Mechanical experiments about pendulum support of vacuum vessel W7-X
Introduction
At the Max-Planck-Institut für Plasmaphysik (IPP) in Greifswald, the new stellarator Wendelstein 7-X (W7-X) is under construction. Its toroidal plasma (major diameter of 11 m) is directly enclosed by the vacuum vessel (VV). The vertical VV support system has to fulfil three functions:
- 1.
Withstand all the vertical loads
- 2.
Vertical adjustment (by hydraulic cylinders)
- 3.
Allow (passive) horizontal movement
Fig. 1 shows a schematic cut through the cryostat where are shown the main components (especially one inner vertical support) and the movements.
Section snippets
Values and design of the vertical support system
The VV of W7-X consists of five uniform modules (5× 72°). Each of them has to be supported and adjusted separately.
Therefore each VV module will be supported by three vertical supports which are of different lengths because of geometrical environment [1]. Two supports are located on the inner side and the third is placed at the outer side of the VV (Fig. 2).
The total number of VVS is accordingly 15.
The accepted total vertical load (dead weight) plus safety margin is 1300 kN. Conservatively
Experimental objectives
The goal was to find a convenient material and geometry of the hemisphere (ball/cup).
Therefore, analyses and tests had to be performed.
In order to prove that this pendulum support system has a low frictional resistance a series of experiments was developed, which were carried out at the University of Rostock.
At first the influence of the length of the pendulum support was examined. Secondly the required horizontal forces and respectively the equivalent friction factor were found.
The friction
Conclusions
The general feasibility of the pendulum support could be proved with the experiments. Different materials and geometries were tested.
The latest test (19) with cup material 1.4429 and ball material CC496K (lead–bronze) achieved the best results.
Therefore, this will be used for original VVS.
The observed smaller horizontal forces triggered by them will be used for following calculations of the whole cryostat.
References (4)
- B. Missal, T.S. Test Pendelstütze für vertikale PG-Abstützung, IPP document Nr. 1-ABH00V-S0005.1, 22.12.2005, Max...
- B. Missal, Zwischen-Auswertung der 1:1 Tests von Pendelstützen (Uni Rostock), IPP document Nr. 1-ABH00V-T0019.0,...
Cited by (3)
Preliminary structural assessment of the HELIAS 5-B breeding blanket
2019, Fusion Engineering and DesignCitation Excerpt :In particular, assuming the same material percentages as the HCPB and WCLL DEMO BB [18], the ρeq values have been calculated at the aforesaid average temperatures (Table 1). In order to simulate the continuity of the VV, a symmetry boundary condition along the direction normal to each VV side faces (local toroidal directions) has been imposed to nodes highlighted in red in Fig. 3 B and C. Moreover, in order to reproduce the effect of the pendulum supports typically envisaged for a stellarator machine [19], displacement along the global Z direction has been prevented to nodes highlighted in red in Fig. 3 A. Lastly, purely for numerical reasons, one node on the VV top and one on the bottom have been constrained along the global X direction. Furthermore an equivalent Young´s Modulus equal to the 10% of the actual one, for Eurofer and AISI 316, has been assumed in dummy components in order to ensure that their displacement is comparable with that of the real structure [20].
Pendulum support of the W7-X plasma vessel: Design, tests, manufacturing, assembly, critical aspects, status
2014, Fusion Engineering and DesignCitation Excerpt :Because of these very positive results it was decided to finish the tests and use this material combination (cup material 1.4429 and ball material CC496K) for all plasma vessel supports in W7-X. A detailed description of the test results can be found in Refs. [1,3]. After the successful verification of the working principle and clarification of material the fabrication was released.
Estimation of chaotic thresholds for the recently proposed rotating pendulum
2013, International Journal of Bifurcation and Chaos