In this blog post, we’ll explore whether fusion power can establish itself as a future energy source by examining everything from the principles of nuclear fusion—the process by which the Sun generates energy—to the characteristics of magnetic confinement and inertial confinement methods, as well as recent achievements in fusion research and the challenges that remain.

What is the Sun’s source of energy?

For humanity, the Sun is a massive source of energy and the very source of life. The Sun is enormous—its volume is about 1.3 million times that of Earth—and it continuously emits an immense amount of energy. For approximately 4.6 billion years, the Sun has been emitting light and heat to provide energy to Earth, serving as a vital driving force behind every process, from the origin of life to the development of humanity today. So how has the Sun been able to continuously emit energy for such a long time, and how will it continue to do so in the future? The secret lies in nuclear fusion. Simply put, nuclear fusion is the process by which light atomic nuclei fuse to form heavier atomic nuclei. During this process, a difference in mass occurs between before and after the reaction, and this mass deficit is converted into a massive amount of energy according to Einstein’s mass-energy equivalence principle, E=mc². In particular, when hydrogen nuclei fuse to form helium nuclei, a portion of the mass involved in the reaction is converted into energy. Scientists believed that if such nuclear fusion could be artificially induced on Earth and used as an energy source, it would be possible to obtain enormous amounts of energy, similar to the Sun, and research to realize fusion power generation continues actively to this day. Although nuclear fusion has not yet reached the stage of being used for commercial electricity production, important achievements demonstrating fusion reactions and energy amplification are being made one after another in laboratories.
Fundamentally, for nuclear fusion to occur, atomic nuclei must come very close to one another. However, since atomic nuclei contain protons, they carry a positive charge; consequently, an electrical repulsive force acts between them. Since electromagnetic forces are quite strong at the microscopic level, it is extremely difficult to overcome this repulsive force and bring atomic nuclei close together. However, if atomic nuclei are heated to ultra-high temperatures ranging from tens of millions to hundreds of millions of degrees Celsius, the kinetic energy of the particles becomes very high, increasing the likelihood that they can overcome the electrical repulsion and come close to one another. Once the atomic nuclei are sufficiently close, the strong nuclear force—which acts over very short distances—becomes dominant, and the atomic nuclei fuse to initiate a nuclear fusion reaction. The reaction primarily studied in nuclear fusion power generation is the fusion of deuterium and tritium. Deuterium is an isotope of hydrogen consisting of one proton and one neutron, while tritium is an isotope of hydrogen consisting of one proton and two neutrons. Deuterium is a stable isotope, but tritium is a radioactive isotope with a half-life of approximately 12.3 years. When the two atomic nuclei fuse, a helium nucleus—that is, an alpha particle—and a high-energy neutron are produced, releasing approximately 17.6 MeV of energy. The basic concept of fusion power generation is to harness the energy of the helium nucleus and neutron produced during this process to generate heat and, ultimately, electricity.
The nuclear fusion power generation methods currently under research can be broadly categorized into magnetic confinement and inertial confinement. Of course, since these technologies are still in the research and development stage, each method faces challenges that need to be addressed. Below, we will examine the principles by which each method induces nuclear fusion, the challenges they face, and the technologies currently being researched to overcome these challenges.

Can an Ultra-High-Temperature Plasma Be Contained by a Magnetic Field?

First, let’s examine the magnetic confinement method. The basic principle of magnetic confinement is relatively simple. Deuterium and tritium—isotopes of hydrogen—are fed into a fusion reactor and heated to extremely high temperatures, creating a plasma state in which atomic nuclei and electrons are separated. The reason deuterium and tritium are primarily used in fusion power generation is that, among various fusion fuels, the deuterium-tritium reaction achieves a high reaction rate at relatively low temperatures. While deuterium can be obtained from seawater, tritium exists in only very small quantities in nature, so a separate production technology is required. In future fusion power plants, so-called tritium breeding technology—which uses neutrons generated by the fusion reaction to produce tritium from lithium and reuse it as fuel—will be crucial.
Once the plasma is created, it is confined using strong magnetic fields to prevent it from coming into direct contact with the device’s walls. A representative example of such a device is the doughnut-shaped tokamak. In a tokamak, the external toroidal magnetic field combines with the poloidal magnetic field generated by the plasma current, forming helical magnetic field lines that allow the high-temperature plasma to be confined for extended periods. Additional heating devices are then used to raise the plasma temperature to a level where fusion reactions can occur actively. The basic concept of a future fusion power plant is that, once the fusion reaction is stably maintained, the energy generated during the reaction is recovered as heat in structures such as the blanket; this heat is then transferred using a coolant and converted into electricity via a steam turbine or other power generation system. In fact, experimental facilities such as ITER are currently researching magnetic confinement of high-temperature plasma and technologies for thermal and neutron shielding within the fusion reactor.
However, this process presents several significant challenges. Chief among these is the need to stably confine and control the high-energy alpha particles and neutrons generated during the fusion process, as well as the plasma, which reaches temperatures ranging from tens of millions to hundreds of millions of degrees Celsius. Because alpha particles are charged, they are influenced by magnetic fields. Therefore, alpha particles confined within the tokamak’s magnetic field can remain inside the plasma and transfer energy to it, which helps sustain the fusion reaction. In contrast, neutrons are electrically neutral and cannot be directly confined by a magnetic field. Neutrons escape from the plasma and reach the device’s walls and blanket, where their kinetic energy is converted into heat. Furthermore, in future fusion reactors, technology that uses a blanket containing lithium to absorb neutrons and produce tritium is crucial. In other words, neutrons are not merely something to be removed; they are also an important energy source that can be utilized to recover heat and produce tritium, a fusion fuel. However, since high-energy neutrons can damage structural materials and cause radiation contamination, issues regarding material durability and radiation contamination must be resolved.
The most challenging problem, however, is stably confining plasma reaching temperatures of tens of millions to hundreds of millions of degrees Celsius. In the early stages of fusion power technology development, it was believed that since plasma carries a charge, simply arranging magnetic coils in a doughnut shape to apply a magnetic field would be sufficient to keep the plasma securely contained within the doughnut. However, actual experiments confirmed that simply applying a magnetic field is insufficient to confine the plasma stably. Inside the tokamak, the position and shape of the plasma must be precisely controlled, and issues such as magnetohydrodynamic instabilities and “disruptions”—a phenomenon where the plasma suddenly loses its confinement—must also be resolved. Consequently, modern tokamaks have evolved beyond the use of simple doughnut-shaped magnetic coils; they now combine toroidal and poloidal magnetic fields to create a stable magnetic field structure while precisely controlling the plasma’s position and shape.
In a tokamak, an electric current is passed through the plasma to generate a poloidal magnetic field; this field then couples with the external toroidal magnetic field to form a helical magnetic field structure within the plasma. Therefore, rather than explaining the purpose of passing a current through the plasma simply as eliminating the electric potential within the plasma, it is more accurate to understand it as combining the magnetic field generated by the plasma current with the external magnetic field to form a magnetic field structure that stably confines the plasma. Of course, this method is not perfect either. Because tokamaks rely heavily on plasma current, sudden disruptions can occur, and to ensure stable, long-term operation, technologies such as plasma control, heating, materials, and heat removal must be developed in tandem. Nevertheless, the magnetic confinement method is currently one of the most mature approaches in fusion research and is being actively studied in various research facilities, including the International Thermonuclear Experimental Reactor (ITER) and South Korea’s KSTAR. In 2024, KSTAR achieved a 48-second run at a plasma ion temperature of 100 million °C and maintained H-mode—a high-performance plasma operating mode—for 102 seconds. Therefore, rather than describing the current level of magnetic confinement technology based solely on the single figure of 70 seconds—which was previously reported—it is necessary to also consider how long the plasma was sustained under specific temperature and operating conditions.

Can lasers trigger nuclear fusion?

Next, let’s examine the inertial confinement method. The inertial confinement method involves using powerful lasers to instantaneously compress a very small fusion fuel capsule. When powerful laser energy is focused on a fuel capsule containing deuterium and tritium, the outer layer of the capsule rapidly vaporizes and expands, compressing the internal fuel inward as a reaction. As the fuel is compressed into a high-density state for a very short period, the temperature and pressure at the core rise sharply, and if the appropriate conditions are met, a nuclear fusion reaction occurs. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in the United States, a leading research facility, is conducting research on this type of inertial confinement fusion.
This inertial confinement method faces two major challenges: the sustainability of energy output and power generation efficiency. Since the inertial confinement method triggers a fusion reaction by instantaneously compressing a single fuel capsule, utilizing it as a commercial power plant requires the ability to repeatedly supply fuel capsules at extremely high speeds, inject them into precise positions, and fire lasers continuously. Sustained power generation is only possible if the process—in which a new fuel capsule is inserted and a reaction is initiated after a fusion reaction has occurred—is repeated reliably. Furthermore, to determine the net power generation efficiency of an actual power plant, one must consider not only the energy obtained from the fusion reaction itself but also the total energy required to operate the lasers. Therefore, the fact that laboratory experiments have produced more fusion energy than the laser energy delivered to the fuel capsules is a different matter from the ability to supply net electricity to the grid at a power plant. In fact, even NIF’s experiments have not yet achieved net power generation at the power plant level when the facility’s total power consumption is taken into account.
In past experiments, the energy generated by fusion was very small compared to the laser energy, but the situation has changed significantly as technology has advanced rapidly. In 2022, the NIF achieved fusion ignition for the first time, producing more fusion energy than the laser energy delivered to the fuel, and has since succeeded in repeated ignition experiments. Notably, in an experiment on April 7, 2025, 2.08 MJ of laser energy was delivered to the fuel target, yielding 8.6 MJ of fusion energy, with a target gain of 4.13. Ignition experiments continued thereafter, and in June 2026, the team successfully conducted an ignition experiment that yielded 7.9 MJ of fusion energy. These results are highly significant in that they demonstrate that the inertial confinement approach goes beyond mere theoretical possibility and has repeatedly demonstrated the amplification of fusion energy in actual experiments. However, it is important to note that this is strictly a comparison between the laser energy delivered to the fuel target and the fusion energy produced; it must be distinguished from the net energy gain of a commercial power plant, which must account for the energy required to generate the lasers and operate the entire facility.
Although the inertial confinement approach still faces many challenges, its success in experimentally achieving fusion reactions and repeatedly meeting ignition conditions indicates significant potential for future development. In particular, as laser technology, fuel capsule fabrication technology, and precise control of the compression process continue to advance, the potential for achieving even higher energy gains is becoming increasingly evident. Therefore, rather than being merely a technology competing with magnetic confinement, the inertial confinement method can be viewed as an important field of research aimed at the practical application of fusion energy using different physical principles. Moving forward, it will be necessary not only to achieve high fusion energy in a single experiment but also to perform this repeatedly, supply fuel capsules at high speeds, and secure the technology to recover the generated heat and convert it into actual electricity.

Is Fusion Power Really Superior to Nuclear Power?

Currently, nuclear power is one of the key sources accounting for a significant portion of South Korea’s electricity production. Conventional nuclear power plants use the energy released when heavy atomic nuclei, such as uranium, undergo fission to heat water; the resulting steam then drives turbines to generate electricity. While nuclear fission power has the advantage of being able to produce large amounts of electricity reliably, it faces the problems of generating high-level radioactive waste during the fission process and the need for long-term management of spent nuclear fuel. In contrast, nuclear fusion power generates helium and neutrons through the fusion of deuterium and tritium, and does not produce the same type of long-lived, high-level radioactive waste generated by nuclear fission. However, fusion power is not entirely free from radiation-related issues. This is because tritium itself is a radioactive substance, and the high-energy neutrons produced during the fusion process can irradiate the reactor’s structural materials. Therefore, it is more accurate to understand fusion power not as a method that produces absolutely no radioactive waste, but as one that has the potential to significantly reduce long-lived high-level radioactive waste.
Furthermore, just because they are fusion fuels does not mean that both deuterium and tritium can be easily obtained from seawater. While deuterium is relatively abundant in seawater, tritium is a rare radioactive isotope that exists in only very small quantities in nature; therefore, technology to produce tritium in-house using lithium will be essential in future fusion power plants. When neutrons generated during the fusion process enter a blanket containing lithium, they can produce tritium; reusing this tritium as fusion fuel is one of the core fuel cycle systems in future fusion power plants. Therefore, fusion power generation is not a simple power generation method with an infinite fuel supply, but rather a comprehensive energy technology that requires the simultaneous resolution of various technical challenges, including deuterium supply, tritium production and recovery, lithium blankets, material radiation exposure and durability, heat recovery, and power conversion.
As such, fusion power has significant advantages over fission power, as it has the potential to greatly reduce long-lived high-level radioactive waste and to serve as a large-scale energy source that does not directly emit carbon. However, it cannot yet be definitively stated that the efficiency of fusion power is higher than that of conventional nuclear power, nor can it be claimed that it produces absolutely no radiation or radioactive waste. Above all, fusion power has not yet reached the stage of commercial electricity production, and challenges remain to be addressed, including the long-term stable maintenance of plasma, the durability of fusion reactor materials, self-sufficiency in tritium, heat recovery and power conversion, economic viability, and continuous operation. ITER, too, is not a power plant that directly produces fusion energy on a commercial scale, but rather a large-scale international experimental facility designed to validate these technologies; a key goal is to translate fusion energy into actual electricity production through future demonstration plants such as DEMO.
Nevertheless, the potential for fusion power generation is clearly growing. In magnetic confinement, technology for sustaining ultra-high-temperature plasma for extended periods using tokamaks is steadily advancing, while in inertial confinement, the National Ignition Facility (NIF) is repeatedly generating fusion energy far exceeding the laser energy delivered to the fuel, demonstrating the possibility of fusion ignition. At a time when securing a stable supply of energy resources and reducing carbon emissions have emerged as critical challenges, it is worth anticipating what technical breakthroughs fusion power generation might achieve in the future and whether it can lead to actual electricity production. However, rather than viewing fusion as a fully developed technology that will instantly solve humanity’s energy problems, it is most appropriate under current circumstances to regard it as a future energy technology—one that, while still facing unresolved challenges, is accumulating significant scientific and engineering achievements.