modules, sequentially placed in their CAD positions.…”

Section: Torus Assembly After Module Positioningmentioning

confidence: 99%

Tracking of the magnet system geometry during Wendelstein 7-X construction to achieve the designed magnetic field

et al. 2015

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Wendelstein 7-X, currently under commissioning at the Max-Planck-Institut für Plasmaphysik in Greifswald, Germany, is a modular advanced stellarator, combining the modular coil concept with optimized properties of the plasma. Most of the envisaged magnetic configurations of the machine are rather sensitive to symmetry breaking perturbations which are the consequence of unavoidable manufacturing and assembly tolerances. This overview describes the successive tracking of the Wendelstein 7-X magnet system geometry starting from the manufacturing of the winding packs up to the modelling of the influence of operation loads. The deviations found were used to calculate the resulting error fields and to compare them with the compensation capacity of the trim coils.

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“…The two independent 360 • FE models in ANSYS and ABAQUS [5] were used due to the criticality of the cryo-leg issues [6] to benchmark results and conclusions. The ABAQUS 360 • model (see figure 2(b)), originally dedicated to the analysis of assembly steps [7], has been recently extended into a full operational model. Due to highly time consuming calculations it was decided to fix, by bonding, some contacts inside the models which were considered as not important for the tasks.…”

Section: Fe Analysis Of Additional Loads On the Cryo-legs And Tie-rodsmentioning

confidence: 99%

Sliding weight supports for W7-X magnet system: structural aspects

Bykov¹,

Fellinger²,

Egorov³

et al. 2015

Nucl. Fusion

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The Wendelstein 7-X (W7-X) stellarator is presently under commissioning at the Max-Planck-Institut für Plasmaphysik in Greifswald. The coil system consisting of 70 superconducting coils of seven different types is supported by a massive central support structure (CSS), and thermally protected by the cryostat. The magnet system weight is borne by supports which are bolted to the cold CSS. These ten so-called cryo-legs penetrate through the cryostat wall to the warm machine base. The design of the cryo-legs incorporates glass-reinforced plastic tubes to guarantee relatively small thermal conductivity. In order to ensure free thermal shrinkage of the magnet system and to reduce stresses in the cryo-legs, sliding and rotating bearings are used as interfaces to the machine base. Tie-rods between the machine base and the warm ends of the cryo-legs prevent toroidal rotation of the magnet system, as well as any other horizontal shifts due to asymmetric loads. The assembly of the magnet system introduced some vertical imperfections in the cryo-leg positions causing considerable additional internal stresses which were not considered during the design stage. In addition, originally not planned trim coils induce unsymmetrical cyclic loads. Therefore, the previously used method to analyse one magnet system module with periodical boundary conditions is not applicable. Consequently, a model of the complete magnet system, including all five modules, was created and analysed. Fatigue analyses of the cryo-legs under the new cyclic loads, applied on top of the approximately 100 t static weight, have been performed in order to evaluate the lifetime. The paper presents the progress in structural analyses of the W7-X magnet system under the as-built conditions, loads due to the trim coil operation, and results of the weight support fatigue analysis.

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Asymmetry of W7-X magnet system introduced by torus assembly

Cited by 5 publications

References 3 publications

Engineering Challenges in W7-X: Lessons Learned and Status for the Second Operation Phase

Engineering Challenges in W7-X: Lessons Learned and Status for the Second Operation Phase

Tracking of the magnet system geometry during Wendelstein 7-X construction to achieve the designed magnetic field

Sliding weight supports for W7-X magnet system: structural aspects

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