Fusion power - Knowledge

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related issue of plasma-wall surface conditions. Reducing hydrogen permeability is seen as crucial to hydrogen recycling and control of the tritium inventory. Materials with the lowest bulk hydrogen solubility and diffusivity provide the optimal candidates for stable barriers. A few pure metals, including tungsten and beryllium, and compounds such as carbides, dense oxides, and nitrides have been investigated. Research has highlighted that coating techniques for preparing well-adhered and perfect barriers are of equivalent importance. The most attractive techniques are those in which an ad-layer is formed by oxidation alone. Alternative methods utilize specific gas environments with strong magnetic and electric fields. Assessment of barrier performance represents an additional challenge. Classical coated membranes gas permeation continues to be the most reliable method to determine hydrogen permeation barrier (HPB) efficiency. In 2021, in response to increasing numbers of designs for fusion power reactors for 2040, the

3069:. The plant will be constructed from 2022 to 2025 and is intended to lead the way for commercial pilot plants in the late 2025s. The plant will be 70% of full scale and is expected to attain a stable plasma of 150 million degrees. In the United States, cost-sharing public-private partnership FPPs appear likely, and in 2022 the DOE announced a new Milestone-Based Fusion Development Program as the centerpiece of its Bold Decadal Vision for Commercial Fusion Energy, which envisages private sector-led teams delivering FPP pre-conceptual designs, defining technology roadmaps, and pursuing the R&D necessary to resolve critical-path scientific and technical issues towards an FPP design. Compact reactor technology based on such demonstration plants may enable commercialization via a fleet approach from the 2030s if early markets can be located. 3077: 3775:(W7-X). The W7-X stellarator began Operational phase 1 (OP1.1) on 10 December 2015, successfully producing helium plasma. The objective was to test vital systems and understand the machine's physics. By February 2016, hydrogen plasma was achieved, with temperatures reaching up to 100 million Kelvin. The initial tests used five graphite limiters. After over 2,000 pulses and achieving significant milestones, OP1.1 concluded on 10 March 2016. An upgrade followed, and OP1.2 in 2017 aimed to test an uncooled divertor. By June 2018, record temperatures were reached. W7-X concluded its first campaigns with limiter and island divertor tests, achieving notable advancements by the end of 2018. It soon produced helium and hydrogen plasmas lasting up to 30 minutes. 2338:

Unless the tritons are quickly removed, most of the tritium produced is burned in the reactor, which reduces the handling of tritium, with the disadvantage of producing more, and higher-energy, neutrons. The neutron from the second branch of the D-D reaction has an energy of only 2.45 MeV (0.393 pJ), while the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in greater isotope production and material damage. When the tritons are removed quickly while allowing the He to react, the fuel cycle is called "tritium suppressed fusion". The removed tritium decays to He with a 12.5 year half life. By recycling the He decay into the reactor, the fusion reactor does not require materials resistant to fast neutrons.

1485:: hydrogen is ionized and accelerated by an electric field to form a charged beam that is shone through a source of neutral hydrogen gas towards the plasma which itself is ionized and contained by a magnetic field. Some of the intermediate hydrogen gas is accelerated towards the plasma by collisions with the charged beam while remaining neutral: this neutral beam is thus unaffected by the magnetic field and so reaches the plasma. Once inside the plasma the neutral beam transmits energy to the plasma by collisions which ionize it and allow it to be contained by the magnetic field, thereby both heating and refueling the reactor in one operation. The remainder of the charged beam is diverted by magnetic fields onto cooled beam dumps. 3863:(DOE) provided a grant of $ 46 million to eight companies across seven states to support fusion power plant design and research efforts. This funding, under the Milestone-Based Fusion Development Program, aligns with objectives to demonstrate pilot-scale fusion within a decade and to develop fusion as a carbon-neutral energy source by 2050. The granted companies are tasked with addressing the scientific and technical challenges to create viable fusion pilot plant designs in the next 5–10 years. The recipient firms include Commonwealth Fusion Systems, Focused Energy Inc., Princeton Stellarators Inc., Realta Fusion Inc., Tokamak Energy Inc., Type One Energy Group, Xcimer Energy Inc., and Zap Energy Inc. 13394:

O.; Harder, N.; Hartmann, D.; Helander, P.; Heinemann, B.; Hirsch, M.; Höfel, U.; Hopf, C.; Ida, K.; Isobe, M.; Jakubowski, M. W.; Kazakov, Y. O.; Killer, C.; Klinger, T.; Knauer, J.; König, R.; Krychowiak, M.; Langenberg, A.; Laqua, H. P.; Lazerson, S.; McNeely, P.; Marsen, S.; Marushchenko, N.; Nocentini, R.; Ogawa, K.; Orozco, G.; Osakabe, M.; Otte, M.; Pablant, N.; Pasch, E.; Pavone, A.; Porkolab, M.; Puig Sitjes, A.; Rahbarnia, K.; Riedl, R.; Rust, N.; Scott, E.; Schilling, J.; Schroeder, R.; Stange, T.; von Stechow, A.; Strumberger, E.; Sunn Pedersen, T.; Svensson, J.; Thomson, H.; Turkin, Y.; Vano, L.; Wauters, T.; Wurden, G.; Yoshinuma, M.; Zanini, M.; Zhang, D. (August 1, 2019).

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launched its Socio-Economic Studies and Prospective Research and Development strands to investigate how such factors might affect commercialization pathways and timetables. Similarly, in April 2023 Japan announced a national strategy to industrialise fusion. Thus, fusion power may work in tandem with other renewable energy sources rather than becoming the primary energy source. In some applications, fusion power could provide the base load, especially if including integrated thermal storage and cogeneration and considering the potential for retrofitting coal plants.

897:, which is about one-millionth atmospheric density. This means that the temperature and/or confinement time must increase. Fusion-relevant temperatures have been achieved using a variety of heating methods that were developed in the early 1970s. In modern machines, as of 2019, the major remaining issue was the confinement time. Plasmas in strong magnetic fields are subject to a number of inherent instabilities, which must be suppressed to reach useful durations. One way to do this is to simply make the reactor volume larger, which reduces the rate of leakage due to 3499: 3197:. However, technological developments and private sector involvement has raised concerns over intellectual property, regulatory administration, global leadership; equity, and potential weaponization. These challenge ITER's peace-building role and led to calls for a global commission. Fusion power significantly contributing to climate change by 2050 seems unlikely without substantial breakthroughs and a space race mentality emerging, but a contribution by 2100 appears possible, with the extent depending on the type and particularly cost of technology pathways. 1568:

been perfected. However, the operating environment of a commercial fusion reactor will be harsher for diagnostic systems than in a scientific reactor because continuous operations may involve higher plasma temperatures and higher levels of neutron irradiation. In many proposed approaches, commercialization will require the additional ability to measure and separate diverter gases, for example helium and impurities, and to monitor fuel breeding, for instance the state of a tritium breeding liquid lithium liner. The following are some basic techniques.

15791: 15671: 869: 3385: 16093: 15296: 3707: 3538: 1716: 16259: 15567: 3715: 1001: 16300: 16064: 15924: 15683: 1915: 2700:, which is fed back into the reactor as fuel. Hydrogen is flammable, and it is possible that hydrogen stored on-site could ignite. In this case, the tritium fraction of the hydrogen would enter the atmosphere, posing a radiation risk. Calculations suggest that about 1 kilogram (2.2 lb) of tritium and other radioactive gases in a typical power station would be present. The amount is small enough that it would dilute to legally acceptable limits by the time they reached the station's 16327: 16156: 16105: 16047: 16007: 15966: 15912: 15729: 15308: 3338: 3526: 15520: 18184: 15766: 15647: 15532: 15508: 3470: 15865: 4235: 18463: 16247: 15555: 15396: 341: 15831: 15608: 3483: 15379: 16288: 16271: 15995: 15659: 15591: 1821: 18172: 4249: 15954: 15625: 16224: 15853: 15803: 15484: 15467: 18196: 231: 908:, the initial frozen hydrogen fuel load has a density less than water that is increased to about 100 times the density of lead. In these conditions, the rate of fusion is so high that the fuel fuses in the microseconds it takes for the heat generated by the reactions to blow the fuel apart. Although NIF is also large, this is a function of its "driver" design, not inherent to the fusion process. 2769:

Each power circuit includes 154 individual magnets, and should a quench event occur, the entire combined stored energy of these magnets must be dumped at once. This energy is transferred into massive blocks of metal that heat up to several hundred degrees Celsius—because of resistive heating—in seconds. A magnet quench is a "fairly routine event" during the operation of a particle accelerator.

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more tritium, limiting its availability for fusion and increasing the risk of hazardous accumulation, complicating tritium management. Furthermore, the chemical and physical sputtering of SiC remains significant, contributing to tritium buildup through co-deposition over time and with increasing particle fluence. As a result, carbon-based materials have been excluded from

2669:. It requires precise and controlled temperature, pressure and magnetic field parameters to produce net energy, and any damage or loss of required control would rapidly quench the reaction. Fusion reactors operate with seconds or even microseconds worth of fuel at any moment. Without active refueling, the reactions immediately quench. 2941:

two months to start production and at least an additional week to generate a significant amount. This was considered to be enough time to detect a military use and to react with diplomatic or military means. To stop the production, a military destruction of parts of the facility while leaving out the reactor would be sufficient.

2937:. The underlying redesign could be detected by regular design information verification. In the (technically more feasible) case of solid breeder blanket modules, it would be necessary for incoming components to be inspected for the presence of fertile material, otherwise plutonium for several weapons could be produced each year. 2284:

protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, use lithium inside the reactor core as a design element. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this design was demonstrated in the

2405:. Theoretically, the most reactive aneutronic fuel is He. However, obtaining reasonable quantities of He implies large scale extraterrestrial mining on the Moon or in the atmosphere of Uranus or Saturn. Therefore, the most promising candidate fuel for such fusion is fusing the readily available protium (i.e. a 13393:

Wolf, R. C.; Alonso, A.; Äkäslompolo, S.; Baldzuhn, J.; Beurskens, M.; Beidler, C. D.; Biedermann, C.; Bosch, H.-S.; Bozhenkov, S.; Brakel, R.; Braune, H.; Brezinsek, S.; Brunner, K.-J.; Damm, H.; Dinklage, A.; Drewelow, P.; Effenberg, F.; Feng, Y.; Ford, O.; Fuchert, G.; Gao, Y.; Geiger, J.; Grulke,

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and serious radiation damage to reactor components. Additionally, naturally occurring tritium is extremely rare. While the hope is that fusion reactors can breed their own tritium, tritium self-sufficiency is extremely challenging, not least because tritium is difficult to contain (tritium has leaked

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First generation fusion plants are expected to use the deuterium-tritium fuel cycle. This will require the use of lithium for breeding of the tritium. It is not known for how long global lithium supplies will suffice to supply this need as well as those of the battery and metallurgical industries. It

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Ceramic materials such as silicon carbide (SiC) have similar issues like graphite. Tritium retention in silicon carbide plasma-facing components is approximately 1.5-2 times higher than in graphite, resulting in reduced fuel efficiency and heightened safety risks in fusion reactors. SiC tends to trap

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under Uri Shumlak investigated the use of sheared-flow stabilization to smooth out the instabilities of Z-pinch reactors. This involves accelerating neutral gas along the axis of the pinch. Experimental machines included the FuZE and Zap Flow Z-Pinch experimental reactors. In 2017, British technology

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Multiple approaches have been proposed to capture the energy that fusion produces. The simplest is to heat a fluid. The commonly targeted D-T reaction releases much of its energy as fast-moving neutrons. Electrically neutral, the neutron is unaffected by the confinement scheme. In most designs, it is

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If reactors can be made to operate using only deuterium fuel, then the tritium replenishment issue is eliminated and neutron radiation damage may be reduced. However, the probabilities of deuterium-deuterium reactions are about 20 times lower than for deuterium-tritium. Additionally, the temperature

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handling. In January and March 2021, NRC hosted two public meetings on regulatory frameworks. A public-private cost-sharing approach was endorsed in the 27 December H.R.133 Consolidated Appropriations Act, 2021, which authorized $ 325 million over five years for a partnership program to build fusion

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However, fusion power may still have a role filling energy gaps left by renewables, depending on how administration priorities for energy and environmental justice influence the market. In the 2020s, socioeconomic studies of fusion that began to consider these factors emerged, and in 2022 EUROFusion

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Fusion reactors create far less radioactive material than fission reactors. Further, the material it creates is less damaging biologically, and the radioactivity dissipates within a time period that is well within existing engineering capabilities for safe long-term waste storage. In specific terms,

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The same constraints prevent runaway reactions. Although the plasma is expected to have a volume of 1,000 m (35,000 cu ft) or more, the plasma typically contains only a few grams of fuel. By comparison, a fission reactor is typically loaded with enough fuel for months or years, and no

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amounting to many meters per year, requiring redeposition of the sputtered material. The redeposition site generally does not exactly match the sputter site, allowing net erosion that may be prohibitive. An even larger problem is that tritium is redeposited with the redeposited graphite. The tritium

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is not used for energy transfer and material activation is reduced several thousand-fold. The optimum temperature for this reaction of 123 keV is nearly ten times higher than that for pure hydrogen reactions, and energy confinement must be 500 times better than that required for the D-T reaction. In

1084:: A number of magnetic mirrors are arranged end-to-end in a toroidal ring. Any fuel ions that leak out of one are confined in a neighboring mirror, permitting the plasma pressure to be raised arbitrarily high without loss. An experimental facility, the ELMO Bumpy Torus or EBT was built and tested at 1051:

Internal rings: Stellarators create a twisted plasma using external magnets, while tokamaks do so using a current induced in the plasma. Several classes of designs provide this twist using conductors inside the plasma. Early calculations showed that collisions between the plasma and the supports for

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impact other substances, typically a surface of the device, and transfer a portion of their kinetic energy to the other atoms. The rate of conduction is also based on the temperature and density. Radiation is energy that leaves the cloud as light. Radiation also increases with temperature as well as

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in the laboratory on August 8, 2021, for the first time in the 60+ year history of the ICF program. The shot yielded 1.3 MJ of fusion energy, an over 8X improvement on tests done in spring of 2021. NIF estimates that 230 kJ of energy reached the fuel capsule, which resulted in an almost 6-fold

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Fuel costs are low, but economists suggest that the energy cost for a one-gigawatt plant would increase by $ 16.5 per MWh for every $ 1 billion increase in the capital investment in construction. There is also the risk that easily obtained lithium will be used up making batteries. Obtaining it from

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of the surrounding regions. This pushes those regions into the normal state as well, which leads to more heating in a chain reaction. The entire magnet rapidly becomes normal over several seconds, depending on the size of the superconducting coil. This is accompanied by a loud bang as the energy in

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Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons would be only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from lithium resources and a somewhat softer

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are low because of competing physical effects, such as energy loss in the form of light radiation. Designs have been proposed to avoid the problems associated with the cage, by generating the field using a non-neutral cloud. These include a plasma oscillating device, a magnetically shielded-grid, a

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The diagnostics of a fusion scientific reactor are extremely complex and varied. The diagnostics required for a fusion power reactor will be various but less complicated than those of a scientific reactor as by the time of commercialization, many real-time feedback and control diagnostics will have

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plasma has to generate enough energy to overcome its energy losses. The amount of energy released in a given volume is a function of the temperature, and thus the reaction rate on a per-particle basis, the density of particles within that volume, and finally the confinement time, the length of time

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Laser advances included frequency-tripling crystals that transformed infrared laser beams into ultraviolet beams and "chirping", which changed a single wavelength into a full spectrum that could be amplified and then reconstituted into one frequency. Laser research cost over one billion dollars in

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Prioritizing weapon-grade material regardless of secrecy: The fastest way to produce weapon-usable material was seen in modifying a civil fusion power station. No weapons-compatible material is required during civil use. Even without the need for covert action, such a modification would take about

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In a plasma that is embedded in a magnetic field (known as a magnetized plasma) the fusion rate scales as the magnetic field strength to the 4th power. For this reason, many fusion companies that rely on magnetic fields to control their plasma are trying to develop high temperature superconducting

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Molodyk, A.; Samoilenkov, S.; Markelov, A.; Degtyarenko, P.; Lee, S.; Petrykin, V.; Gaifullin, M.; Mankevich, A.; Vavilov, A.; Sorbom, B.; Cheng, J.; Garberg, S.; Kesler, L.; Hartwig, Z.; Gavrilkin, S.; Tsvetkov, A.; Okada, T.; Awaji, S.; Abraimov, D.; Francis, A.; Bradford, G.; Larbalestier, D.;

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unexpectedly quenched during start-up operations in 2008, destroying multiple magnets. In order to prevent a recurrence, the LHC's superconducting magnets are equipped with fast-ramping heaters that are activated when a quench event is detected. The dipole bending magnets are connected in series.

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is widely regarded as the optimal material for plasma-facing components in next-generation fusion devices due to its unique properties and potential for enhancements. Its low sputtering rates and high melting point make it particularly suitable for the high-stress environments of fusion reactors,

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Structural material stability is a critical issue. Materials that can survive the high temperatures and neutron bombardment experienced in a fusion reactor are considered key to success. The principal issues are the conditions generated by the plasma, neutron degradation of wall surfaces, and the

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This reaction is also common in research. The optimum energy to initiate this reaction is 15 keV, only slightly higher than that for the D-T reaction. The first branch produces tritium, so that a D-D reactor is not tritium-free, even though it does not require an input of tritium or lithium.

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A current travels in the z-direction through the plasma. The current generates a magnetic field that compresses the plasma. Pinches were the first method for human-made controlled fusion. The z-pinch has inherent instabilities that limit its compression and heating to values too low for practical

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Fusion trapping (left) against temperature (bottom) for various fusion approaches as of 2021, assuming DT fuel Solid line corresponds to Q = ∞ for IFC (inertial confinement fusion). Dashed line corresponds to Q = 0.01 for IFC. Colored contours correspond to Q factors for MFC (magnetic confinement

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tend to be less than those from fission, so that the hazard decreases more rapidly. Whereas fission reactors produce waste that remains radioactive for thousands of years, the radioactive material in a fusion reactor (other than tritium) would be the reactor core itself and most of this would be

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the US announced a US global strategy to commercialize fusion energy. Then, in April 2024, Japan and the US announced a similar partnership, and in May of the same year, the G7 announced a G7 Working Group on Fusion Energy to promote international collaborations to accelerate the development of

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Inertial confinement is the use of rapid implosion to heat and confine plasma. A shell surrounding the fuel is imploded using a direct laser blast (direct drive), a secondary x-ray blast (indirect drive), or heavy beams. The fuel must be compressed to about 30 times solid density with energetic

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A current circles around the outside of a plasma column, in the theta direction. This induces a magnetic field running down the center of the plasma, as opposed to around it. The early theta-pinch device Scylla was the first to conclusively demonstrate fusion, but later work demonstrated it had

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Approaches to fusion, in color coded families: Pinch Family (orange), Mirror Family (red), Cusp Systems (violet), Tokamaks & Stellarators (Green), Plasma Structures (gray), Inertial Electrostatic Confinement (dark yellow), Inertial Confinement Fusion (ICF, blue), Plasma Jet Magneto Inertial

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Pedersen, T. Sunn; Otte, M.; Lazerson, S.; Helander, P.; Bozhenkov, S.; Biedermann, C.; Klinger, T.; Wolf, R. C.; Bosch, H. -S.; Abramovic, Ivana; Äkäslompolo, Simppa; Aleynikov, Pavel; Aleynikova, Ksenia; Ali, Adnan; Alonso, Arturo; Anda, Gabor; Andreeva, Tamara; Ascasibar, Enrique; Baldzuhn,

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Tungsten's sputtering rate is orders of magnitude smaller than carbon's, and tritium is much less incorporated into redeposited tungsten. However, tungsten plasma impurities are much more damaging than carbon impurities, and self-sputtering can be high, requiring the plasma in contact with the

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In a production setting, the neutrons would react with lithium in the breeding blanket composed of lithium ceramic pebbles or liquid lithium, yielding tritium. The energy of the neutrons ends up in the lithium, which would then be transferred to drive electrical production. The lithium blanket

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The fusion reaction rate increases rapidly with temperature until it maximizes and then gradually drops off. The deuterium-tritium (D-T) fusion rate peaks at a lower temperature (about 70 keV, or 800 million kelvin) and at a higher value than other reactions commonly considered for fusion

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reported that researchers at the National Ignition Facility had achieved a net energy gain from a fusion reaction. The reaction of hydrogen fuel at the facility produced about 3.15 MJ of energy while consuming 2.05 MJ of input. However, while the fusion reactions may have produced more than 3

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prototype tokamak reactors and development of new supply chains, a problem which will affect any kind of fusion reactor. Tokamak designs appear to be labour-intensive, while the commercialization risk of alternatives like inertial fusion energy is high due to the lack of government resources.

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as bringing online the first commercial reactors around 2050 and a rapid expansion after mid-century. Some scenarios emphasized "fusion nuclear science facilities" as a step beyond ITER. However, the economic obstacles to tokamak-based fusion power remain immense, requiring investment to fund

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In magnetic containment, strong fields develop in coils that are mechanically held in place by the reactor structure. Failure of this structure could release this tension and allow the magnet to "explode" outward. The severity of this event would be similar to other industrial accidents or an

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For long term use, each atom in the wall is expected to be hit by a neutron and displaced about 100 times before the material is replaced. High-energy neutrons produce hydrogen and helium via nuclear reactions that tend to form bubbles at grain boundaries and result in swelling, blistering or

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effect. If a particle follows the field line and enters a region of higher field strength, the particles can be reflected. Several devices apply this effect. The most famous was the magnetic mirror machines, a series of devices built at LLNL from the 1960s to the 1980s. Other examples include

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Roth, Joachim; Tsitrone, E.; Loarte, A.; Loarer, Th.; Counsell, G.; Neu, R.; Philipps, V.; Brezinsek, S.; Lehnen, M.; Coad, P.; Grisolia, Ch.; Schmid, K.; Krieger, K.; Kallenbach, A.; Lipschultz, B.; Doerner, R.; Causey, R.; Alimov, V.; Shu, W.; Ogorodnikova, O.; Kirschner, A.; Federici, G.;

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Steinetz, Bruce M.; Benyo, Theresa L.; Chait, Arnon; Hendricks, Robert C.; Forsley, Lawrence P.; Baramsai, Bayarbadrakh; Ugorowski, Philip B.; Becks, Michael D.; Pines, Vladimir; Pines, Marianna; Martin, Richard E.; Penney, Nicholas; Fralick, Gustave C.; Sandifer, Carl E. (April 20, 2020).

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J/yr (= 1 × 10 J/yr) and that this does not increase in the future, which is unlikely, then known current lithium reserves would last 3000 years. Lithium from sea water would last 60 million years, however, and a more complicated fusion process using only deuterium would have fuel for

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Another study concluded "...large fusion reactors—even if not designed for fissile material breeding—could easily produce several hundred kg Pu per year with high weapon quality and very low source material requirements." It was emphasized that the implementation of features for intrinsic

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Commercial facility: The production potential is significant. But no fertile or fissile substances necessary for the production of weapon-usable materials needs to be present at a civil fusion system at all. If not shielded, detection of these materials can be done by their characteristic

3168:, to regulate and commercialize fusion, respectively. Then, in April 2023, in a decision likely to influence other nuclear regulators, the NRC announced in a unanimous vote that fusion energy would be regulated not as fission but under the same regulatory regime as particle accelerators. 3836:

reported receiving $ 500 million in Series E funding for its seventh-generation Polaris device, designed to demonstrate net electricity production, with an additional $ 1.7 billion of commitments tied to specific milestones, while Commonwealth Fusion Systems raised an additional $

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A beam of high energy particles fired at another beam or target can initiate fusion. This was used in the 1970s and 1980s to study the cross sections of fusion reactions. However beam systems cannot be used for power because keeping a beam coherent takes more energy than comes from

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Bagryansky, P. A.; Shalashov, A. G.; Gospodchikov, E. D.; Lizunov, A. A.; Maximov, V. V.; Prikhodko, V. V.; Soldatkina, E. I.; Solomakhin, A. L.; Yakovlev, D. V. (May 18, 2015). "Threefold Increase of the Bulk Electron Temperature of Plasma Discharges in a Magnetic Mirror Device".

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Sunn Pedersen, T.; Andreeva, T.; Bosch, H. -S; Bozhenkov, S.; Effenberg, F.; Endler, M.; Feng, Y.; Gates, D. A.; Geiger, J.; Hartmann, D.; Hölbe, H.; Jakubowski, M.; König, R.; Laqua, H. P.; Lazerson, S.; Otte, M.; Preynas, M.; Schmitz, O.; Stange, T.; Turkin, Y. (November 2015).

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Over time, the "advanced tokamak" concept emerged, which included non-circular plasma, internal diverters and limiters, superconducting magnets, operation in the "H-mode" island of increased stability, and the compact tokamak, with the magnets on the inside of the vacuum chamber.

1855:. This device has a cathode inside an anode wire cage. Positive ions fly towards the negative inner cage, and are heated by the electric field in the process. If they miss the inner cage they can collide and fuse. Ions typically hit the cathode, however, creating prohibitory high 3256:

deuterium-uranium tritium-generating heavywater nuclear plants and even build new ones, guaranteeing a supply of tritium into the 2070s, while the UKAEA would test breeder materials and simulate how tritium could be captured, purified, and injected back into the fusion reaction.

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source began to attract a raft of companies and investors. Over two dozen start-up companies attracted over one billion dollars from roughly 2000 to 2020, mainly from 2015, and a further three billion in funding and milestone related commitments in 2021, with investors including

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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.

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Fusion power has a number of disadvantages. Because 80 percent of the energy in any reactor fueled by deuterium and tritium appears in the form of neutron streams, such reactors share many of the drawbacks of fission reactors. This includes the production of large quantities of

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is expected that second generation plants will move on to the more formidable deuterium-deuterium reaction. The deuterium-helium-3 reaction is also of interest, but the light helium isotope is practically non-existent on Earth. It is thought to exist in useful quantities in the

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Subsequently, the UK Regulatory Horizons Council published a report calling for a fusion regulatory framework by early 2022 in order to position the UK as a global leader in commercializing fusion power. This call was met by the UK government publishing in October 2021 both its

1432:-based reactor. The system was able to manipulate the magnetic coils to manage the plasma. The system was able to continuously adjust to maintain appropriate behavior (more complex than step-based systems). In 2014, Google began working with California-based fusion company 2707:

The likelihood of small industrial accidents, including the local release of radioactivity and injury to staff, are estimated to be minor compared to fission. They would include accidental releases of lithium or tritium or mishandling of radioactive reactor components.

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revealed its projectile fusion project, which fires an aluminum disc at a fusion target, accelerated by a 9 mega-amp electrical pulse, reaching speeds of 20 kilometres per second (12 mi/s). The resulting fusion generates neutrons whose energy is captured as heat.

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Although tritium is volatile and biologically active, the health risk posed by a release is much lower than that of most radioactive contaminants, because of tritium's short half-life (12.32 years) and very low decay energy (~14.95 keV), and because it does not

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the UK is working with Canada and Japan in this regard. Meanwhile, in February 2024 the US House of Representatives passed the Atomic Energy Advancement Act, which includes the Fusion Energy Act, which establishes a regulatory framework for fusion energy systems.

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The widespread adoption of non-nuclear renewable energy has transformed the energy landscape. Such renewables are projected to supply 74% of global energy by 2050. The steady fall of renewable energy prices challenges the economic competitiveness of fusion power.

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is an abnormal termination of magnet operation that occurs when part of the superconducting coil exits the superconducting state (becomes normal). This can occur because the field inside the magnet is too large, the rate of change of field is too large (causing

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devices. The process converts a large fraction of the random energy of the fusion products into directed motion. The particles are then collected on electrodes at various large electrical potentials. This method has demonstrated an experimental efficiency of 48

353:, denoted σ, measures the probability that a fusion reaction will happen. This depends on the relative velocity of the two nuclei. Higher relative velocities generally increase the probability, but the probability begins to decrease again at very high energies. 3228:'s design and R&D work on DEMO, and EUROfusion confirmed it was proceeding with its Roadmap to Fusion Energy, beginning the conceptual design of DEMO in partnership with the European fusion community, suggesting an EU-backed machine had entered the race. 1824: 3171:

Then, in October 2023 the UK government, in enacting the Energy Act 2023, made the UK the first country to legislate for fusion separately from fission, to support planning and investment, including the UK's planned prototype fusion power plant for 2040;

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In 2024, both South Korea and Japan announced major initiatives to accelerate their national fusion strategies, by building electricity-generating public-private fusion plants in the 2030s, aiming to begin operations in the 2040s and 2030s respectively.

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inventory in the wall and dust could build up to many kilograms, representing a waste of resources and a radiological hazard in case of an accident. Graphite found favor as material for short-lived experiments, but appears unlikely to become the primary

3273:) exists abundantly in the ocean: about 1 in 6500 hydrogen atoms in seawater is deuterium. Although this is only about 0.015%, seawater is plentiful and easy to access, implying that fusion could supply the world's energy needs for millions of years. 2345:

Assuming complete removal of tritium and He recycling, only 6% of the fusion energy is carried by neutrons. The tritium-suppressed D-D fusion requires an energy confinement that is 10 times longer compared to D-T and double the plasma temperature.

2817:

radioactive for about 50 years, with other low-level waste being radioactive for another 100 years or so thereafter. The fusion waste's short half-life eliminates the challenge of long-term storage. By 500 years, the material would have the same

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Park, Jaeyoung; Krall, Nicholas A.; Sieck, Paul E.; Offermann, Dustin T.; Skillicorn, Michael; Sanchez, Andrew; Davis, Kevin; Alderson, Eric; Lapenta, Giovanni (June 1, 2014). "High Energy Electron Confinement in a Magnetic Cusp Configuration".

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of the reactor housing and potentially allowing more efficient energy harvesting (via any of several pathways). In practice, D-D side reactions produce a significant number of neutrons, leaving p-B as the preferred cycle for aneutronic fusion.

1100:: Similar to a field-reversed configuration, a semi-stable plasma structure made by using the plasmas' self-generated magnetic field. A spheromak has both toroidal and poloidal fields, while a field-reversed configuration has no toroidal field. 5229:

D. A. Sutherland, T. R. Jarboe et al., "The dynomak: An advanced spheromak reactor concept with imposed-dynamo current drive and next-generation nuclear power technologies", Fusion Engineering and Design, Volume 89, Issue 4, April 2014, pp.

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Ion Beams: Ion beams replace laser beams to heat the fuel. The main difference is that the beam has momentum due to mass, whereas lasers do not. As of 2019 it appears unlikely that ion beams can be sufficiently focused spatially and in

2812:, the neutron flux turns the structural materials radioactive. The amount of radioactive material at shut-down may be comparable to that of a fission reactor, with important differences. The half-lives of fusion and neutron activation 588:

considers the energy balance between the energy produced in fusion reactions to the energy being lost to the environment. In order to generate usable energy, a system would have to produce more energy than it loses. Lawson assumed an

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Engineering assurance for fusion materials—providing irradiated sample data and modelled predictions such that plant designers, operators and regulators have confidence that materials are suitable for use in future commercial power

165:), and increased safety. However, the necessary combination of temperature, pressure, and duration has proven to be difficult to produce in a practical and economical manner. A second issue that affects common reactions is managing 1278:

An electric field heats ions to fusion conditions. The machine typically uses two spherical cages, a cathode inside the anode, inside a vacuum. These machines are not considered a viable approach to net power because of their high

3416:. Tuck had been involved in the Manhattan project, but had switched to working on fusion in the early 1950s. He applied for funding for the project as part of a White House sponsored contest to develop a fusion reactor along with 3314:). The higher temperatures and lower reaction rates thus significantly complicate the engineering challenges. In any case, other drawbacks remain, for instance reactors requiring only deuterium fueling will have greatly enhanced 12036:. Laboratorium voor Plasmafysica – Laboratoire de Physique des Plasmas Koninklijke Militaire School – École Royale Militaire; Laboratorium voor Natuurkunde, Universiteit Gent. pp. Section III.B. and Table VI. Archived from 2752:

In practice, magnets usually have safety devices to stop or limit the current when a quench is detected. If a large magnet undergoes a quench, the inert vapor formed by the evaporating cryogenic fluid can present a significant

3435:, which used deuterium to pass a current around the outside of its cylinder to create a magnetic force in the center. After the success of Scylla I, Los Alamos went on to build multiple pinch machines over the next few years. 309:—the diameter of a proton or neutron. The fuel atoms must be supplied enough kinetic energy to approach one another closely enough for the strong force to overcome the electrostatic repulsion in order to initiate fusion. The " 8632:

Gonzalez de Vicente, Sehila M.; Smith, Nicholas A.; El-Guebaly, Laila; Ciattaglia, Sergio; Di Pace, Luigi; Gilbert, Mark; Mandoki, Robert; Rosanvallon, Sandrine; Someya, Youji; Tobita, Kenji; Torcy, David (August 1, 2022).

130:, to allow them to reach the Lawson criterion requirements with less extreme conditions. Most designs aim to heat their fuel to around 100 million kelvins, which presents a major challenge in producing a successful design. 12131:. Washington, DC; Springfield, Va.: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program; [For sale by the National Technical Information Service [distributor. 10410: 2688:

In laser-driven inertial containment the larger size of the reaction chamber reduces the stress on materials. Although failure of the reaction chamber is possible, stopping fuel delivery prevents catastrophic failure.

2342:

neutron spectrum. The disadvantage of D-D compared to D-T is that the energy confinement time (at a given pressure) must be 30 times longer and the power produced (at a given pressure and volume) is 68 times less.

1028:, with an internal current. When completed, ITER will become the world's largest tokamak. As of September 2018 an estimated 226 experimental tokamaks were either planned, decommissioned or operating (50) worldwide. 3231:

In October 2023, the UK-oriented Agile Nations group announced a fusion working group. One month later, the UK and the US announced a bilateral partnership to accelerate fusion energy. Then, in December 2023 at

3048:

Scenarios developed in the 2000s and early 2010s discussed the effects of the commercialization of fusion power on the future of human civilization. Using nuclear fission as a guide, these saw ITER and later

1705:

pass charged helium atoms at several megavolts and just coming off the fusion reaction through a tube with a coil of wire around the outside. This passing charge at high voltage pulls electricity through the

1078:. A series of mirror machines were built by the US government in the 1970s and 1980s, principally at LLNL. However, calculations in the 1970s estimated it was unlikely these would ever be commercially useful. 11934: 3007:

The size of the investments and time lines meant that fusion research was traditionally almost exclusively publicly funded. However, starting in the 2010s, the promise of commercializing a paradigm-changing

2946:

proliferation resistance might only be possible at an early phase of research and development. The theoretical and computational tools needed for hydrogen bomb design are closely related to those needed for

3045:. In 2021, Commonwealth Fusion Systems (CFS) obtained $ 1.8 billion in scale-up funding, and Helion Energy obtained a half-billion dollars with an additional $ 1.7 billion contingent on meeting milestones. 3003:

has allocated $ US367M–$ US671M every year since 2010, peaking in 2020, with plans to reduce investment to $ US425M in its FY2021 Budget Request. About a quarter of this budget is directed to support ITER.

3874:, successfully operated for 102 seconds in a high-containment mode (H-mode) containing high ion temperatures of more than 100 million degrees in plasma tests conducted from December 2023 to February 2024. 3614:

with a much smaller radius. It used a single large conductor in the center, with magnets as half-rings off of this conductor. The aspect ratio fell to as low as 1.2. Peng's advocacy caught the interest of

2449:, reported a new fusion rate record for proton-boron fusion, with an estimated 80 million fusion reactions during a 1.5 nanosecond laser fire, 100 times greater than reported in previous experiments. 4325:"Scientists Achieve Nuclear Fusion Breakthrough With Blast of 192 Lasers – The advancement by Lawrence Livermore National Laboratory researchers will be built on to further develop fusion energy research" 1668:

Neutron blankets: These neutrons can regenerate spent fission fuel. Tritium can be produced using a breeder blanket of liquid lithium or a helium cooled pebble bed made of lithium-bearing ceramic pebbles.

3204:

FPP. On 24 September 2020, the United States House of Representatives approved a research and commercialization program. The Fusion Energy Research section incorporated a milestone-based, cost-sharing,

1575:: a loop of wire is inserted into the magnetic field. As the field passes through the loop, a current is made. The current measures the total magnetic flux through that loop. This has been used on the 11081: 2227:, but does not consume the neutron. Neutron multiplication reactions are required to replace the neutrons lost to absorption by other elements. Leading candidate neutron multiplication materials are 13336:

Jürgen; Banduch, Martin; Barbui, Tullio; Beidler, Craig; Benndorf, Andree; Beurskens, Marc; Biel, Wolfgang; Birus, Dietrich; Blackwell, Boyd; Blanco, Emilio; Blatzheim, Marko; et al. (2016).

1755:: The loss of material must be sufficiently slow. The plasma carries energy off with it, so rapid loss of material will disrupt fusion. Material can be lost by transport into different regions or 599: 11596: 10601:

Nicholas, T. E. G.; Davis, T. P.; Federici, F.; Leland, J. E.; Patel, B. S.; Vincent, C.; Ward, S. H. (February 2021). "Re-examining the Role of Nuclear Fusion in a Renewables-Based Energy Mix".

3813:

TAE Technologies announced results for its Norman device, holding a temperature of about 60 MK for 30 milliseconds, 8 and 10 times higher, respectively, than the company's previous devices.

11110: 3870:, Japan. The reactor is a joint project between Japan and the European Union. The reactor had achieved its first plasma in October 2023. Subsequently, South Korea's fusion reactor project, the 1822: 1617:. In ICF systems, firing a second beam into a gold foil adjacent to the target makes x-rays that traverse the plasma. In tokamaks, this can be done using mirrors and detectors to reflect light. 2433:

Because the confinement properties of the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the

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Scenarios since 2010 note computing and material science advances enabling multi-phase national or cost-sharing "Fusion Pilot Plants" (FPPs) along various technology pathways, such as the UK

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In April 2022, First Light announced that their hypersonic projectile fusion prototype had produced neutrons compatible with fusion. Their technique electromagnetically fires projectiles at

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Kessel, C. E.; Blanchard, J. P.; Davis, A.; El-Guebaly, L.; Ghoniem, N.; Humrickhouse, P. W.; Malang, S.; Merrill, B. J.; Morley, N. B.; Neilson, G. H.; Rensink, M. E. (September 1, 2015).

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tungsten not be too hot (a few tens of eV rather than hundreds of eV). Tungsten also has issues around eddy currents and melting in off-normal events, as well as some radiological issues.

8490: 1184:: This combines a laser pulse with a magnetic pinch. The pinch community refers to it as magnetized liner inertial fusion while the ICF community refers to it as magneto-inertial fusion. 1174:

Fast ignition: This method uses two laser blasts. The first blast compresses the fusion fuel, while the second ignites it. As of 2019 this technique had lost favor for energy production.

6784:. Innovative Nuclear Energy Systems for Sustainable Development of the World. Proceedings of the Second COE-INES International Symposium, INES-2, November 26–30, 2006, Yokohama, Japan. 2967:

150 billion years. To put this in context, 150 billion years is close to 30 times the remaining lifespan of the Sun, and more than 10 times the estimated age of the universe.

1900:

or produced by other nuclear reactions. Ultimately, researchers hope to adopt the protium–boron-11 reaction, because it does not directly produce neutrons, although side reactions can.

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Lerner, Eric J.; Murali, S. Krupakar; Shannon, Derek; Blake, Aaron M.; Van Roessel, Fred (March 23, 2012). "Fusion reactions from >150 keV ions in a dense plasma focus plasmoid".

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is the name for the resultant bare nucleus. The result of this ionization is plasma, which is a heated cloud of ions and free electrons that were formerly bound to them. Plasmas are

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in its nucleus, it requires the least effort to attain fusion, and yields the most net energy output. Also since it has one electron, hydrogen is the easiest fuel to fully ionize.

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Taccetti, J. M.; Intrator, T. P.; Wurden, G. A.; Zhang, S. Y.; Aragonez, R.; Assmus, P. N.; Bass, C. M.; Carey, C.; deVries, S. A.; Fienup, W. J.; Furno, I. (September 25, 2003).

3760:(REBCO) superconducting tapes to produce high-magnetic field coils that it claimed could produce comparable magnetic field strength in a smaller configuration than other designs. 1194:: Sends an electric current through thin tungsten wires, heating them sufficiently to generate x-rays. Like the indirect drive approach, these x-rays then compress a fuel capsule. 829: 921:

surrounding the reactor core. When struck by a high-energy neutron, the blanket heats up. It is then actively cooled with a working fluid that drives a turbine to produce power.

294:, requiring an input of energy. The heavy nuclei bigger than iron have many more protons resulting in a greater repulsive force. For nuclei lighter than iron-56, the reaction is 208:(NIF) laser in the United States. Researchers are also studying other designs that may offer less expensive approaches. Among these alternatives, there is increasing interest in 12098: 2988: 10418: 2511:

wire for fusion reactors. This new wire was shown to conduct between 700 and 2000 Amps per square millimeter. The company was able to produce 186 miles of wire in nine months.

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began operation. NIF achieved net energy gain in 2013, as defined in the very limited sense as the hot spot at the core of the collapsed target, rather than the whole target.

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Labik, George; Brown, Tom; Johnson, Dave; Pomphrey, Neil; Stratton, Brentley; Viola, Michael; Zarnstorff, Michael; Duco, Mike; Edwards, John; Cole, Mike; Lazarus, Ed (2007).

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beams. Direct drive can in principle be efficient, but insufficient uniformity has prevented success. Indirect drive uses beams to heat a shell, driving the shell to radiate

1330:

Fusion has been initiated by man, using uncontrolled fission explosions to stimulate fusion. Early proposals for fusion power included using bombs to initiate reactions. See

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Key, M.H. (1985). "Highlights of laser fusion related research by United Kingdom universities using the SERC Central Laser Facility at the Rutherford Appleton Laboratory".

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inductive voltage spikes and arcing. Permanent damage to the magnet is rare, but components can be damaged by localized heating, high voltages, or large mechanical forces.

2502:

SuperOx was able to produce over 186 miles of YBCO wire in nine months for use in fusion reactor magnets, dramatically surpassing the company's previous production targets.

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reaction, release much more of their energy in the form of charged particles. In these cases, power extraction systems based on the movement of these charges are possible.

873:

fusion): Q = ∞ (brown), Q = 10 (red), Q = 2 (yellow), Q = 1 (green), Q = 0.1 (strong blue), Q = 0.01 (lighter blue), Q = 0.001 (even lighter blue), Q = 0.0001 (faint blue).

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Wurzel, Samuel E., and Scott C. Hsu. "Progress toward fusion energy breakeven and gain as measured against the Lawson criterion." arXiv preprint arXiv:2105.10954 (2021).

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Menard, J. E.; Bromberg, L.; Brown, T.; Burgess, T.; Dix, D.; El-Guebaly, L.; Gerrity, T.; Goldston, R. J.; Hawryluk, R. J.; Kastner, R.; Kessel, C. (October 1, 2011).

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commercial energy and promote R&D between countries, as well as rationalize fusion regulation. Later the same year, the US partnered with the IAEA to launch the

7554:

Emerging nuclear energy systems 1989: proceedings of the Fifth International Conference on Emerging Nuclear Energy Systems, Karlsruhe, F.R. Germany, July 3–6, 1989

5258:

Nuckolls, John; Wood, Lowell; Thiessen, Albert; Zimmerman, George (1972). "Laser Compression of Matter to Super-High Densities: Thermonuclear (CTR) Applications".

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Delivering 2.05 megajoules (MJ) of light energy to the target, resulting in 3.15 MJ of fusion energy output from appr. 400 MJ electric energy to drive the lasers.

3061:, within the 2030–2040 time frame. Notably, in June 2021, General Fusion announced it would accept the UK government's offer to host the world's first substantial 5457: 3722:

Private and public research accelerated in the 2010s. General Fusion developed plasma injector technology and Tri Alpha Energy tested its C-2U device. The French

12345:

Kusama, Y. (2002), Stott, Peter E.; Wootton, Alan; Gorini, Giuseppe; Sindoni, Elio (eds.), "Requirements for Diagnostics in Controlling Advanced Tokamak Modes",

378: 317:

required to move the fuel atoms near enough. Atoms can be heated to extremely high temperatures or accelerated in a particle accelerator to produce this energy.

134:

is extremely rare on earth, having a half life of only ~12.3 years. Consequently, during the operation of envisioned fusion reactors, known as breeder reactors,

98:

provides extremely long confinement times that reach the conditions needed for fusion energy production. Proposed fusion reactors generally use heavy hydrogen

947:(LLNL) in the 1980s as a method to maintain a voltage directly using fusion reaction products. This has demonstrated energy capture efficiency of 48 percent. 17135: 6300:

McGuire, Thomas. Heating Plasma for Fusion Power Using Magnetic Field Oscillations. Baker Botts LLP, assignee. Issued: 4/2/14, Patent 14/243,447. N.d. Print.

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Hsu, S. C.; Awe, T. J.; Brockington, S.; Case, A.; Cassibry, J. T.; Kagan, G.; Messer, S. J.; Stanic, M.; Tang, X.; Welch, D. R.; Witherspoon, F. D. (2012).

3824:

On November 8, in an invited talk to the 63rd Annual Meeting of the APS Division of Plasma Physics, the National Ignition Facility claimed to have triggered

3431:

passes a current down the center of a plasma, which makes a magnetic force around the outside which squeezes the plasma to fusion conditions. Scylla I was a

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energy output from the capsule. A researcher from Imperial College London stated that the majority of the field agreed that ignition had been demonstrated.

3718:

Example of a stellarator design: A coil system (blue) surrounds plasma (yellow). A magnetic field line is highlighted in green on the yellow plasma surface.

3641:

In 1997, JET produced a peak of 16.1 MW of fusion power (65% of heat to plasma), with fusion power of over 10 MW sustained for over 0.5 sec.

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of 12.32 years, it is hard to find, store, produce, and is expensive. Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from

1763:

To produce self-sustaining fusion, part of the energy released by the reaction must be used to heat new reactants and maintain the conditions for fusion.

1514:. Reconnection helps fusion because it instantly dumps energy into a plasma, heating it quickly. Up to 45% of the magnetic field energy can heat the ions. 1094:: This device traps plasma in a self-organized quasi-stable structure; where the particle motion makes an internal magnetic field which then traps itself. 932:. In these systems, the power output is enhanced by the fission events, and power is extracted using systems like those in conventional fission reactors. 16662: 16353: 15400: 11444:"The place of peace in the ITER machine assembly launch: Thematic analysis of the political speeches in the world's largest science diplomacy experiment" 2458: 2413:. Their fusion releases no neutrons, but produces energetic charged alpha (helium) particles whose energy can directly be converted to electrical power: 1116:: Here the plasma moves inside a ring. It has an internal magnetic field. Moving out from the center of this ring, the magnetic field reverses direction. 10440: 3638:

In 1996, Tore Supra created a plasma for two minutes with a current of almost 1 million amperes, totaling 280 MJ of injected and extracted energy.

2609:

retention through co-deposition and implantation is essential in fusion contexts, as it helps to minimize the accumulation of this radioactive isotope.

1040:: Twisted rings of hot plasma. The stellarator attempts to create a natural twisted plasma path, using external magnets. Stellarators were developed by 372:. In this case, it is useful to use the average particle cross section over the velocity distribution. This is entered into the volumetric fusion rate: 16957: 14288:

Cohen, Sam, and B. Berlinger. "Long-pulse Operation of the PFRC-2 Device." The Joint US-Japan Compact Torus. Wisconsin, Madison. 22 Aug. 2016. Lecture.

7164:

Hedditch, John; Bowden-Reid, Richard; Khachan, Joe (October 2015). "Fusion in a magnetically-shielded-grid inertial electrostatic confinement device".

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Menard, J. E.; Brown, T.; El-Guebaly, L.; Boyer, M.; Canik, J.; Colling, B.; Raman, R.; Wang, Z.; Zhai, Y.; Buxton, P.; Covele, B. (October 1, 2016).

4930:

Proceedings of the second United Nations International Conference on the Peaceful Uses of Atomic Energy held in Geneva 1 September – 13 September 1958

1784:. Because the mirror machines were straight, they had some advantages over ring-shaped designs. The mirrors were easier to construct and maintain and 14348: 3249: 13864: 10204: 6536:

Esarey, Eric; Ride, Sally K.; Sprangle, Phillip (September 1, 1993). "Nonlinear Thomson scattering of intense laser pulses from beams and plasmas".

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Fusion power promises to provide more energy for a given weight of fuel than any fuel-consuming energy source currently in use. The fuel (primarily

1595:

against the surrounding plasma. The metal collects charged particles, drawing a current. As the voltage changes, the current changes. This makes an

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Ono, Y.; Tanabe, H.; Yamada, T.; Gi, K.; Watanabe, T.; Ii, T.; Gryaznevich, M.; Scannell, R.; Conway, N.; Crowley, B.; Michael, C. (May 1, 2015).

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Koller, Markus T.; Davis, James W.; Goodland, Megan E.; Abrams, Tyler; Gonderman, Sean; Herdrich, Georg; Frieß, Martin; Zuber, Christian (2019).

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from 48 of 65 nuclear sites in the US). In any case the reserve and start-up tritium inventory requirements are likely to be unacceptably large.

2925:

Small-scale fusion station: As a result of much higher power consumption, heat dissipation and a more recognizable design compared to enrichment

2219:

The reactant neutron is supplied by the D-T fusion reaction shown above, and the one that has the greatest energy yield. The reaction with Li is

1808:, especially the field-reversed configuration and the spheromak, attempt to combine the advantages of toroidal magnetic surfaces with those of a 8497: 305:

The repulsive electrostatic interaction between nuclei operates across larger distances than the strong force, which has a range of roughly one

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materials are also low-activation, are strong and light, and are promising for laser-inertial reactors where a magnetic field is not required.

1633:

Visible, IR, UV, and X-rays are emitted anytime a particle changes velocity. If the reason is deflection by a magnetic field, the radiation is

1416:

Many approaches, equipment, and mechanisms are employed across multiple projects to address fusion heating, measurement, and power production.

1250:, together with physicists Brian Nelson and Uri Shumlak, co-founded Zap Energy to attempt to commercialize the technology for power production. 6236:

Yamada, M.; Chen, L.-J.; Yoo, J.; Wang, S.; Fox, W.; Jara-Almonte, J.; Ji, H.; Daughton, W.; Le, A.; Burch, J.; Giles, B. (December 6, 2018).

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Even on smaller production scales, the containment apparatus is blasted with matter and energy. Designs for plasma containment must consider:

16642: 15437: 14242: 13845: 12126: 9017:

Glaser, A.; Goldston, R. J. (2012). "Proliferation risks of magnetic fusion energy: Clandestine production, covert production and breakout".

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Developments from late 2020 onwards have led to talk of a "new space race" with multiple entrants, pitting the US against China and the UK's

3139:

consulted with private fusion companies to consider a national pilot plant. The following month, the United States Department of Energy, the

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In contrast, inertial confinement systems approach useful triple product values via higher density, and have short confinement intervals. In

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Molodyk, A., et al. "Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion."

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tritium. Tritium may leak from reactors. Some estimates suggest that this would represent a substantial environmental radioactivity release.

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Spitzer continued his stellarator research at Princeton. While fusion did not immediately transpire, the effort led to the creation of the

2304:

Fusing two deuterium nuclei is the second easiest fusion reaction. The reaction has two branches that occur with nearly equal probability:

11767: 3668:(EAST) test reactor was completed. It was the first tokamak to use superconducting magnets to generate both toroidal and poloidal fields. 3424:. However, it turned out that the neutrons they had detected were from beam-target interactions, not fusion, and they withdrew the claim. 15874: 3221:, recommending a market-driven, cost-sharing plant for 2035–2040, and the launch of the Congressional Bipartisan Fusion Caucus followed. 13455:"Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X" 12055: 4404: 1524:

injected into a mass of fusion fuel can induce thermonuclear reactions. This possibility as a method of spacecraft propulsion, known as

1148:

light. These x-rays heat a fuel pellet, causing it to collapse inward to compress the fuel. The largest system using this method is the

16730: 12127:

Schulze, Norman R.; United States; National Aeronautics and Space Administration; Scientific and Technical Information Program (1991).

6847:

Hanaor, D. A. H.; Kolb, M. H. H.; Gan, Y.; Kamlah, M.; Knitter, R. (2014). "Solution based synthesis of mixed-phase materials in the Li

5721:

US patent 5,160,695, Robert W. Bussard, "Method and apparatus for creating and controlling nuclear fusion reactions", issued 1992-11-03

3408:

at Los Alamos National Laboratory called Scylla I at the start of 1958. The team that achieved it was led by a British scientist named

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megajoules of energy—more than was delivered to the target—NIF's 192 lasers consumed 322 MJ of grid energy in the conversion process.

17233: 13703: 13042: 12030: 11203: 9090: 1731:

Confinement refers to all the conditions necessary to keep a plasma dense and hot long enough to undergo fusion. General principles:

17472: 13952: 11491:"Potential contribution of fusion power generation to low-carbon development under the Paris Agreement and associated uncertainties" 11395:"Towards Fusion Energy in the Industry 5.0 and Society 5.0 Context: Call for a Global Commission for Urgent Action on Fusion Energy" 9904:"Socioeconomic and environmental impacts of bringing the sun to earth: A sustainability analysis of a fusion power plant deployment" 7971:

Neu, R.; et al. (2005). "Tungsten: an option for divertor and main chamber plasma facing components in future fusion devices".

1727:

devices as of the mid-1990s. The regime allowing thermonuclear ignition with high gain lies near the upper right corner of the plot.

1517:

Magnetic oscillations: varying electric currents can be supplied to magnetic coils that heat plasma confined within a magnetic wall.

332:

and magnetically controlled because the charges are separated. This is used by several fusion devices to confine the hot particles.

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Magnetic mirrors suffered from end losses, requiring high power, complex magnetic designs, such as the baseball coil pictured here.

886:

that energy stays within the volume. This is known as the "triple product": the plasma density, temperature, and confinement time.

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National Academies of Sciences, Engineering, and Medicine (U.S.). Committee on a Strategic Plan for U.S. Burning Plasma Research.

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is 2500 times lower than for D-T, although per unit mass of fuel, this is still considerably higher compared to fission reactors.

2235:, but the Li reaction helps to keep the neutron population high. Natural lithium is mainly Li, which has a low tritium production 17683: 17523: 17462: 15758: 15697: 10735: 3201: 3173: 3058: 2485:

Structural materials able to retain their strength under neutron bombardment at high operating temperatures (over 550 degrees C);

2025:

of hydrogen and is commonly available. The large mass ratio of the hydrogen isotopes makes their separation easy compared to the

1576: 17603: 12156:. Progress in Astronautics and Aeronautics. American Institute of Aeronautics and Astronautics. January 1, 1995. pp. 1–46. 10871: 9395: 5239:

Jarboe, T. R., et al. "Spheromak formation by steady inductive helicity injection." Physical Review Letters 97.11 (2006): 115003

17428: 16056: 16016: 15371: 14790: 13118: 11793: 8534: 5838:"5 Big ideas for fusion power: Startups, universities, and major companies are vying to commercialize a nuclear fusion reactor" 4379: 4089: 3764: 3551: 3245: 2828:

The choice of materials is less constrained than in conventional fission, where many materials are required for their specific

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energy capture was easier to implement. Poor confinement has led this approach to be abandoned, except in the polywell design.

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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

6708:

Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character

3135:

As fusion pilot plants move within reach, legal and regulatory issues must be addressed. In September 2020, the United States

2469: 1605:: "Light scatters" from plasma can be used to reconstruct plasma behavior, including density and temperature. It is common in 675:{\displaystyle P_{\text{out}}=\eta _{\text{capture}}\left(P_{\text{fusion}}-P_{\text{conduction}}-P_{\text{radiation}}\right)} 16657: 15432: 13634: 12223:"Physics and technology considerations for the deuterium-tritium fuel cycle and conditions for tritium fuel self sufficiency" 9122: 8125:"Plasma–surface interaction in the stellarator W7-X: Conclusions drawn from operation with graphite plasma-facing components" 3093: 13563: 12011: 11668: 10082:"Assessment on Tokamak Fusion Power Plant to Contribute to Global Climate Stabilization in the Framework of Paris Agreement" 2673:

additional fuel is necessary to continue the reaction. This large fuel supply is what offers the possibility of a meltdown.

2507:

devices. In 2021, SuperOx, a Russian and Japanese company, developed a new manufacturing process for making superconducting

1831:

The Electra Laser at Naval Research Laboratory demonstrates 90,000 shots in 10 hours, repetition needed for IFE power plant.

17479: 13655:"Development and large volume production of extremely high current density YBa 2 Cu 3 O 7 superconducting wires for fusion" 9066:

Strong Neutron Sources – How to cope with weapon material production capabilities of fusion and spallation neutron sources?

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for sustainable energy research, putting research into fusion power well ahead of that of any single rival technology. The

1493: 10178: 9292: 7961:"Thermal response of nanostructured tungsten". Shin Kajita, et al., January 2014, Nuclear Fusion 54 (2014) 033005 (10 pp.) 4642: 2866:, but it can be produced in other ways. The energetic neutrons from a fusion reactor could be used to breed weapons-grade 985:

can generate its own internal magnetic field. This can reject an externally applied magnetic field, making it diamagnetic.

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Neu, R.; et al. (2016). "Advanced tungsten materials for plasma-facing components of DEMO and fusion power plants".

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In some scenarios, fusion power technology could be adapted to produce materials for military purposes. A huge amount of

2825:. Nonetheless, classification as intermediate level waste rather than low-level waste may complicate safety discussions. 1167:

facilities. Good implosions require fuel pellets with close to a perfect shape in order to generate a symmetrical inward

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Y-K Martin Peng, "Spherical Torus, Compact Fusion at Low Yield". Oak Ridge National Laboratory/FEDC-87/7 (December 1984)

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Ishiyama, Shintaro; Muto, Yasushi; Kato, Yasuyoshi; Nishio, Satoshi; Hayashi, Takumi; Nomoto, Yasunobu (March 1, 2008).

1840:, which then implode the pellet. The beams are commonly laser beams, but ion and electron beams have been investigated. 1445: 860:

the mass of the ions. Fusion power systems must operate in a region where the rate of fusion is higher than the losses.

18094: 17678: 15161: 14679: 14660: 14641: 14623: 14568: 14509: 14488: 14469: 12987: 12942: 12899: 12866: 12720: 12529: 12362: 12321: 12169: 11341: 11153: 10138: 9490: 9440: 9320: 8817:

Nicholas, T. E. G.; Davis, T. P.; Federici, F.; Leland, J.; Patel, B. S.; Vincent, C.; Ward, S. H. (February 1, 2021).

8701: 8635:"Overview on the management of radioactive waste from fusion facilities: ITER, demonstration machines and power plants" 8605: 8577: 8462: 8428: 8365: 7852: 7693: 7337: 7312: 7287: 7015: 6752: 6678: 6653: 6415: 6365: 6108: 6075: 5904: 5429: 5310: 5206: 5173: 5048: 4773: 4279: 3860: 3148: 3000: 1848: 1596: 1465: 1404: 1266: 369: 213: 14405: 3076: 2661:

Accident potential and effect on the environment are critical to social acceptance of nuclear fusion, also known as a

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Self-organizing plasma conducts electric and magnetic fields. Its motions generate fields that can in turn contain it.

261:. Iron-56 has the highest, making it the most stable. Nuclei to the left are likely to release energy when they fuse ( 18389: 16758: 16637: 14838: 12823: 12575: 12192: 11618: 8765: 4324: 2482:

Magnets and insulators that are resistant to irradiation from fusion reactions—especially under cryogenic conditions;

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Compounds that can be used within the power plant to optimise breeding of tritium fuel to sustain the fusion process;

86:

in which fusion can occur. The combination of these figures that results in a power-producing system is known as the

14366: 13538: 11031: 7040: 3241:, to collaboratively crowdsource ideas to accelerate commercial fusion energy, in line with the US COP28 statement. 2280:, the vacuum vessel was sufficiently radioactive that it required remote handling for the year following the tests. 1654:

Neutron blankets absorb neutrons, which heats the blanket. Power can be extracted from the blanket in various ways:

1024:: the most well-developed and well-funded approach. This method drives hot plasma around in a magnetically confined 504: 17988: 17853: 16388: 15692: 15118: 14217: 8388: 7878:"Hydrogen permeation barriers: Basic requirements, materials selection, deposition methods, and quality evaluation" 4883:"An Eulerian MHD model for the analysis of magnetic flux compression by expanding diamagnetic fusion plasma sphere" 4172: 3620: 2272:

expected in a commercial D-T fusion reactor is about 100 times that of fission power reactors, posing problems for

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the conductors would remove energy faster than fusion reactions could replace it. Modern variations, including the

7119:"Stable, thermal equilibrium, large-amplitude, spherical plasma oscillations in electrostatic confinement devices" 5465: 2620:) have been proposed, e.g., by injection of 1–5 mm thick streams flowing at 10 m/s on solid substrates. 1378:

can cause fusion. As of 2007 producing muons required more energy than can be obtained from muon-catalyzed fusion.

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Gardner, Timothy (June 1, 2023). "US announces $ 46 million in funds to eight nuclear fusion companies". Reuters.

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Barr, W. L.; Moir, R. W.; Hamilton, G. W. (1982). "Experimental results from a beam direct converter at 100 kV".

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The Novette target chamber (metal sphere with diagnostic devices protruding radially), which was reused from the

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Fusion researchers have investigated various confinement concepts. The early emphasis was on three main systems:

12744:

Jarvis, O. N. (June 16, 2006). "Neutron measurements from the preliminary tritium experiment at JET (invited)".

9572: 9001: 3420:. The previous year, 1957, the British had claimed that they had achieved thermonuclear fusion reactions on the 1881: 1624: 1159:

Direct drive: Lasers directly heat the fuel pellet. Notable direct drive experiments have been conducted at the

18374: 18220: 17921: 17770: 17228: 15748: 14091: 7076: 6329: 6238:"The two-fluid dynamics and energetics of the asymmetric magnetic reconnection in laboratory and space plasmas" 3757: 3111:

levelized cost of energy estimates are substantially lower. For instance, the 2019 levelized cost of energy of

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Senatore, C.; Bonura, M.; Pantoja, A. E.; Wimbush, S. C.; Strickland, N. M.; Vasiliev, A. (January 22, 2021).

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19 at a caged fuel pellet. The deuterium fuel is compressed at Mach 204, reaching pressure levels of 100 TPa.

18467: 18354: 17695: 17528: 16952: 16880: 15687: 15595: 14763: 13826: 12664:"High β produced by neutral beam injection in the START (Small Tight Aspect Ratio Tokamak) spherical tokamak" 3654: 3140: 1529: 1085: 17: 14430: 14115: 7646: 5392:. Proceedings of 2011 Particle Accelerator Conference. New York, New York, USA. p. 1386. Archived from 3427:

Scylla I was a classified machine at the time, so the achievement was hidden from the public. A traditional

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could be produced by a fusion power station; tritium is used in the trigger of hydrogen bombs and in modern

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More rarely a magnet defect can cause a quench. When this happens, that particular spot is subject to rapid

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Depending on the approach, these effects may be higher or lower than fission reactors. One estimate put the

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radiation at high speeds. If the reason is deflection by another particle, plasma radiates X-rays, known as

720: 18038: 17775: 17484: 17238: 16735: 16175: 16114: 15022: 13259: 11530:

Nicholas, T. E. G.; Davis, T. P.; Federici, F.; Leland, J.; Patel, B. S.; Vincent, C.; Ward, S. H. (2021).

10654: 7219:"A biased probe analysis of potential well formation in an electron only, low beta Polywell magnetic field" 6493:

Mott-Smith, H. M.; Langmuir, Irving (September 1, 1926). "The Theory of Collectors in Gaseous Discharges".

5511: 3136: 2832:. Fusion reactors can be designed using "low activation", materials that do not easily become radioactive. 1909: 1691: 1091: 778: 6778:"Study of steam, helium and supercritical CO2 turbine power generations in prototype fusion power reactor" 807: 18494: 18188: 18101: 18073: 18030: 17995: 17833: 17660: 17598: 17423: 17327: 17213: 16681: 16381: 16129: 16051: 16021: 15361: 15354: 15241: 15146: 15133: 15014: 10162: 9886: 9291:

DOE/CF-0167 – Department of Energy FY 2021 Congressional Budget Request, Budget in Brief, February 2020.

8014:

Philipps, V.; et al. (2011). "Tungsten as material for plasma-facing components in fusion devices".

6704:"IX. A dynamical theory of the electric and luminiferous medium. Part III. relations with material media" 4928:

Post, R. F. (1958). United Nations International Conference on the Peaceful Uses of Atomic Energy (ed.).

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experiments using lasers began as early as 1965. Several laser systems were built at LLNL, including the

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The UK claimed that it had gotten fusion first in 1957 on ZETA, but this claim had to later be withdrawn.

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80% of the resultant energy is carried off by neutrons, which limits the use of direct energy conversion.

1739: 1606: 1425: 1324:(piston compression with liquid metal liner), HyperJet Fusion (plasma jet compression with plasma liner). 1126: 1015: 960: 590: 193: 10167:. Washington, DC: American Physical Society Division of Plasma Physics Community Planning Process. 2020. 7628: 5698: 2017:

This reaction is common in research, industrial and military applications, usually as a neutron source.

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Srivastava, Krishna M.; Vyas, D. N. (1982). "Non-linear analysis of the stability of the Screw Pinch".

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Proceedings of the second United Nations International Conference on the Peaceful Uses of Atomic Energy

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developed the concept of the tokamak, combining a low-power pinch device with a low-power stellarator.

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represents an investment of over twenty billion dollars, and possibly tens of billions more, including

2285: 1382: 1149: 905: 749: 551: 469: 205: 14758: 13244: 9903: 8939:"Conceptual Design of Low Activation Target Chamber and Components for the National Ignition Facility" 8818: 8244: 8204: 8165: 3080:

Levelized cost of energy (LCOE) for various sources of energy including wind, solar and nuclear energy

2421:

Side reactions are likely to yield neutrons that carry only about 0.1% of the power, which means that

18276: 18176: 17858: 17467: 17250: 16109: 15958: 15272: 14876: 13979: 13922: 11935:"Gov't to chase 'artificial sun' with $ 866 million investment in nuclear fusion reactor development" 10982:"NRC Hosts Virtual Public Meeting on Developing Options for a Regulatory Framework for Fusion Energy" 8693:

Principles of Fusion Energy: An Introduction to Fusion Energy for Students of Science and Engineering

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Jarboe, T. R., et al. "Recent results from the HIT-SI experiment." Nuclear Fusion 51.6 (2011): 063029

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seawater would be very costly and might require more energy than the energy that would be generated.

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Magnetic loops bend the field lines back on themselves, either in circles or more commonly in nested

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Obenschain, Stephen; et al. (2015). "High-energy krypton fluoride lasers for inertial fusion".

13279: 10023: 9692: 9148: 8963: 7440:"Impact of tritium removal and He-3 recycling on structure damage parameters in a D–D fusion system" 5393: 4685: 2605:

allowing it to withstand intense conditions without rapid degradation. Additionally, tungsten's low

1221:, was the last major experiment of the sort. The problems in z-pinch led to the tokamak design. The 691: 18425: 18420: 18291: 18106: 17948: 17848: 17760: 16969: 16855: 16815: 16627: 16026: 15928: 15634: 15123: 13980:"There is no "breakthrough": NIF fusion power still consumes 130 times more energy than it creates" 13749: 12813: 11251: 9756:"Economic aspects of the deployment of fusion energy: the valley of death and the innovation cycle" 6588: 6396:"National Compact Stellarator Experiment Vacuum Vessel External Flux Loops Design and Installation" 5028: 4497: 4274: 3702:

The preamplifiers of the National Ignition Facility. In 2012, the NIF achieved a 500-terawatt shot.

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In magnetic confinement, the density is low, on the order of a "good vacuum". For instance, in the

357: 209: 14246: 14142:"Breaking New Ground: JET Tokamak's Latest Fusion Energy Record Shows Mastery of Fusion Processes" 13754:. 63rd Annual Meeting of the APS Division of Plasma Physics, November 8–12, 2021; Pittsburgh, PA. 12383: