The in-vessel components of the experiment WENDELSTEIN 7-X

The stellarator device Wendelstein 7-X (W7-X) is now in the final stage of assembly. All the machine components have been built and in mid 2014 the commissioning activities should start. The first objective of W7-X is to prove the stellarator optimization principles, i.e., to reach at least the same confinement quality as a similar sized tokamak. The second objective is to demonstrate stable high-power steady-state operation. In the present paper, after a short description of the device, the ongoing activities to complete the construction will be summarized, focusing on the optimization of the layout of the torus hall and on the completion and assembly of the in-vessel components. The main lessons learned during the assembly will be presented as well as the application of the quality control, the handling of non-conformities and the design change procedures. The planning of the commissioning sequences to perform the integral tests of the major W7-X systems is discussed in order to prepare the W7-X device to start plasma operation.

Section: The W7-x Machinementioning

confidence: 99%

Wendelstein 7-X—Status of the project and commissioning planning

Gasparotto

Baylard

Bosch

et al. 2014

“…Different types of plasma facing components (PFCs) have to be cooled: divertor target modules, baffle modules, heat shields and panels of the first wall protection. The detailed description of these components can be found in [3]. The major differences between these components are the cooling conditions such as the velocity and the operating pressure as a consequence of the different loadings: 10 m/s and 2.8 MPa for the targets, 6 m/s and 2.5 MPa for the baffles and heat shields, 2 m/s and 2.5 MPa for the panels.…”

Section: Layoutmentioning

confidence: 99%

Design analysis and manufacturing of the cooling lines of the in vessel components of WENDELSTEIN 7-X

Mendelevitch

Vorköper

Boscary

et al. 2011

Self Cite

All In-Vessel Components (IVCs) of W7-X are actively cooled. Inside the plasma vessel about 4 km of pipes will be installed, supplying water to the IVC. 226 cooling circuits with 78 variants are necessary. The cooling circuits enter the cryostat and the plasma vessel through ad hoc flanged penetrations called "plugins", which provide for the vacuum boundary between the plasma chamber and the torus hall atmosphere. The plug-ins are installed inside the W7-X ports. Some of the plug-ins are also used for the diagnostic cables. In total eighty plug-ins will be produced and installed. The inlet / outlet cooling lines are connected to the plug-ins using a welded hydraulic connector. The lay-out of the cooling lines is rather complex in consideration of the limited space and the routing between many component parts. Additionally the differential thermal expansion of the lines with respect to the supporting structures during the different operation scenarios had to be compensated by ad-hoc supports and adjustments in the flexibility of the lines.

“…For long pulse operation of the Wendelstein 7-X (W7-X) stellarator it is foreseen to install an actively water cooled high heat flux (HHF) divertor, consisting of individual target modules [1]. Each module is a set of target elements made of CFC tiles bonded to a CuCrZr heat sink, which are mounted onto a support frame.…”

Section: Introductionmentioning

confidence: 99%

Mechanical analysis of the joint between Wendelstein 7-X target elements and the divertor frame structure

Smirnow

Kuchelmeister

Boscary

et al. 2014

Self Cite

The target elements of the actively cooled high heat flux (HHF) divertor of Wendelstein 7-X are made of CFC (carbon fibre-reinforced carbon composite) tiles bonded to a CuCrZr heat sink and are mounted onto a support frame. During operation, the power loading will result in the thermal expansion of the target elements. Their attachment to the support frame needs to provide, on the one hand, enough flexibility to allow some movement to release the induced thermal stresses and, on the other hand, to provide enough stiffness to avoid a misalignment of one target element relative to the others. This flexibility is realized by a spring element made of a stack of disc springs together with a sliding support at one of the two or three mounting points. Detailed finite element calculations have shown that the deformation of the heat sink leads to some non-axial deformation of the spring elements. A mechanical test was performed to validate the attachment design under cyclic loading and to measure the deformations typical of the expected deformation of the elements. The outcome of this study is the validation of the design selected for the attachment of the target elements, which survived experimentally the applied mechanical cycling which simulates the thermal cycling under operation.