A dazzling white light rises from the end of the mountain range... "In the science fiction novel" The Three Body Problem, "the light emitted by the spacecraft's nuclear fusion engine is like the sun. By utilizing technologies such as nuclear fusion, humanity has moved beyond our home planet and into the vast universe. All things grow by the sun. The reason why the sun can emit light and heat is due to internal nuclear fusion reactions. Nuclear fusion energy has outstanding advantages such as abundant resources, environmental friendliness, and inherent safety, making it an ideal future energy source for humanity. If a 'sun' could be created to generate electricity, humanity could potentially achieve energy freedom. In 2024, seven departments including the Ministry of Science and Technology, the Ministry of Industry and Information Technology, and the State owned Assets Supervision and Administration Commission of the State Council jointly issued the "Implementation Opinions on Promoting Innovative Development of Future Industries", pointing out the need to strengthen the research and development of key core technologies for future energy represented by nuclear fusion. The ultimate goal of China's three-step strategy for nuclear energy development, which includes hot reactors, fast reactors, and fusion reactors, is to achieve the application of fusion energy. Controllable nuclear fusion, as a typical cutting-edge and disruptive technology, once applied in the future, will completely change the world energy landscape and ensure China's future energy security. The "artificial sun" comes from the "nucleus" and uses 1 liter of water to "release" the energy of burning 300 liters of gasoline. Nuclear fusion is the process of aggregating lighter atomic nuclei to produce heavier ones and releasing enormous amounts of energy. In 1952, the world's first hydrogen bomb was successfully tested, which made humanity realize the enormous energy of deuterium tritium fusion reactions. But hydrogen bomb explosions are uncontrollable nuclear fusion reactions that cannot provide stable energy output. From then on, humans have been committed to achieving artificially controlled nuclear fusion reactions (i.e. controlled nuclear fusion) on Earth, hoping to use the principle of solar radiation and heat to pave the way for energy freedom for humanity. Therefore, people also refer to experimental devices for controlled nuclear fusion research as "artificial suns". Deuterium tritium fusion, as an energy source, has significant advantages. Firstly, the fuel required for deuterium tritium fusion is extremely abundant on Earth. Deuterium is abundant in water, and about 0.035 grams of deuterium can be extracted per liter of water. Through fusion reactions, the energy equivalent to burning 300 liters of gasoline can be released; Tritium can be prepared by neutron bombardment of lithium, which is abundant in the Earth's crust, salt lakes, and seawater. Secondly, deuterium tritium fusion reactions do not produce harmful gases, have no highly radioactive activators, and are environmentally friendly. However, the conditions for the artificial sun to maintain its own combustion are very demanding. British scientist Lawson studied the threshold of this condition, also known as fusion ignition condition, in the 1950s. According to calculations, achieving observable deuterium tritium fusion requires an ion temperature greater than 100 million degrees Celsius, and the product of plasma density, temperature, and plasma energy confinement time ("triple product") is greater than 5 × 1021 kiloelectron volts per second per cubic meter. For decades, numerous nuclear fusion routes have been explored internationally. At present, there are three main ways to achieve nuclear fusion reactions: gravitational confinement, magnetic confinement, and inertial confinement. The sun, due to its massive mass, can undergo gravitational confinement nuclear fusion reactions in extremely high temperature and pressure environments through its immense gravity. On Earth, there are two main ways to achieve controllable nuclear fusion: magnetic confinement fusion and laser inertial confinement fusion. Laser inertial confinement nuclear fusion can use laser as a driver to compress deuterium tritium fuel target pellets, achieving nuclear fusion ignition and combustion within the inertial confinement time of high-density fuel plasma. The method of using a strong magnetic field to confine plasma to control nuclear fusion reactants in a "magnetic cage" is called magnetic confinement nuclear fusion. The road is still full of challenges. "Steady state self-sustaining combustion" is the key to continuously obtaining fusion energy. Among many technological approaches, Tokamaks use a spiral magnetic field generated by plasma current and external magnet coils to confine fusion fuel ions. They are considered to be the first to realize the application of fusion energy, and are currently the world's largest R&D investment, closest to nuclear fusion ignition conditions, and most mature technological development path. Tokamak was originally invented by Azimovich and others at the Kurchatov Institute of the Soviet Union in the 1950s. It is a ring-shaped container that uses magnetic fields to confine charged particles for controlled nuclear fusion. Currently, over 50 tokamak devices of different scales have been built and operated in the world, each with its own geometric dimensions and plasma confinement performance. At present, the Tokamaks in operation in China mainly include conventional Tokamaks and spherical Tokamaks. Since the implementation of experiments on Tokamaks, the comprehensive parameters of plasma have been continuously improved, and the "triple product" has increased by several orders of magnitude, gradually approaching ignition conditions. The European JET and American TFTR devices have achieved deuterium tritium fusion power output, revealing the feasibility of the tokamak magnetic confinement controlled nuclear fusion route. In 2021-2023, JET set a world record for 69 megajoules of fusion energy output. Although breakthroughs have been made in tokamak magnetic confinement fusion research, the road ahead is still full of challenges. The steady-state self-sustaining combustion of core plasma is the key to continuously obtaining fusion energy, and there are five major issues that need to be addressed to achieve this goal. One is the problem of non induced current driving in plasma. The plasma current is composed of Ohmic driving current and non inductive driving current. Ohmic driving current is based on the principle of transformers, induced by changes in the external coil current of the plasma. For non induced current drive, a portion can be driven by external high-power microwaves and neutral particle beam injection, while the other portion comes from the "bootstrap current" generated by the plasma's own pressure gradient. In experiments, it is hoped that the higher the proportion of this current provided by the plasma itself, the better. The second issue is the feeding and ash discharge. Fusion plasma is confined within a vacuum chamber, forming a shape resembling a "donut". The plasma density and temperature are highest near the center of the "donut" axis, and lower towards the boundary parameters. The neutral gases deuterium and tritium injected by traditional feeding methods are difficult to penetrate deep into the plasma core, and their combustion efficiency is difficult to improve. At the same time, the core plasma fusion reaction produces a large amount of helium, also known as helium ash. Helium ash is prone to accumulate in the core, leading to plasma performance degradation and even causing plasma extinction. The third issue is the interaction between plasma and materials. During the operation of a fusion reactor, some high-energy particles may break through the constraints of the magnetic field and collide with the internal components of the fusion device, posing a threat to the materials of these components. Meanwhile, if the interaction between particles and materials during the operation of fusion reactors generates a large amount of impurities at the edge of the plasma, these impurities will dilute the concentration of fuel ions, significantly reducing the performance of fusion plasma and making it difficult to maintain stable fusion power. The fourth issue is the physics of alpha particles. Alpha particle is the alternative name for helium (carrying 3.5 million electron volts of energy), a charged particle product of deuterium tritium fusion. At present, due to the long-term lack of suitable experimental platforms for conducting relevant experiments, the depth of research on the physics of burning plasma alpha particles is not enough, and related scientific issues still need to be further verified on deuterium tritium fusion experimental devices. The fifth is the problem of large-scale magnetohydrodynamic instability and large-scale fracture control. There are still a large number of instabilities in fusion plasma, which can disrupt the safe and stable operation of nuclear fusion reactions to varying degrees. Exploring interdisciplinary artificial intelligence has emerged in recent years. In order to carry out research on the problem of "steady-state self-sustaining combustion", major international experimental devices are moving towards higher parameters. China's controllable nuclear fusion devices such as the China Circulation Series and the Eastern Super Ring have continuously made breakthroughs in operation. For example, the largest and most parameter capable China Circulation III has achieved high confinement mode operation with a plasma current of 1 million amperes for the first time, setting a record for the operation of magnetic confinement fusion devices in China. In 2023, the largest tokamak JT-60SA jointly built by the European Union and Japan also achieved a plasma discharge of 1 million amperes. In January 2025, Dongfang Super Ring set a high confinement mode plasma operation record of 1066 seconds. In recent years, artificial intelligence has demonstrated a powerful empowering role in the field of controllable nuclear fusion research. The application of cutting-edge technologies such as deep learning and diffusion models in scenarios such as accelerated computation of high-precision plasma simulation programs has brought about technological breakthroughs. In 2019, a research team from Harvard University and Princeton Plasma Physics Laboratory used a deep neural network model trained on the DIII-D tokamak device operating in the United States to warn of JET device rupture events with over 90% accuracy. In 2022, the DeepMind team under Google collaborated with the Swiss Federal Institute of Technology to use reinforcement learning agents to control limiters, conventional diverters, advanced diverters, and even dual ring plasma configurations on the TCV tokamak. In 2024, a research team from Korea's Central University and Princeton Plasma Physics Laboratory successfully predicted the probability of tearing mode instability growth using deep learning methods on KSTAR and DIII-D Tokamaks, and combined it with reinforcement learning algorithms to control the probability of tearing mode growth while increasing plasma pressure. Domestic institutions and universities have also conducted extensive exploration in the intersection of fusion and artificial intelligence. The Southwest Institute of Nuclear Industry Physics of China National Nuclear Corporation has applied artificial intelligence modules such as rupture prediction, equilibrium inversion proxy model, and real-time identification and control of edge local models to the control and operation of nuclear fusion devices, effectively solving some control problems. Looking ahead to the future, once controllable nuclear fusion is applied, it will provide humanity with abundant and clean ideal energy. Future technology in science fiction may become a reality with the support of controllable nuclear fusion. (The author is the director of the Fusion Science Institute at the Southwest Institute of Nuclear Industry, China National Nuclear Corporation) (Xinhua News Agency)