11.1 Major Tokamak Experiments (ITER, JET, DIII-D)
3 min read•july 19, 2024
Tokamaks are the leading fusion reactor design, with major experiments pushing the boundaries of fusion science. , , and represent key milestones in the quest for fusion energy, each contributing unique insights and technologies.
These experiments showcase the progress in , heating, and control. From ITER's ambitious goals to JET's record-breaking achievements and DIII-D's flexible research platform, they pave the way for future fusion power plants.
Major Tokamak Experiments
Key features of ITER project
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- International collaboration involving 35 nations demonstrates scientific and technological feasibility of fusion energy
- Aims to produce with 500 MW power output
- Designed to achieve Q value (fusion power output / input power) of 10 or greater
- Q > 1 indicates more energy produced than consumed (breakeven point)
- Key features of ITER tokamak design:
- confine plasma at high temperatures (150 million ℃)
- Blanket modules shield components from neutrons and breed tritium fuel
- Divertor exhausts waste materials and impurities (helium ash)
- Heating systems (, radio frequency heating) heat plasma to fusion temperatures
- Objectives include demonstrating integrated operation of fusion power plant technologies (superconducting magnets, remote handling) and testing reactor components (first wall, divertor)
Achievements of JET experiment
- Joint European Torus (JET) is largest operational tokamak in the world (Culham Centre for Fusion Energy, UK)
- First tokamak to operate with (D-T) fuel mixture, planned fuel for future reactors
- Achieved record fusion power output of 16 MW in 1997 using D-T fuel
- Demonstrated feasibility of remote handling and maintenance, crucial for future reactors due to neutron activation of components
- Tested beryllium as plasma-facing material in vacuum vessel, improving plasma performance by reducing impurities
- Serves as testbed for ITER technologies (superconducting magnets) and operational scenarios ()
Role of DIII-D in fusion research
- DIII-D is medium-sized tokamak located at General Atomics in San Diego, California
- Focuses on advancing scientific understanding and optimization of tokamak performance
- Utilizes highly flexible and configurable design for studying wide range of plasma shapes and operating scenarios
- Key research areas:
- and confinement optimization improves fusion performance
- Development of advanced tokamak operating scenarios with improved performance (steady-state operation)
- Study of plasma-wall interactions and material erosion critical for reactor design
- Testing of plasma heating and current drive systems ()
- Contributions to ITER design and operation:
- Developed "" for steady-state operation
- Provides data for validating computational models used in ITER design (EFIT equilibrium reconstruction)
ITER vs JET vs DIII-D designs
- Size and scale:
- ITER: Largest tokamak under construction, designed for reactor-scale fusion performance
- JET: Largest currently operating tokamak, approximately 1/3 size of ITER
- DIII-D: Medium-sized tokamak, smaller than JET
- Magnetic field strength:
- ITER: 11.8 T using superconducting magnets
- JET: 3.45 T using copper magnets
- DIII-D: 2.2 T using copper magnets
- Plasma volume:
- ITER: 840 m³
- JET: 100 m³
- DIII-D: 20 m³
- Heating power:
- ITER: 50 MW planned
- JET: 38 MW
- DIII-D: 26 MW
- Fuel mixture:
- ITER: Designed for deuterium-tritium operation
- JET: Capable of deuterium-tritium operation
- DIII-D: Operates primarily with deuterium, no tritium capability
Key Terms to Review (20)
David Campbell: David Campbell is a notable figure in the field of nuclear fusion, particularly known for his contributions to major tokamak experiments. His work has significantly influenced the development and understanding of magnetic confinement fusion technologies and advanced reactor designs, impacting the progress of global initiatives aimed at achieving sustainable fusion energy.
Deuterium-Tritium: Deuterium-tritium (D-T) refers to a fusion reaction that occurs between deuterium, a hydrogen isotope with one neutron, and tritium, another hydrogen isotope with two neutrons. This fusion reaction is the most widely studied and is highly efficient, producing a significant amount of energy through the release of neutrons, making it a key focus for practical fusion energy applications.
DIII-D: DIII-D is a major tokamak facility located in San Diego, California, primarily focused on researching plasma physics and magnetic confinement for nuclear fusion. As one of the most prominent experimental devices in the world, DIII-D plays a crucial role in understanding plasma behavior, which informs the design and operation of future fusion reactors like ITER. Its experiments provide vital data on stability, confinement time, and energy efficiency that contribute to advancing fusion technology.
Electron Cyclotron Heating: Electron Cyclotron Heating (ECH) is a method of heating plasma in fusion reactors by using microwaves to excite the electrons in the plasma. This technique takes advantage of the cyclotron resonance, where electrons absorb energy from electromagnetic waves at specific frequencies that match their natural oscillation frequency, allowing for efficient heating. ECH is crucial for achieving the high temperatures required for nuclear fusion reactions and plays a significant role in enhancing plasma confinement and stability in various fusion experiments.
Eurofusion: Eurofusion is a European consortium aimed at advancing nuclear fusion research and development, primarily focusing on the ITER project and various other fusion experiments. It brings together numerous research institutes and organizations across Europe to collaborate on the goal of achieving sustainable and commercially viable fusion energy, thus addressing the global energy crisis.
First plasma: First plasma refers to the initial stage of plasma operation in a fusion reactor, where the reactor successfully produces a plasma for the first time. Achieving first plasma is a significant milestone in the development of fusion reactors, as it marks the transition from assembly and commissioning to actual operation and testing of plasma confinement and behavior.
H-mode: H-mode, or high-confinement mode, is a plasma operating regime in fusion research characterized by improved confinement of particles and energy compared to lower confinement modes. This enhanced performance is crucial for achieving the conditions necessary for ignition and sustained fusion reactions, as it significantly reduces the energy loss from the plasma. H-mode allows for better control of the plasma's stability, making it an essential aspect of advanced tokamak experiments.
International Thermonuclear Experimental Reactor: The International Thermonuclear Experimental Reactor (ITER) is a major international fusion research and engineering project aimed at demonstrating the feasibility of nuclear fusion as a large-scale and carbon-free source of energy. It represents a significant collaboration between multiple countries and aims to build the world's largest tokamak, a device that uses magnetic fields to confine hot plasma for fusion reactions. ITER is pivotal in the historical development of fusion research, marking a shift towards international cooperation in the quest for sustainable energy solutions.
ITER: ITER, which stands for International Thermonuclear Experimental Reactor, is a major international project aimed at demonstrating the feasibility of nuclear fusion as a large-scale and carbon-free energy source. This ambitious initiative is designed to address key challenges associated with fusion energy, providing insights into plasma confinement, energy generation, and the long-term viability of fusion power.
ITER Baseline Scenario: The ITER Baseline Scenario refers to a defined set of operational parameters and performance goals established for the International Thermonuclear Experimental Reactor (ITER) project. This scenario serves as a reference framework for achieving sustainable nuclear fusion reactions, focusing on plasma performance, energy output, and operational efficiency. The baseline scenario is crucial for guiding experimental designs and assessing the potential of fusion as a viable energy source.
Jean Michel: Jean Michel is a notable figure in the field of nuclear fusion, particularly known for his contributions to major Tokamak experiments, including ITER and JET. His work has been instrumental in advancing the understanding of plasma physics and engineering necessary for the development of fusion energy, which is considered a promising solution for future energy needs.
JET: The Joint European Torus (JET) is the largest and most advanced magnetic confinement fusion experiment in the world. It serves as a key facility for studying plasma behavior and testing technologies that will be used in future fusion reactors. JET has played a crucial role in advancing fusion research and understanding the conditions necessary for achieving sustained nuclear fusion.
Neutral Beam Injection: Neutral beam injection is a plasma heating and current drive technique used in fusion research, where neutral particles are accelerated and injected into the plasma to increase its energy and help sustain nuclear fusion reactions. This method is crucial for maintaining the high temperatures and pressures needed for fusion, as it allows for efficient energy transfer to the plasma without causing significant impurities.
Nuclear reaction: A nuclear reaction is a process in which two atomic nuclei or one nucleus and a subatomic particle collide, resulting in the transformation of the nuclei and the release or absorption of energy. These reactions are fundamental in both fission and fusion processes, where the conversion of mass to energy is described by Einstein's equation, $$E=mc^2$$. Understanding nuclear reactions is crucial for developing advanced fusion fuel concepts and evaluating the performance of major experimental reactors.
Plasma Confinement: Plasma confinement refers to the methods and techniques used to contain and stabilize plasma, the fourth state of matter, within a controlled environment to facilitate nuclear fusion reactions. Effective confinement is essential for achieving the high temperatures and pressures needed for fusion while minimizing energy losses and instabilities.
Plasma stability: Plasma stability refers to the ability of a plasma to maintain its confinement and structure without experiencing disruptive instabilities that can lead to loss of containment or energy. Achieving and maintaining stability is critical in fusion systems as it directly impacts plasma performance, energy output, and the longevity of the confinement device.
Pulse operation: Pulse operation refers to a mode of operation in fusion reactors, particularly tokamaks, where short bursts of plasma are created and maintained for a limited duration. This method allows researchers to investigate plasma behavior and confinement dynamics without the continuous energy input required for steady-state operation, making it essential for experiments focused on understanding the underlying physics of fusion reactions.
Superconducting Magnets: Superconducting magnets are powerful electromagnets made from materials that exhibit superconductivity, which allows them to conduct electricity without resistance at low temperatures. These magnets are essential in creating strong and stable magnetic fields necessary for various applications, particularly in fusion reactors where they help confine plasma and maintain stable operating conditions.
Sustained fusion reaction: A sustained fusion reaction is a continuous process where atomic nuclei combine to form heavier nuclei, releasing a significant amount of energy over an extended period. This process is crucial for achieving practical nuclear fusion energy, as it allows for the production of more energy than is consumed, making it a viable source for clean energy. In order for a sustained fusion reaction to occur, specific conditions of temperature, pressure, and confinement must be maintained over time.
Thermal Equilibrium: Thermal equilibrium refers to the state in which two or more systems or regions have reached a uniform temperature, resulting in no net heat transfer between them. This concept is crucial as it ensures that energy is balanced and stable within a system, impacting processes like energy confinement and plasma behavior. Achieving thermal equilibrium is essential for maintaining consistent conditions in fusion reactors and inertial confinement facilities.