Research&Development
14
October 2023
Started joint research with Associate Professor Motojima and his colleagues at the National Institute for Fusion Science on the development of a solid hydrogen pellet injector.
In a magnetic confinement fusion reactor, it is necessary to supply hydrogen isotope fuel particles to the high-temperature plasma. By cooling hydrogen isotopes to produce small grains of solid hydrogen, or solid hydrogen pellets, and injecting them into the plasma at high speeds of several hundred meters to one kilometer per second, fuel particles can be delivered close to the center of the plasma, where the fusion reaction is active. As a highly efficient fuel supply method, Helical Fusion and Associate Professor Motojima of the National Institute for Fusion Science have started joint research on the development of a pipe-gun type solid hydrogen pellet injector in which solid hydrogen pellets are generated in a metal tube and ejected by pressurized fuel hydrogen gas. The pellet injector will be equipped with a DIR (Direct Internal Recycling) function to purify, pressurize, and recycle the gas exhausted from the fusion reactor, and steady-state operation will be demonstrated.
13
October 2023
Started joint research with Associate Professor Yamaguchi, Associate Professor Satake, and Associate Professor Tamura at National Institute for Fusion Science on optimization of coil shape and current.
The shape and performance of the plasma in a helical fusion reactor depends on the shape of the helical and circular coils and the current of each coil. A more compact device can be designed if the space for blanket (the distance between the helical coils and the plasma) can be increased while improving the plasma performance. We have started a joint research project with Associate Professor Yamaguchi and his colleagues at National Institute for Fusion Science to optimize the shape and current of helical coils and circular coils using genetic algorithms.
12
August 2023
Started joint research with Assistant Professor Kobayashi of the National Institute for Fusion Science on the activation of fusion reactor blanket materials.
The fusion of deuterium D and tritium T, or DT fusion, is the easiest fusion reaction to cause in the universe. Helical Fusion believes that mankind, as a fusion novice, must be able to handle DT fusion as an energy source as a necessary step toward evolution. In DT fusion, 80% of the energy produced by the fusion reaction is released as neutron kinetic energy. These energetic neutrons are not captured by the magnetic field lines that confine the plasma but are ejected out of the plasma and absorbed by a device called a blanket that surrounds the plasma. Because of the enormous amount of heat that the blanket receives, Helical Fusion is developing a system in which liquid metal flows through the blanket to efficiently carry the heat out of the reactor. In this liquid metal blanket, liquid metal is poured into an enclosure made of structural materials such as steel or ceramics. Liquid metal and structural materials that are directly exposed to high-energy neutrons become radioactive. By properly selecting these materials, it is possible to attenuate the radioactivity over a short period (tens to a hundred years) and then reuse the materials. Such materials are called reduced activation materials. We have started joint research with Assistant Professor Kobayashi of the National Institute for Fusion Science to investigate numerical simulations to determine what kind of reduced activation materials should be selected for the liquid metal blanket of the helical fusion reactor to be developed by Helical Fusion.
11
August 2023
Started joint research with Assistant Professor Onodera of the National Institute for Fusion Science begin joint research on splicing methods for high-temperature superconducting WISE conductors
Helical Fusion is developing a high-temperature superconducting WISE conductor for fusion reactors. This WISE conductor is made by laminating and bundling high-temperature superconducting tape wires called REBCO. The length of the WISE conductor required to build a superconducting magnet for a helical fusion reactor is several tens of kilometers, but the currently available high-temperature superconducting tapes are at most a few kilometers long, so it is necessary to connect these conductors to make them longer. However, connecting high-temperature superconducting conductors to each other causes a slight resistance. Even for a superconducting magnet, loss due to Joule heating from this connection resistance is unavoidable, so the connection resistance must be kept as low as possible. Since the connection work is performed on-site during the winding of helical coils, etc., it must be as simple as possible. Assistant Professor Onodera of the National Institute for Fusion Science and his colleagues have started joint research on a splicing method for high-temperature superconducting WISE conductors that is both simple and achieves low splicing resistance.
10
June 2023
Started joint research with Professor Ishiyama at Waseda University on Development of Supercritical CO2 Turbine
Helical Fusion has started a joint research project with Dr. Ishiyama of Waseda University on the development of a power generation system using a supercritical CO2 turbine. Supercritical CO2 turbines can be smaller than steam turbines of the same output, and are also considered to have safety advantages.
09
May 2023
Started joint research with Associate Professor Satoshi Ito et al. at Tohoku University on a conductor surface treatment method for high-temperature superconducting conductor splicing.
Helical Fusion is developing a high-temperature superconducting WISE conductor for fusion reactors. This WISE conductor is made of a bundle of stacked high-temperature superconducting tapes called REBCO. The length of the WISE conductor required to build a superconducting magnet for a helical fusion reactor is several tens of kilometers, while the currently available high-temperature superconducting tapes are only a few kilometers long, so it is necessary to connect these tapes to make them longer. However, connecting high-temperature superconducting tape wires to each other causes a slight resistance. Even for a superconducting magnet, loss due to Joule heating from this connection resistance is unavoidable, so the connection resistance must be kept as low as possible. We have started joint research with Associate Professor Ito and his colleagues at Tohoku University on the development of a method to reduce connection resistance by treating the surface of the high-temperature superconducting tape wires at the time of connection.
08
May 2023
Started joint research with Associate Professor Tamura of National Institute for Fusion Science to analyze electromagnetic forces acting on superconducting magnets.
Helical Fusion is developing a high-field helical fusion reactor that employs a high-temperature superconducting magnet that generates a high magnetic field to minimize the device size. The superconducting magnets, in which a large current flows in a high magnetic field, are subjected to extremely large electromagnetic forces, so a structural design that can sufficiently withstand these forces is required. We have started a joint research with Associate Professor Tamura of National Institute for Fusion Science on the structural design of superconducting magnets for helical fusion reactors to realize high magnetic fields.
07
February 2023
Started joint research with Associate Professor Kariya at the University of Tsukuba to develop a
gyrotron.
Helical Fusion is developing a helical fusion reactor that will be operated in a steady state for year-long. We have started the development of a gyrotron, which is used for auxiliary heating of the plasma, with Associate Professor Kariya of Tsukuba University. Electrons in the plasma are heated by radiofrequency waves in the GHz band emitted from the gyrotron. The magnetic field of a helical fusion reactor is larger than that of conventional plasma fusion experimental devices, so a gyrotron with a higher frequency than existing ones is required. In addition, the output power must also be large to generate and maintain steady-state plasma in a large fusion reactor for one year.
06
November 2022
Started joint research with Assistant Professor Hamaji at National Institute for Fusion Science to conduct experiments to realize a liquid metal first wall
Helical Fusion is conducting research on the plasma-facing surface of a liquid metal blanket, i.e., the first wall, which has a porous structure to form a free surface flow of liquid metal oozing out from the inside of the blanket to coat and protect the first wall. We will start joint research with Assistant Professor Hamaji of the National Institute for Fusion Science to realize a porous structure to form a free surface flow of liquid metal by using a small experimental apparatus.
05
November 2022
Started collaboration with Assistant Professor Hamaji and his colleagues at National Institute for Fusion Science to Develop Liquid Metal First Wall
When liquid metal flows in a magnetic field, it is braked and the direction of flow is changed due to magnetohydrodynamic (MHD) effects. In order to optimize the flow path in the liquid metal blanket, we will start joint research with Assistant Professor Narushima and his colleagues of the National Institute for Fusion Science, aiming at a computer simulation of MHD effects in liquid metal blankets.
04
November 2022
Started joint research with Assistant Professor Narushima at National Institute for Fusion Science to develop a high-temperature superconducting magnet
In a helical fusion reactor, a high-temperature superconducting magnet is used to generate a strong magnetic field to confine the plasma. We will start research and development with Assistant Professor Narushima of the National Institute for Fusion Science, aiming to demonstrate the world's largest-class high current density in a strong magnetic field equivalent to that of a fusion reactor by building a coil with WISE conductors made of laminated high-temperature superconducting tapes bundled with a metal spiral tube.
03
August 2022
Started joint research with Kasada Laboratory, Institute for Materials Research, Tohoku University for the development of non-magnetic low-activation materials.
For the blanket of the helical fusion reactor, it is desirable to use a non-magnetic, low-activation material that does not disturb the magnetic field that confines the plasma and reduces the amount of radioactive waste. The development of "low-activation high-manganese steel" by replacing the nickel and molybdenum contained in non-magnetic stainless steel (austenitic steel) with manganese, which decays radioactivity 10 times faster than nickel, is underway at the Institute for Materials Research, Tohoku University. I will start with members of Kasada Lab.
02
July 2022
Started joint research on liquid metal blanket three-dimensional neutron transport calculation with Professor Sakama of Tokushima University
Three-dimensional neutron transport calculation is performed using 3D CAD of a helical fusion reactor equipped with a liquid metal blanket, and radiation shielding performance, fuel production performance, material activation, etc. are evaluated.
01
July 2022
Started joint research with Professor Sugawara of Aoyama Gakuin University on maintenance and replacement of helical fusion reactor blankets by crane robots.
We will develop a crane robot that enables rapid maintenance and replacement of liquid metal blankets, which are important equipment in helical fusion reactors, with Sugawara Laboratory, which specializes in crane control. A heavy blanket is hung by a crane so that it can be moved quickly without shaking while precisely controlling its position so that it does not hit surrounding equipment.