Today’s extreme electromagnets in fusion experiments create monumental magnetic fields, but they are very vulnerable to high-energy particles, of which many appear during fusion. Such electromagnets would not survive operation in a fusion power plant for very long. New electromagnets with niobium and tin superconductors can handle it.
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Older TFTR tokamak. Credit: US DOE / Wikimedia Commons.
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Tokamaks still play a significant role in the legendary fusion energy race. In their fusion reactors and similarly in other types of fusion devices, the high-energy plasma, where the fusion reactions should take place, holds an extremely strong magnetic field. It consists of very powerful electromagnets, which are an essential component of a fusion reactor.
At the same time, however, it is one of the major weaknesses of the entire fusion technology. Really hot neutrons emerge from the plasma cloud, which fly around like angry wasps, including the isolation of the fusion reactor electromagnets. They can damage this insulation, reduce the performance of electromagnets, and also significantly reduce their life.
Yuhu Zhai. Kredit: PPPL.
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Yuhu Zhai, head of research at Princeton Plasma Physics Laboratory (PPPL), admits what this means. We will not start fusion energy with current electromagnets. If we want to build and operate fusion power plants that run continuously for days, today’s electromagnets would not survive in them for very long. Such a fusion power plant is likely to produce many high-energy particles, more so than current fusion experiments.
Zhai et al. they offer a new type of magnet as a solution, in which they created a new type of superconductor from specially heated niobium and tin wires. A current can travel through such a superconductor practically without separation, and conductors made of this material do not need insulation. The resulting electromagnet would be less susceptible to damage by high-energy particles from the fusion plasma. Its performance should also be improved.
Logo. Kredit: PPPL.
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The advantage of the new type of electromagnet is that its production for practical use should be simpler and, most importantly, cheaper. These electromagnets can operate at higher current densities and take up less space in the tokamak and can generate stronger magnetic fields. According to Michael Zarnstorff of the PPPL leadership, this is revolutionary. Making magnets pure metal, without insulation, is a great idea to simplify the process and erase many weaknesses.
Literature:
Superconductor Science and Technology 34: 105003.
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