Research for the Energy of the Future 2 Research Programme

Research for the Energy of the Future 2 Research Programme The research conducted by the fusion is an ionised, low-density gas – Max-Planck-Institut für Plasmaphysik a “plasma” – composed of the two hy- (IPP) at Garching and Greifswald with drogen isotopes, deuterium and tritium. its workforce of approx. 1,100 is aimed It has to be heated to an ignition tem- at in vestigating the basis for a fusion perature of 100 million degrees. The power plant. As in the sun, such a plant plasma therefore cannot be directly will generate energy from the fusion of confined in a mat e rial vessel. Any wall atomic nuclei. The raw materials need- contact would immediately re-cool the ed for the fusion process, deuterium hot, low-density gas. Instead, magnetic and lithium, are available in almost un- fields are applied to confine and ther- complex-shaped external coils. This al- limited quantities throughout the mally insulate the plasma and keep it lows stellarators to work in a continu- world. Since a fusion power plant also away from the vessel walls. ous mode. promises a high level of safety and fa - Fusion research currently concen- vourable environmental properties, nu- trates on devices of two types, the to - Tokamaks and stellarators clear fusion could make a sustainable con- ka mak and the stellarator. Both confine tribution to future world energy supply. the plasma in a ring-shaped mag netic Both of these devices are being field cage. In tokamaks, part of the inves ti gated at the Max-Planck-Institut A magnetic-field cage for field is generated by external magnet für Plas ma physik: Garching is operat- confining the fuel coils, the other part by an electric cur- ing the ASDEX Upgrade tokamak; rent flowing in the plasma. This cur- whereas the Greifswald branch is build - Like a wood fire, the fusion fire rent is induced in a pulsed mode by a ing the Wendelstein 7-X stellarator, does not burn by itself, but only under transformer. Stellarators, on the other which is to demonstrate whether the im- the appropriate ignition hand, operate with a proved stellarator concept developed at conditions. The fuel for field gene rated solely by IPP is suitable for use in a reactor. JET, the European joint experiment at Culham, UK IPP at Garching research site 3 European and international achieved a fusion power of 16 mega - Founded 1994 – the Greifswald branch of IPP cooperation in fusion research watts in deuterium-tri tium operation and succeeded in recovering, as fusion power of 500 megawatts – ten times as Within the context of the European energy, 65 per cent of the en ergy re- much as needed to heat the plasma – Fusion Programme, IPP is variously in- quired for plasma heating. and at the same time investigate tech - volved in the Joint European Torus IPP scientists are also involved in the nical components of a fusion power (JET) experiment at Culham, UK – in- next step on the way to a power plant, plant. cluding delegation of personnel. In the ITER (Latin for “the way”) experi- many respects the plasma of this, the mental reactor. This fusion device of world’s largest fusion device, al ready the tokamak type is being built at Cada - closely conforms to that of a power rache in France as an international co- plant. In 1997, the JET tokamak briefly operation. ITER is to produce a fusion The ITER international experimental reactor 4 Tokamaks The ASDEX Upgrade tokamak, Germany’s largest fusion device, has been operating at Garching since 1991. This experiment is aimed at investigat- ing key ques tions of fusion research under power-plant-like conditions. For this purpose, the plasma properties are adapted to the conditions that will pre- vail in a future fusion power plant. The device owes its name – Axially Sym- metric Divertor Experiment – to a special mag netic-field configuration, the divertor. This facility can influence the inter- Plasma of action between the hot fuel and the sur- ASDEX Upgrade rounding walls: the divertor field de- flects the outer boundary layer of the plasma to collector plates. This removes perturbing impurities from the plasma. At the same time, the vessel wall is pro- tected and good thermal insulation is achieved. These studies, both on ASDEX Upgrade and its predecessors ASDEX, have paved the way for the ITER experimental reactor. The ASDEX Upgrade tokamak: the plasma vessel Stellarators 5 The Wendelstein 7-A experiment stein 7-X, the magnetic field of which was the first in the world to demon- has been optimised to meet power plant strate the stellarator principle with a requirements. The device is now being hot plasma. Its successor was the Wen- built at the IPP branch institute in delstein 7-AS advanced stellarator. Greifs wald. The microwave heating for Fea turing an improved magnetic field, Wendelstein 7-X will be provided by the it was in operation in Garching from Karlsruhe Research Centre; the Jülich 1988 until 2002. Its 45 three-dimen- Research Centre is involved e.g. in the Plasma chamber of sionally shaped coils were also testing development of plasma diagnostics equip- Wendelstein 7-X a modular structure of the coil assem- ment. The 50 non-planar superconduct- bly for the first time. Wendelstein 7-AS ing magnet coils of Wendelstein 7-X has confirmed the basic optimisation are to demonstrate its essen tial stellara- principles and broken all records for stel- tor property, viz. continuous operation. larators of its size. The purpose is to show, with out yet pro- During construction of the device ducing an energy-yielding plasma, that numerical and theoretical studies con- the new stellarators are suitable for a tinued. These yielded the plans for the power plant. Information on energy follow-up experi- production is to be provided by the in- ment, Wendel - ternational ITER experiment. Construction of Wendelstein 7-X 6 Surface Physics The strong loads to which the inside IPP is also developing and testing Copper structure – surface of the plasma vessel is subject - new materials for fusion devices under material investigation for ed are being closely investigated at plasma load conditions. Particularly Wendelstein 7-X IPP. For example, high-energy plasma exposed sites require materials and particles can dislodge particles from coatings which – like, for example, Background image: the walls of the plasma vessel and thus tungsten-wire-reinforced tungsten com- sample of carbon-fibre- contaminate the plasma. This may also posites – are heat-resistent, thermally reinforced graphite cause erosion of the wall material and conductive and resistant to erosion. change its properties. Ultimately, hydrogen deposited on the wall can re-en- ter the plasma as a cold gas and cool it down. Plasma Heating 7 The plasma heating systems used in the fusion devices are also developed at IPP. The plasma is heated by firing high-energy neutral hydrogen atoms into it by means of injectors with powers of a few megawatts; the particle energy is transferred to the plasma via collisions. High-frequency waves are also used for heating: transmitter antennas at the plasma boundary or wave guides radiate large quantities of energy into the plasma at selected frequencies. Wave-guides for high-frequency heating of the plasma in the ASDEX Upgrade fusion experiment Cooperation with 8 Theory Universities Theoretical investigations are in- Major components of the micro - dispens able for evaluating experimental wave heating for the Wendelstein 7-X results. The computer simulation of the experiment are being developed at the physical processes involved is a major University of Stuttgart. In particular, feature of such studies: Theoretical they are planning and supervising pro- physicists at Garching and Greifswald duction of the transmission lines. In investigate and calculate the motion of conjunction with the University of plasma particles in the magnetic field Augsburg IPP are developing an ion and their confinement behaviour, equi- source for the heating of the ITER librium states of hot plasma, the origin plasma. Joint appointments link IPP of instabilities, and new types of mag- with the University of Greifswald and netic-field coils. the Technical Universities of Berlin and Munich. In addition, IPP scientists are involved as professors and lecturers in training students at eight other universities. Computer simula- Instability simulation for tions: instability a stellarator plasma and turbulence in the plasma Garching Technical Com puter Centre Services Energy Supply 9 Powerful computer systems are re- The projects constructing and oper- At Garching, the energy for the AS- quired to calculate magnetic fields, for ating the plasma experiments at IPP in DEX Upgrade device is supplied by the numerical simulation of plasma Garching and Greifswald use various re- large flywheel generators, the biggest of behav iour and for the fast acquisition sources provided by the technical ser- which can deliver a power of 150 mega - and evaluation of large quantities of vices. These include laboratories for watts for approx. ten seconds with a fly- experimental data. In collaboration electronics, materials research, high- wheel weighing 230 tons. For the long- with the Max Planck Society, IPP runs volt age and vacuum technology, design term discharges expected at Greifswald a computer centre at Garching for this offices and workshops for electrodeposi- Wendelstein 7-X will be supplied direct- purpose. The computer centre also pro- tion, mechanical, electrical and electron- ly from the high-voltage grid. vides computing capacity to many oth- ic production and building technology. er institutes of the Max Planck Society throughout Germany. Users have access to supercomputers – IBM p575 (Power 6) and BlueGene/P – as well as Linux clusters, supported by large mass stor- ages.

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