6
LARGE
CORPORATIONS
MAN Energy Solutions SE,
Deggendorf, Germany
“The Mona Lisa of the art of welding” *
The plasma vessel of the Wendelstein 7-X
The plasma vessel for the Wendelstein 7-X fusion
experiment, which looks like a wound-up steel tube,
is designed to accommodate a hydrogen plasma with
a temperature of about 100 million degrees. The almost
ring-shaped plasma chamber has an outer diameter of 12.8
meters and a height of 2.5 meters. The steel vessel must match
precisely the symmetry of the magnetic field which confines
the hot plasma. The requirements placed on the steel vessel
construction thus presented completely new challenges for
MAN Energy Solutions: it was necessary to manufacture an
unusually complex, three-dimensional vessel with a volume of
30 cubic meters made of 17 millimeters thick stainless steel –
with a dimensional tolerance of two millimeters (plus/minus)!
Altogether, the plasma chamber consists of 200 stainless steel
rings. Each ring is composed of 15 centimeter-wide steel
strips, which are bent in several places in order to achieve the
required contoured geometry. 20 sectors were fabricated from
these rings and delivered to Greifswald were they were welded
together onsite using techniques suitable for ultra-high vacuum,
resulting in the completed chamber. The plasma vessel wall has
roughly 300 ports of different sizes, which are necessary for
heating the plasma and investigating it scientifically.
To successfully complete the project, MAN had to introduce a
variety of new technologies at its Deggendorf site:
▶ Before manufacturing such a complex vessel, detailed
computer models had to be developed. This prompted MAN
Energy Solutions to introduce the most advanced program
available for three-dimensional spatial design. Since then,
3D-spatial design has become part of the company‘s expertise.
▶ The dimensional accuracy of the vessel had to comply with
the highest standards. For checking and verifying the geometry
of the vessel MAN Energy Solutions in Deggendorf applied an
electronic, laser-assisted surveying system for the first time,
which is now routinely used in all production at the company.
Welding the Wendelstein 7-X plasma vessel
*Der Spiegel 1/2009 (a German news magazine)
Photo: IPP, Wolfgang Filser