Stern-Gerlach Medal 2009 for Friedrich Wagner

IPP plasma physicist honoured by the German Physical Society

The objective of fusion research is to develop a power plant which, like the sun, derives energy from fusion of atomic nuclei. To ignite fusion reactions one has to succeed in confining the fuel – an ionised low-density hydrogen gas, called plasma – in a magnetic field cage and heat it to a high temperature. Not an easy goal, as history shows: When, for example, at the end of the 1970s powerful methods of heating the plasma had been developed, this at first did not bring the success anticipated, but presented instead a grave problem observed world-wide. The most important property of magnetic confinement, viz. thermal insulation of the plasma, deteriorated as soon as the plasma temperature was increased by external heating. The thermal insulation inevitably diminished as the temperature approached the ignition condition. Under these circumstances it seemed impossible to achieve a burning plasma.

The solution came in 1982, when Friedrich Wagner (born 1943) discovered in Garching’s ASDEX fusion device a plasma state with particularly good properties, viz. the High-Confinement Regime or H-regime for short: Friedrich Wagner was able to show that under certain conditions self-organised transport barriers form at the plasma edge. The thermally insulating layer ensures good plasma confinement, this being a momentous discovery in the development of fusion research. Friedrich Wagner thus paved the way for further successes in the field: JET, the European large-scale experiment at Culham, UK, succeeded for the first time in the world in producing significant fusion power in the H-regime. This was also a prerequisite for planning the ITER international fusion test reactor, construction of which is to commence next year at Cadarache, France. This experiment is intended to demonstrate that a fusion plasma yielding energy is possible.

In 1986 Friedrich Wagner was appointed as project head of the ASDEX experiment, two years later as Scientific Fellow and Director at IPP. This was followed by his appointment as project head of Wendelstein 7-AS at Garching. In 1992 Wagner and his team also succeeded in developing the H-regime in this different type of device, the alternative stellarator concept: the H-regime had thus proved to be a universal plasma state.

From 2003 till 2005 Friedrich Wagner was in charge of the follow-up experiment, Wendelstein 7-X, at the Greifswald branch of IPP, whose spokesman he was from 1999 till 2007. Since 1999 Friedrich Wagner has been Professor of Physics at Ernst Moritz Arndt University in Greifswald, and since 2007 President of the European Physical Society.

Friedrich Wagner is now to retire at the end of this month. On 27 November 2008 IPP will mark the occasion with a festive colloquium entitled “A Quarter Century of H-mode Research”.

Isabella Milch