Poland’s fusion programme concentrating on Wendelstein 7 X
Millions invested in German device / specialists from Poland working on Wendelstein 7 X
The aim of fusion research is to develop a power plant that, like the sun, derives energy from fusion of atomic nuclei. To do this, the fuel – an ionized low-density gas, a plasma – has to be confined with almost no contact in a magnetic field cage and then heated to ignition temperatures exceeding 100 million degrees. Once completed, the Wendelstein 7 X fusion device, now being built at Max Planck Institute for Plasma Physics in Greifswald, will be the world’s largest and most modern device of the stellarator type. Its magnetic field makes continuous operation possible in a simple way.
The magnetic cage is generated by a wreath of 50 bizarrely-shaped magnet coils, these being the technical core of the device. When these are cooled to the superconducting temperature, close to absolute zero, the current later flowing through them will suffer almost no loss. They are wound from a finger-thick cable whose aluminium sheath encloses a flex of thin copper wires in which the superconducting niobium titanium strands – the actual conductors – are embedded. Supercold liquid helium as coolant will later flow in the space between the individual wires and the sheath.
Superconductivity specialists at the Institute of Nuclear Physics of the Polish Academy of Sciences at Cracow took on the tricky job of interconnecting the coils. Jülich Research Centre provided the necessary connecting pieces – rigid, up to 14 metres long superconductors, delivered already in their final form. Once unpacked, the unwieldy conductors presented some challenge in getting them transported into the assembly hall. Finally, helium-filled balloons were enlisted to levitate the sensitive components carefully into the hall. Up to 45 technicians and engineers from Cracow were occupied at Greifswald for six years in interconnecting the coils with a total of 121 conductors by means of 240 joints and 400 support elements, likewise produced at Jülich.
After more than 160 man-years of work the last coil connection is linked, insulated against high voltage and checked for helium tightness. “We are most grateful for this excellent achievement and look forward to further cooperation”, stated Project Head Prof. Dr. Thomas Klinger on completion of this complicated mounting procedure. Now that the Cracow specialists have departed from Greifswald, cooperation is being continued with the National Centre for Nuclear Research at Swierk in Poland: The accelerator specialists are occupied with production of components for the neutral-particle heating in Wendelstein 7-X. This will heat the plasma by injecting fast particles into it. The production orders have already been placed with Polish and other European industrial concerns.
Two-thirds of the cost of the two projects is being met by the Polish Ministry of Science, who want to develop their fusion research programme around Wendelstein 7-X. In addition, IPP-financed cooperation projects for plasma diagnostics with the Universities of Warsaw and Opole are planned. “With their contributions of personnel from Cracow and Swierk the Polish Science Ministry are providing a total of 6.5 million euros for Wendelstein 7-X”, states Prof. Klinger. “This makes Poland, after the USA*, the second largest contributor to Wendelstein 7-X.”
* see IPP Press Release 8/11