Wendelstein 7-X and fusion - Max-Planck-Institut für Plasmaphysik

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Small and medium-sized enterprises
The superconducting bus bar system –
a colossal cable harness for Wendelstein 7-X
Geometry check of shaped superconductors
Facts:
Research institute:
Forschungszentrum Jülich GmbH
Industrial partner:
RASI Maschinenbau GmbH
(Illingen, Germany)
Contracts:
Development of a computer-controlled ben-
ding machine for two bending directions for
use in the construction of the superconducting
bus bar system of Wendelstein 7-X
RASI Maschinenbau GmbH, Illingen, Germany
The 70 superconducting coils of Wendelstein 7-X must be electrically and hydraulically
connected to each other as well as to the current leads. This is done by 124 three-dimensional
pre-formed superconductors. Thin filaments of the niobium-titanium superconductor
are embedded in copper wires that are twisted into a cable. Liquid helium for
cooling at the required temperature of -270 degrees Celsius flows between the individual
wires. The cable itself is enclosed in a helium-tight aluminum case. Unlike the wire
harness ín a road vehicle, for example, the shape of the connecting lines cannot be adjusted
on site, since the superconducting cable is not flexible. They thus have to be prefabricated
with a high accuracy of just a few millimeters. This made it necessary to build
and calibrate a computer-controlled bending machine. The company RASI and the Forschungszentrum
Jülich (FZJ) have jointly developed an instrument that allows bends to
be realised in two directions. Normally, a variable bending direction is made possible by
rotating the piece about its axis. Here, however, we are dealing with pre-formed parts of
several meters in length, which, during rotation would swing freely in space, even below
the floor level. The novel two-directional bending machine allows the piece always to be
turned upwards, and hence makes the whole manufacturing process possible at all.
The experience gained in developing this new machine will be valuable for future customer-specific
developments by the manufacturer. The bending machine has already
found interest from customers outside fusion research.