磁约束核聚变能研究进展、挑战与展望

Progress,challenge,and perspective of the development of magnetic confinement fusion energy

当前,能源安全、环境和气候变化等问题成为21世纪面临的最严峻挑战.核聚变能具有资源丰富、环境友好、固有安全等突出优势,是目前认识到的解决人类社会能源与环境问题的根本途径之一[1,2].因此,像核聚变能这样的新能源的研发一直为公众和行业所关注.特别是,美国国家点火装置(National Ignition Facility,NIF)在2022年12月的实验中实现了能量增益达到1.53倍.

Nuclear fusion energy is one of the potential solutions for realizing a future low-carbon energy as it is abundant in source,safe,and environmentally friendly.Although remarkable progress has been made in the past few decades,the realization of fusion energy remains challenging.Recently,breakthrough progress in the field of inertial fusion at NIF in the US has attracted considerable public attention.However,it seems that magnetic confinement fusion(MCF)seemingly remains the most promising path to fusion energy.In the last five decades,significant progress has been achieved in the field of MCF using the tokamak configuration.Major tokamaks in the world,such as TFTR,JT-60U,and JET have made notable contributions toward D-T burning experiments and in achieving high performance of plasma that is close to the ignition.All these advances have laid the foundation for the International Thermonuclear Experimental Reactor(ITER).As the most advanced international scientific,technological,engineering,and management project in human history,ITER will be the first reactor-level fusion facility and the most important bridge between current technology and engineering and those required to realize the DEMO fusion reactor.Meanwhile,in China,significant achievements have been made in the field of MCF with domestic tokamaks,such as HL-2A,EAST and HL-2M.A novel fueling technology—SMBI was developed in HL-2A,steady plasma operation for 1,000 s and H-mode operation for over 400 s were realized in EAST,and 1.15 MA plasma current was achieved in HL-2M with a potential capacity of over 3 MA.The participation in ITER and the undertaking of related procurement activities as a partner greatly promote the development of fusion technology in China.However,there are several obstacles to achieving fusion energy,and the three most notable obstacles pertain to plasma burning,fusion materials,and tritium self-sufficiency.Regarding burning plasma,the key concern is an insufficient understanding of the behavior of alpha particles in the fusion reactor core.For fusion materials,which include structural and plasma-facing materials,the critical issue pertains to the availability of a suitable neutron source that can be used to test and examine materials irradiated to desired neutron fluences in a fully integrated fusion environment.For tritium selfsufficiency,a high tritium-breeding ratio of the breeding blanket along with a sufficiently high tritium-burning ratio should be achieved,while the period for tritium recycling should be short enough.Furthermore,all these processes and technologies should be experimentally verified with the tritium breeding blanket.The ITER device addresses plasma burning,plasma support technology,and some issues of breeding blankets for tritium self-sufficiency.However,it does not provide substantial aid in overcoming challenges related to fusion materials.Moreover,predicting a schedule or outlining the roadmap of fusion energy has always been difficult.Herein,a concise roadmap for realizing fusion energy in China is presented.Although it is slightly aggressive,realizing fusion energy in the expected time with the efforts of scientists and the support of all sectors of society is possible.