Objectives

Nuclear fusion power is expected to replace fossil fuels as an inexhaustible energy source. The following nuclear reaction is considered at present;

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Therefore, the output energy of 17.6MeV is totally gained from one reaction as the mass defect. The helium called "alpha particle", which is one of the fusion outputs, plays an absolutely important role in the steady state operation of fusion reactor as a source of the heat required to sustain the D-T reaction or the burning plasma. In order to fulfill the reactor conditions a high-performance plasma with the temperature of 20keV and the density of 1 1020m-3 is required with the energy confinement time of more than one second. In order to demonstrate the sustainment of D-T burning with alpha heating, ITER (International Thermonuclear Experimental Reactor) as a framework of International Collaboration is now being constructed in France toward the operation at the beginning of 2020.

For the final realization of fusion power reactor based on magnetic confinement, which confines high-temperature plasma using strong magnetic field generated by external coils, toroidal plasmas have been intensively studied in many countries of the world. With the recent progress in toroidal plasma research, high-performance plasma, which can give a bright prospect toward future fusion reactors, has become routinely obtainable, but only for short pulse discharges ( 10 seconds) in toroidal devices equipped with normal conducting magnetic coils. Based on the past results, the three countries, China, Japan and Korea (C-J-K), have recently built large toroidal devices called EAST (Experimental Advanced Superconducting Tokamak), LHD (Large Helical Device) and KSTAR (Korea Superconducting Tokamak Advanced Research) having superconducting magnetic coils, respectively, and have successfully started the academic research aimed at the steady-state operation of high-performance plasma, which is an inevitable subject for the realization of fusion reactor. At present, there is no such a toroidal device with a complete set of superconducting coils in the western countries of Europe and in the United States.

EAST at ASIPP (Academy of Science Institute of Plasma Physics) in China and KSTAR at NFRI (National Fusion Research Institute) in Korea are a TOKAMAK-type device which confines high-temperature plasma with the helical magnetic field produced as the synthesis of the toroidal magnetic field generated by the external toroidal coils and the poloidal magnetic field generated by the internal toroidal plasma current. Tokamak has been widely studied in many countries of the world due to well-established high performances of the core plasma and the simple structure of magnetic field based on the toroidal symmetry. The EAST tokamak is characterized by a long pulse discharge with successful current drive and edge plasma physics research using high-Z (Z: atomic number) plasma-facing components such as molybdenum and tungsten with high melting point. The KSTAR tokamak is characterized by the transport study on high-performance plasmas represented by H-mode (high confinement mode) discharge with edge transport barrier and the study for heat load mitigation of ELM (edge localized mode) activity in H-mode using various methods, e.g., pellet injection and stochastic magnetic filed excited by RMP (resonant magnetic field) coils and so on.

On the other hand, LHD at NIFS (National Institute for Fusion Science) in Japan is the largest HELICAL-type device, which confines the high-temperature plasma with the helical magnetic field generated by external helical coils alone. It is characterized by the steady state operation without the necessity of toroidal plasma current unlike tokamaks. Therefore, the properties of the LHD plasma are very distinctive and different from those of tokamak plasmas, e.g., the characteristic transport of high-energy particles based on three-dimensional magnetic configuration, the edge heat and particle transports based on inherently-equipped stochastic magnetic field and the disruption-free sustainment of long pulse plasma.

By conducting joint research using the three world-class superconducting toroidal devices with entirely unique features, various advanced researches on critical physics issues to be resolved are possible toward the steady state operation of high-performance plasma. Fusion research is 'Complexity Science' consisting of 'Plasma Physics' and 'Reactor Engineering'. When the physics issues mentioned above are solved through the collaboration researches among the three countries, engineering requirements for the realization of an attractive fusion reactor can be drastically reduced. It will lead to the earlier start of DEMO reactor in addition to the cost and size reductions. Therefore, the objectives of the present proposal are set to form a center of excellence of academic researches and to establish a scientific research network for the studies. The collaboration will be truly able to contribute to the world-class fusion research. The proposed joint project will be certainly able to promote further development of plasma physics studies and fusion researches conducted by the three countries of C-J-K.

National Institute for Fusion Science