In plasma physics, a burning plasma is a plasma that is heated primarily by fusion reactions involving thermal plasma ions. [1] [2] The Sun and similar stars are a burning plasma, and in 2020 the National Ignition Facility achieved a burning plasma in the laboratory. [3] A closely related concept is that of an ignited plasma, in which all of the heating comes from fusion reactions.
The Sun and other similar stars are internally heated by fusion reactions involving hydrogen ions. The high temperatures needed to sustain fusion reactions are maintained by a self-heating process in which energy from the fusion reaction heats the thermal plasma ions via particle collisions. A plasma enters what scientists call the burning plasma regime when the self-heating power exceeds any external heating. [1]
The Sun is a burning plasma that has reached fusion ignition, meaning the Sun's plasma temperature is maintained solely by energy released from fusion. The Sun has been burning hydrogen for 4.5 billion years and is about halfway through its life cycle. [1]
Thermonuclear weapons, also known as hydrogen bombs, are nuclear weapons that use energy released by a burning plasma's fusion reactions to produce part of their explosive yield. This is in contrast to pure-fission weapons, which produce all of their yield from a neutronic nuclear fission reaction. The first thermonuclear explosion, and thus the first man-made burning plasma, was the Ivy Mike test carried out by the United States in 1952. All high-yield nuclear weapons today are thermonuclear weapons. [4]
In 2020, a burning plasma was created in the laboratory for the first time at the National Ignition Facility, a large laser-based inertial confinement fusion research device located at the Lawrence Livermore National Laboratory in Livermore, California. [3] NIF achieved a fully ignited plasma on August 8, 2021, [5] [6] [7] and a scientific energy gain above one on December 5, 2022. [8] [9]
Multiple tokamaks are currently under construction with the goal of becoming the first magnetically confined burning plasma experiment.
ITER, being built near Cadarache in France, has the stated goal of allowing fusion scientists and engineers to investigate the physics, engineering, and technologies associated with a self-heating plasma. Issues to be explored include understanding and controlling a strongly coupled, self-organized plasma; management of heat and particles that reach plasma-facing surfaces; demonstration of fuel breeding technology; and the physics of energetic particles. These issues are relevant to ITER's broader goal of using self-heating plasma reactions to become the first fusion energy device that produces more power than it consumes, a major step toward commercial fusion power production. [1] To reach fusion-relevant temperatures, the ITER tokamak will heat plasmas using three methods: ohmic heating (running electric current through the plasma), neutral particle beam injection, and high-frequency electromagnetic radiation. [1]
SPARC, being built in Devens in the United States, plans to verify the technology and physics required to build a power plant based on the ARC fusion power plant concept. [10] SPARC is designed to achieve this with margin in excess of breakeven and may be capable of achieving up to 140 MW of fusion power for 10-second bursts despite its relatively compact size. [10] SPARC's high-temperature superconductor magnet is intended to create much stronger magnetic fields, allowing it to be much smaller than similar tokamaks. [11]
The NIF burning plasma, despite not occurring in an energy context, has been characterised as a major milestone in the race towards nuclear fusion power, [12] [13] [14] with the perception that it could bring with it a better planet. [15] The first controlled burning plasma has been characterized as a critical juncture on the same level as the Trinity Test, with enormous implications for fusion for energy (fusion power), including the weaponization of fusion power, mainly for electricity for directed-energy weapons, as well as fusion for peacebuilding – one of the main tasks of ITER. [16] [17] [18]
A tokamak is a device which uses a powerful magnetic field generated by external magnets to confine plasma in the shape of an axially-symmetrical torus. The tokamak is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. The tokamak concept is currently one of the leading candidates for a practical fusion reactor.
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors. Research into fusion reactors began in the 1940s, but as of 2024, no device has reached net power, although net positive reactions have been achieved.
This timeline of nuclear fusion is an incomplete chronological summary of significant events in the study and use of nuclear fusion.
ITER is an international nuclear fusion research and engineering megaproject aimed at creating energy through a fusion process similar to that of the Sun. Upon completion of construction of the main reactor and first plasma, planned for late 2025, it will be the world's largest magnetic confinement plasma physics experiment and the largest experimental tokamak nuclear fusion reactor. It is being built next to the Cadarache facility in southern France. ITER will be the largest of more than 100 fusion reactors built since the 1950s, with ten times the plasma volume of any other tokamak operating today.
The National Ignition Facility (NIF) is a laser-based inertial confinement fusion (ICF) research device, located at Lawrence Livermore National Laboratory in Livermore, California, United States. NIF's mission is to achieve fusion ignition with high energy gain. It achieved the first instance of scientific breakeven controlled fusion in an experiment on December 5, 2022, with an energy gain factor of 1.5. It supports nuclear weapon maintenance and design by studying the behavior of matter under the conditions found within nuclear explosions.
The Lawson criterion is a figure of merit used in nuclear fusion research. It compares the rate of energy being generated by fusion reactions within the fusion fuel to the rate of energy losses to the environment. When the rate of production is higher than the rate of loss, the system will produce net energy. If enough of that energy is captured by the fuel, the system will become self-sustaining and is said to be ignited.
Magnetic confinement fusion (MCF) is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of controlled fusion research, along with inertial confinement fusion.
DEMO, or a demonstration power plant, refers to a proposed class of nuclear fusion experimental reactors that are intended to demonstrate the net production of electric power from nuclear fusion. Most of the ITER partners have plans for their own DEMO-class reactors. With the possible exception of the EU and Japan, there are no plans for international collaboration as there was with ITER.
DIII-D is a tokamak that has been operated since the late 1980s by General Atomics (GA) in San Diego, USA, for the U.S. Department of Energy. The DIII-D National Fusion Facility is part of the ongoing effort to achieve magnetically confined fusion. The mission of the DIII-D Research Program is to establish the scientific basis for the optimization of the tokamak approach to fusion energy production.
The tokamak à configuration variable is an experimental tokamak located at the École Polytechnique Fédérale de Lausanne (EPFL) Swiss Plasma Center (SPC) in Lausanne, Switzerland. As the largest experimental facility of the Swiss Plasma Center, the TCV tokamak explores the physics of magnetic confinement fusion. It distinguishes itself from other tokamaks with its specialized plasma shaping capability, which can produce diverse plasma shapes without requiring hardware modifications.
An edge-localized mode (ELM) is a plasma instability occurring in the edge region of a tokamak plasma due to periodic relaxations of the edge transport barrier in high-confinement mode. Each ELM burst is associated with expulsion of particles and energy from the confined plasma into the scrape-off layer. This phenomenon was first observed in the ASDEX tokamak in 1981. Diamagnetic effects in the model equations expand the size of the parameter space in which solutions of repeated sawteeth can be recovered compared to a resistive MHD model. An ELM can expel up to 20 percent of the reactor's energy.
Ignitor is the Italian name for a planned tokamak device, developed by ENEA. As of 2022, the device has not been constructed.
Fusion ignition is the point at which a nuclear fusion reaction becomes self-sustaining. This occurs when the energy being given off by the reaction heats the fuel mass more rapidly than it cools. In other words, fusion ignition is the point at which the increasing self-heating of the nuclear fusion removes the need for external heating. This is quantified by the Lawson criterion. Ignition can also be defined by the fusion energy gain factor.
Robert James Goldston is a professor of astrophysics at Princeton University and a former director of the Princeton Plasma Physics Laboratory.
SPARC is a tokamak under development by Commonwealth Fusion Systems (CFS) in collaboration with the Massachusetts Institute of Technology (MIT) Plasma Science and Fusion Center (PSFC). Funding has come from Eni, Breakthrough Energy Ventures, Khosla Ventures, Temasek, Equinor, Devonshire Investors, and others.
The history of nuclear fusion began early in the 20th century as an inquiry into how stars powered themselves and expanded to incorporate a broad inquiry into the nature of matter and energy, as potential applications expanded to include warfare, energy production and rocket propulsion.
The Compact Ignition Tokamak (CIT) was a plasma physics experiment that was designed but not built. It was designed by an inter-organizational team in the US led by Princeton Plasma Physics Laboratory. The experiment was designed to achieve a self-sustaining Thermonuclear fusion reaction (ignition) in a Tokamak with the minimum possible budget.
Andrea Lynn "Annie" Kritcher is an American nuclear engineer and physicist who works at the Lawrence Livermore National Laboratory. She was responsible for the development of Hybrid-E, a capsule that enables inertial confinement fusion. She was elected Fellow of the American Physical Society in 2022.
Rajesh Maingi is a physicist known for his expertise in the physics of plasma edges and program leadership in the field of fusion energy. He is currently the head of Tokamak Experimental Sciences at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL). He is a Fellow of both the American Physical Society and the American Nuclear Society and has chaired or co-chaired numerous national and international conferences.
The shot at Lawrence Livermore National Laboratory on 5 December is the first-ever controlled fusion reaction to produce an energy gain.