QSE

Energy Physics Engineering
Advanced Fusion Reactor Engineering

Front Line Research
We propose a remountable (demountable) high-temperature superconducting magnet, and our laboratory is pursuing its design and development.

The innovative idea of splitting up massive superconducting magnet coils elicits new possibilities.

The heart of a nuclear fusion reactor is its core. In the core, deuterium and tritium are formed into plasma, which is then heated to a high-temperature of over 100 million degrees to induce a nuclear fusion reaction. However, a container made with a material that can withstand 100 million degrees does not exist with current technology. Therefore, a fusion reactor confining plasma in magnetic field has been proposed, which utilizes property of charged particles spiraling along magnetic field lines. This is called a magnetic confinement fusion reactor.

The superconducting magnet which creates a strong magnetic field inside the nuclear fusion reactor has a massive and complex structure that makes its production cost high. In addition, as it is difficult to gain access to apparatuses inside the reactor, a superconducting magnet is disadvantageous in terms of maintenance. The technology that resolves this issue is the remountable high-temperature superconducting magnet devised by Professor Hashizume. A characteristic of a superconductor is that, as the temperature decreases, its electrical resistance becomes zero, but if the magnet is split up, resistance occurs at the joined area. We conduct research in order to overcome this difficult problem through an engineering approach, considering the structural optimizations of the joined surface and superconducting conductor, and development of advanced cooling technique, among others.

Front Line Research

This is the remountable high-temperature superconducting magnet prototype devised by Associate Professor Ito.

Front Line Research

Experiment for the advanced cooling technique of cryogenic coolants

We have achieved world-class results in our experiments with high-temperature superconductors.

Low temperature superconductors which are cooled to an absolute temperature of 4 Kelvin (-269° Celsius) in liquid helium are used in existing experimental nuclear fusion reactor apparatuses. However, the remountable high-temperature superconducting magnet fabricated by Professor Hashizume requires a high-temperature superconductor and low resistance conductor-joint technology. When the conductor-joint technology developed by this laboratory was applied to the large-sized high-temperature superconducting conductor which was created in collaboration with the National Institute for Fusion Science, we were able to confirm that we can achieve low resistance applicable to nuclear fusion reactors, and we have also successfully achieved a current of 100,000 amperes at an absolute temperature of 20 Kelvin (-253° Celsius). This is a world-class result that we can be proud of, and it is a revolutionary technology that is one big step forward towards the practical use of nuclear fusion reactors.

In addition, the fabrication technology for this kind of large-sized high-temperature superconducting magnet is expected to provide innovative manufacturing methods for high-temperature superconducting devices for industrial use such as superconducting magnetic levitation railway and medical accelerators.

Professor Hashizume says, "There is no meaning in research that does not benefit society." This is why he constantly says, "Workers who have ceased thinking and only do as they are told are of no use. Researchers need to be able to think by themselves and take the initiative to act." This philosophy is what makes this laboratory appealing.

Front Line Research

Fabricating a large-sized high-temperature superconductor sample at the Superconducting Magnet System Laboratory in the National Institute for Fusion Science.

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