European Prize for IPP Plasma Physicists
Hannes Alfvén Prize awarded to Jürgen Nührenberg and Alan Boozer
The two scientists are being honoured for their outstanding contributions to improving the stellarator principle. The Wendelstein 7-X fusion device, now being built at IPP’s Greifswald branch, is a configuration of this type. The fact that with Wendelstein 7-X a large-scale device of the stellarator type is now capable of entering into competition with the devices of the tokamak type, preferred world-wide, is essentially owed to the two theoreticians.
IPP’s research objective is to develop a power plant that, like the sun, derives energy from fusion of atomic nuclei. For this purpose the scientists have to succeed in confining the fuel – an ionised low-density hydrogen gas, called plasma – in a ring-shaped magnetic field cage and heating it to ignition temperatures of over 100 million degrees.
Whereas the magnetic field of tokamaks has a simple circularly-symmetric shape, the complexly structured stellarators lack this symmetry. This affords the advantage that stellarators, unlike the pulsating tokamaks, can operate in continuous mode. The disadvantage is that classical stellarators do not confine the plasma as well as tokamaks do. The optimisation of stellarators to eliminate this shortcoming was made possible by two pioneering discoveries: Alan Boozer’s formulation of the conditions under which stellarator fields also achieve good confinement, and Jürgen Nührenberg’s proving that, and how, such “quasi-symmetric” systems can be achieved in concrete magnetic field configurations. The latter was also able to show that there are other configurations with good confinement properties. It was on this theory in conjunction with the many years of experimental and engineering experience in stellarator research at IPP that the plans for Wendelstein 7-X took shape.
The prize, named after Swedish plasma physicist Hannes Alfvén, is awarded annually by the Plasma Physics Section of the European Physical Society for outstanding achievements in the field of plasma physics.