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, tests of the new power electronics showed twice the efficiency of previous systems, resulting in a 50 percent reduction in the power required to cool the HTS magnets. Should fusion power plants ever be commercialized, minimizing the ultimate cost will of course be advantageous.
Researchers expect it will be necessary to heat a plasma to 100 million degrees Celsius and keep it at that temperature in order to achieve a self-sustaining fusion reaction.
Superconducting magnets are used in tokamak systems to concentrate and isolate plasma so that it can reach the high temperatures required for fusion, even as the superconducting magnets are cryogenically cooled.
A commercial fusion power generator is obligated to produce more energy than is input to trigger the fusion reaction. Halving the power necessary to cryogenically cool superconducting magnets helps with that calculation.
Tokamak Energy’s 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, but still far from a temperature high enough to sustain fusion.
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 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 concentrating on the two core technologies that Sykes’ research indicates: the compact spherical tokamak and HTS magnets.”These enabling technologies are essential to the development of economic fusion,” said Tokamak Energy CEO Chris Kelsall.
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.
“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.
Increasing the pressure counteracts the repulsive forces between deuterium and tritium ions, the goal being to get them close enough to fuse.
Kelsall predicts progress in 2022 by private fusion developers — not just Tokamak Energy. In the last 10 years or so, the number of fusion companies has roughly doubled; there are now over two dozen.
“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.”