Energy for the future

Max Planck Institute of Plasma Physics celebrating 50-year jubilee

The object of this research is to develop a power plant that, like the sun, derives energy from fusion of atomic nuclei. One gramme of fusion fuel could provide as much energy as ten tons of coal. The raw materials needed are available in almost inexhaustible abundance throughout the world. Fusion power plants will not cause any carbon dioxide emission detrimental to the climate or any long-lived radioactive waste, and catastrophic accidents will be impossible. These are attractive properties that have motivated world-wide fusion research from the very outset.

50 years of fusion research
When Max Planck Institute for Plasma Physics was established fifty years ago, on 28 June 1960, the task was clear: to confine a hydrogen plasma by means of magnetic fields and thermally insulate it without making contact with the vessel walls, so as to heat it to an ignition temperature of over 100 million degrees. The way there, however was still an open question. A long-term programme with intensive basic research was launched in order to comprehend the highly complex and multiple feedback processes occurring in the plasma: the plasma data achieved in the first stellarator and tokamak devices were equivalent to a fusion power of just a few milliwatts. This was a long way short of the record-breaking experiment of the JET (Joint European Torus) project at Culham, UK, which attained a brief peak power of 16 megawatts twelve years ago. This constitutes a billionfold increase in fusion power. The large ITER international device, now being built at Cadarache, France, as a world-wide cooperation, is to produce the world’s first self-heating and energy-yielding plasma – an impressive development to which IPP with its experimental and theoretical work has made major contributions.

One of the outstanding milestones in fusion research was the pioneering discovery of a plasma state with good insulation that was made by IPP’s ASDEX device in 1982. In a power plant this state could triple the fusion yield. This high-confinement regime, as it is called, is meanwhile being used by all modern tokamak devices. JET achieved its record values with it, and the planning for ITER is enlisting it. IPP’s experimental tokamak research in conjunction with theory has made many contributions to the preparations for this test reactor: for example, the configuration for the magnet coils chosen for the test reactor is modelled on IPP’s ASDEX Upgrade device; the methods developed at IPP for controlling the plasma stability are to be utilised by ITER. An important research area of ASDEX Upgrade are so-called Advanced Scenarios, which allow long-pulse or even continuous operation in tokamaks, which hitherto could only be operated in pulsed mode. ASDEX Upgrade continues to develop these and other modes of operation that meet the requirements of ITER and a fusion power plant.

Equally successful has been the research on the alternative experimental line of the stellarator type: the interplay of experimental and theoretical plasma physics culminated in the development of Advanced Stellarators, which could open a simple way to a power plant capable of continuous operation. A distinctive feature of these devices are the bizarrely shaped, non-planar magnet coils, designed with sophisticated optimisation calculations. The Wendelstein 7-X experimental device, now being built at IPP’s Greifswald branch, is to achieve the favourable properties predicted by theory and demonstrate the suitability of the new stellarators for use in a power plant.

But finishing a fusion power plant still calls for major effort. An important goal is further development of the existing modes of operation to realise a magnetic confinement system that can be reliably applied in a power plant. This work will be incorporated in the planning of a demonstration power plant along with the results from ITER and from materials and technology development. If research proceeds according to plan, fusion energy could become commercially available from about the middle of the century.

Isabella Milch