Tokamak Energy has announced the successful completion of tests of cryogenic power electronic technology for its superconducting magnets’ high-efficiency operation.
The company is working on fusion technology using a combination of spherical tokamaks and high-temperature superconducting (HTS) magnets. According to Tokamak Energy, tests of the new power electronics showed twice the efficiency of previous systems, resulting in a substantial reduction in the power required to cool the HTS magnets, lowering the cost of future fusion power plants, a critical step toward commercializing and scaling fusion technology.
Superconducting magnets are used in tokamak systems to concentrate and isolate plasma so that it can reach the high temperatures required for fusion. Cryogenic cooling is one of numerous energy issues. The new approach uses a higher-efficiency power converter within a vacuum cryostat.
In 2020, the U.S. Energy Department awarded Tokamak Energy multi-year funding, allowing the company to work with fusion experts within the U.S. national laboratory system. Its ST40 prototype is being developed in collaboration with Oak Ridge National Laboratory and Princeton Plasma Physics Laboratory. The U.K. government awarded a research grant as part of the Advanced Modular Reactor initiative.
Scientists initially recognized the potential of the tokamak design for achieving fusion conditions in the 1960s. The Russian T3 tokamak achieved plasma temperatures significantly greater than other fusion machines.
Alan Sykes, a co-founder Tokamak Energy, performed theoretical research in the 1980s, demonstrating that altering tokamak geometry boosted performance. Combining the improved efficiency of the spherical tokamak with better magnetic confinement provided by HTS magnet technology offered a potential path to commercial fusion.
Tokamaks rely on magnetic fields to trap electrically-charged plasma particles, confining fusion fuels. HTS magnets are composed of rare earth copper barium oxide fashioned into thin strips of less than 0.1-mm thickness. They can produce far greater magnetic fields while taking up less area when shaped into coils.
Tokamak Energy is working with the European Organization for Nuclear Research (CERN) to develop HTS magnets scalable to the size required for fusion power modules.
Tokamak Energy is developing two core technologies: The compact spherical tokamak and HTS magnets. “These enabling technologies are essential to the development of economic fusion,” said CEO Chris Kelsall.
The fusion power modules are designed to produce 500MW of heat or 150MW of electricity, the company claims. Heating plasma to temperatures of 100 million degrees Celsius are required for commercial fusion energy. Tokamak Energy is currently working to achieve that goal with its ST40 design. “If so, Tokamak Energy will be the first commercial fusion developer to achieve this key milestone in a controlled plasma,” Kelsall said. “However, we also believe there are other key ingredients which are essential to achieve commercial fusion.”
The ST40 design represents the company’s attempt to generate commercial fusion power. The machine reached a temperature of 15 million degrees Celsius in its first year of operation. The goal is demonstrating operation at 100 million degrees Celsius by overcoming repulsive forces between deuterium and tritium ions, bringing them close enough to fuse. Doing so would make ST40 the first privately-funded fusion machine capable of reaching the temperatures required for commercial fusion.
Tests of the new power converter suggest that system efficiency could be further improved. The company cites ways to halved the cost HTS magnets. A new power supply could provide continuous operation under 1,000-A, for example, and 2,000-A pulsed operation.
Kelsall predicts progress in 2022 by private fusion developers.
The recent Glasgow Climate Change Conference, or COP26, “reinforced the urgent need for new base-load sources of clean energy to be deployed globally, to replace carbon-intensive fossil fuels,” he noted.
Once commercialized, fusion energy will be clean, low-cost, secure, abundant, and safe. It offers the global community a transformational opportunity to reach and maintain net zero. The key role that fusion will play has been increasingly recognized by the global investor community, with considerable equity funding being deployed to private sector players in late 2021. This has arisen because many more investors have recognized that the sector is well-positioned to make a very significant contribution to the clean energy transformation — and seek exposure to the sector in diversified clean technology portfolio holdings.”
“The race to commercialize fusion will gather further pace next year as fusion companies make further technology advances,” Kelsall concluded. “Applications developed within the fusion sector will present substantial crossover opportunities in different industries, including aerospace, industry, and health care. 2022 will see the public and private sectors continue to work closely, to capitalize on the immense opportunities that fusion offers. This augurs well for the future.”
Many of the immediate engineering challenges for fusion are related to magnet technology. “The magnets must be powerful enough to contain a hot mass of matter, but not use so much electricity that the fusion reactor uses more power than it generates. Tokamak Energy has produced its own super-conducting high-temperature magnets that exert immense pressure on plasma and can be used not just for commercializing fusion but also for further applications such as aerospace,” said Kelsall.
According to Tokamak Energy, fusion is a zero-carbon energy source that creates no long-lived radioactive waste and can supply cost-competitive energy, according to research. Because of fusion’s inherent safety characteristics, site requirements are less strict than for conventional nuclear power, allowing deployment closer to population and industrial centers. Compact fusion also offers the advantage of being less expensive and quicker to build and deploy, as well as being able to fully use cutting-edge materials and technology.
[ This article has been edited. It was originally published with an incorrect byline. -ed. ]