Wendelstein” nuclear fusion experiment at an important stage


A heat shield, expanded heating and new measuring instruments: after a 15-month conversion, the "wendelstein 7-X" nuclear fusion facility at the max planck institute for plasma physics in greifswald is now entering its second experimental phase.

The goal of the experiments, which will last until december, is to generate a fusion-relevant plasma in this facility for the first time, said institute director thomas klinger. According to the institute, nuclear fusion experts from all over the world have registered for the experiments. They want to explore fusion as a new primary energy source on earth in the greifswald plant.

The model for this is the sun, where the fusion of hydrogen nuclei into helium under high pressure and high temperatures releases gigantic amounts of energy. Nuclear fusion researchers are investigating the extent to which these physical processes on earth can be used in power plants to generate energy. Should this succeed, klinger said, fusion could become a base-load and CO2-free supplement to renewable energies in future decades.

At the end of 2015, the institute had generated the first plasma with the nuclear fusion facility. Since then, it has been possible to generate electron temperatures of up to 100 million degrees and ion temperatures of up to 20 million degrees in about 1000 different experiments in the plasma held by a magnetic ring. The machine's performance has now been upgraded to create fusion-relevant conditions. Under these conditions, atomic nuclei have already been able to fuse efficiently, said klinger. The electron and ion temperatures were then around 70 million degrees each. "Now we"re going full throttle."

Experiments with fusion fuel are not planned in the nuclear fusion experiment "wendelstein 7-X," which is required by the EU, the federal government and the state, now or in the future. Rather, the researchers want to make statements about the power plant suitability of the "stellerator" type facilities. "Wendelstein 7-X" is considered the world"s most modern research facility of this fusion type, the ? These are the assumptions of the greifswald researchers ? Be operated continuously in a power plant and thus be able to outperform the pulse-driven fusion type "tokamak. In the second phase of experiments, which is now beginning, the researchers want to generate plasmas at full heating power for up to ten seconds. The goal after further conversions is then to build plasmas for a duration of half an hour.

In the past few months, technicians had assembled a heat shield, placed with micrometer precision, from about 8,500 carbon tiles in the plant's plasma fab and installed so-called divertors ? These are special baffle plates made of graphite ? Installed. Klinger said that this would create the conditions for doubling the power of the microwave heating to 8.5 megawatts and subsequently generating higher plasma densities and temperatures. In addition, the central safety controls have been adapted to the more stringent experimental requirements and the magnetic fields have been configured for optimal confinement of the plasmas, added dirk naujoks, the technical director on duty at the facility.

About 100 researchers from abroad have signed up for the experiments ? Among others, the USA, spain, hungary, great britain and japan – have registered. They had previously submitted experiment proposals that were evaluated by an international commission. Among other things, the experiments are intended to answer questions about the stability of the plasma, the heating and the confinement of the plasma in the magnetic ring.

After the vacuum required for the experiments was created and the facility cooled down to minus 270 degrees near absolute zero, the test runs for the experiments have now been started, it was announced. The first "heibe" experiment is to take place at the beginning of september.

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