View source for Physics:History of nuclear fusion

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The '''history of nuclear fusion''' began early in the 20th century as an inquiry into how stars powered themselves and expanded to incorporate a broad inquiry into the nature of matter and energy, as potential applications expanded to include warfare, energy production and rocket propulsion.
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== Early research ==
[[File:Chart of Fusion Approaches.png|thumb|400px|Various authors
have also put forth ways to organize all the fusion approaches that have been tested over the past 70+ years. This flow chart above groups the approaches into color coded families, these are: the Pinch Family (orange), The 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 Fusion (PJMIF, dark pink).]]
In 1920 British physicist [[Biography:Francis William Aston|Francis William Aston]] discovered that the mass equivalent of four [[Physics:Hydrogen atom|hydrogen atom]]s is heavier than the mass of one [[Physics:Helium atom|helium atom]] ([[Physics:Helium-4|He-4]]), which implied that net energy can be released by combining hydrogen atoms to form helium. This provided the first hints of a mechanism by which stars could produce energy. Throughout the 1920s, Arthur Stanley Eddington became a major proponent of the [[Astronomy:Proton–proton chain reaction|proton–proton chain reaction]] (PP reaction) as the primary system running the [[Astronomy:Sun|Sun]].<ref name=":14">{{Cite book|last=Clery|first=Daniel|url=https://www.worldcat.org/oclc/1128270426|title=A piece of the sun : the quest for fusion energy|date=July 29, 2014|isbn=978-1-4683-1041-2|location=New York|oclc=1128270426}}</ref><ref>{{cite journal|last1=Eddington|first1=A. S.|date=October 1920|title=The internal constitution of the stars|url=http://articles.adsabs.harvard.edu/full/1920Obs....43..341E|journal=The Observatory|volume=43|pages=341–358|bibcode=1920Obs....43..341E|access-date=20 July 2015}}</ref> Quantum tunneling was discovered by [[Biography:Friedrich Hund|Friedrich Hund]] in 1929, and shortly afterwards Robert Atkinson and [[Biography:Fritz Houtermans|Fritz Houtermans]] used the measured masses of light elements to show that large amounts of energy could be released by fusing small nuclei.

Henry Norris Russell observed that the relationship in the [[Hertzsprung–Russell diagram]] suggested that a star's heat came from a hot core rather than from the entire star. Eddington used this to calculate that the core would have to be about 40&nbsp;million K. This became a matter of debate because the value is much higher than astronomical observations that suggested about one-third to one-half that value. [[Biography:George Gamow|George Gamow]] introduced the mathematical basis for [[Physics:Quantum tunnelling|quantum tunnelling]] in 1928.<ref>{{cite book|last1=Nimtz|first1=G.|title=Compendium of Quantum Physics|last2=Clegg|first2=B.|date=12 August 2009|publisher=Springer|isbn=978-3-540-70622-9|editor-last1=Greenberger|editor-first1=D.|pages=799–802|editor-last2=Hentschel|editor-first2=K.|editor-last3=Weinert|editor-first3=F.}}</ref> In 1929 Atkinson and [[Biography:Fritz Houtermans|Houtermans]] provided the first estimates of the stellar fusion rate. They showed that fusion can occur at lower energies than previously believed, backing Eddington's calculations.<ref>{{cite journal|last1=Atkinson|first1=R. d E.|last2=Houtermans|first2=F. G.|date=1929|title=Zur Frage der Aufbaumöglichkeit der Elemente in Sternen|journal=Zeitschrift für Physik|volume=54|issue=9–10|pages=656–665|bibcode=1929ZPhy...54..656A|doi=10.1007/BF01341595|s2cid=123658609}}</ref>

Nuclear experiments began using a [[Physics:Particle accelerator|particle accelerator]] built by [[Biography:John Cockcroft|John Cockcroft]] and [[Biography:Ernest Walton|Ernest Walton]] at [[Biography:Ernest Rutherford|Ernest Rutherford]]s' [[Organization:Cavendish Laboratory|Cavendish Laboratory]] at [[Organization:University of Cambridge|University of Cambridge]]. In 1932, Walton produced the first man-made fission by using [[Physics:Proton|proton]]s from the accelerator to split [[Chemistry:Lithium|lithium]] into [[Physics:Alpha particle|alpha particle]]s.<ref name="invent">{{cite web|last=Arnoux|first=Robert|date=May 2014|title=Who "invented" fusion?|url=https://www.iter.org/mag/3/29|access-date=2021-06-11|website=ITER|language=en}}</ref> The accelerator was then used to fire ''[[Physics:Deuteron|deuteron]]s'' at various targets. Working with Rutherford and others, [[Biography:Mark Oliphant|Mark Oliphant]] discovered the nuclei of [[Physics:Helium-3|Helium-3]] (''helions'') and [[Physics:Tritium|tritium]] (''tritons''), the first case of human-caused fusion.{{sfn|Cockburn|Ellyard|1981|pp=52–55}}<ref>{{cite journal|last1=Oliphant|first1=M. L. E.|last2=Rutherford|first2=Lord|date=3 July 1933|title=Experiments on the Transmutation of Elements by Protons|journal=Proceedings of the Royal Society A|volume=141|issue=843|pages=259–281|bibcode=1933RSPSA.141..259O|doi=10.1098/rspa.1933.0117|doi-access=free}}</ref><ref>{{cite journal|last1=Oliphant|first1=M. L. E.|last2=Kinsey|first2=B. B.|last3=Rutherford|first3=Lord|author-link3=Lord Rutherford|date=1 September 1933|title=The Transmutation of Lithium by Protons and by Ions of the Heavy Isotope of Hydrogen|journal=Proceedings of the Royal Society A|volume=141|issue=845|pages=722–733|bibcode=1933RSPSA.141..722O|doi=10.1098/rspa.1933.0150|doi-access=free}}</ref><ref>{{cite journal|last1=Oliphant|first1=M. L. E.|last2=Harteck|first2=P.|author-link2=Paul Harteck|last3=Rutherford|first3=Lord|author-link3=Lord Rutherford|date=1 May 1934|title=Transmutation Effects Observed with Heavy Hydrogen|journal=Proceedings of the Royal Society A|volume=144|issue=853|pages=692–703|bibcode=1934RSPSA.144..692O|doi=10.1098/rspa.1934.0077|doi-access=free}}</ref><ref>{{Cite web|title=Mark Oliphant - Engineering and Technology History Wiki|url=http://ethw.org/Mark_Oliphant|access-date=2021-06-11|website=ethw.org|date=4 February 2016 }}</ref>

Neutrons from fusion were first detected in 1933.{{sfn|Cockburn|Ellyard|1981|p={{page needed|date=May 2020}}}} <!--The Arnoux source claims that the experiment was in 1934.-->The experiment involved the acceleration of protons towards a target{{sfn|Cockburn|Ellyard|1981|pp=48–50}} at energies of up to 600,000 electron volts.

A theory verified by [[Biography:Hans Bethe|Hans Bethe]] in 1939 showed that [[Physics:Beta decay|beta decay]] and quantum tunneling in the [[Astronomy:Solar core|Sun's core]] might convert one of the protons into a [[Physics:Neutron|neutron]] and thereby produce [[Physics:Deuterium|deuterium]] rather than a [[Physics:Isotopes of helium|diproton]]. The deuterium would then fuse through other reactions to further increase the energy output. For this work, Bethe won the 1967 Nobel Prize in Physics.<ref name=":14" /><ref>{{cite web|title=The Nobel Prize in Physics 1967 Hans Bethe|url=https://www.nobelprize.org/prizes/physics/1967/bethe/facts/|website=Nobel Prize}}</ref><ref>{{cite web|title=Hans Bethe|url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1967/bethe-bio.html|access-date=11 March 2016|website=Hans Bethe - Biographical|publisher=Nobel Prize.org}}</ref>

In 1938, [[Biography:Peter Thonemann (physicist)|Peter Thonemann]] developed a detailed plan for a [[Physics:Pinch (plasma physics)|pinch]] device, but was told to do other work for his thesis.{{sfn|Dean|2013|p=3}}

The first patent related to a fusion reactor was registered in 1946<ref>{{cite web|title=British Patent 817681|url=http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=GB817681&F=0|access-date=2013-06-22|publisher=V3.espacenet.com}}</ref> by the United Kingdom Atomic Energy Authority. The inventors were [[Biography:George Paget Thomson|Sir George Paget Thomson]] and Moses Blackman. This was the first detailed examination of the [[Physics:Z-pinch|Z-pinch]] concept. Starting in 1947, two UK teams carried out experiments based on this concept.<ref name=":14" />

== 1950s ==
[[File:IvyMike2.jpg|thumb|The first man-made device to achieve ignition was the detonation of this fusion device, codenamed Ivy Mike.]]
[[File:Kink_instability_at_Aldermaston.jpg|right|thumb|Early photo of plasma inside a pinch machine (Imperial College 1950/1951)]]
The first successful man-made fusion device was the [[Physics:Boosted fission weapon|boosted fission weapon]] tested in 1951 in the Greenhouse Item test. The first true fusion weapon was 1952's Ivy Mike, and the first practical example was 1954's Castle Bravo. In these devices, the energy released by a fission explosion compresses and heats the fuel, starting a fusion reaction. Fusion releases [[Physics:Neutron|neutron]]s. These neutrons hit the surrounding fission fuel, causing the atoms to split apart much faster than normal fission processes. This increased the effectiveness of bombs: normal fission weapons blow themselves apart before all their fuel is used; fusion/fission weapons do not waste their fuel.

=== Stellarator ===
In 1949 expatriate German Ronald Richter proposed the [[Physics:Huemul Project|Huemul Project]] in Argentina, announcing positive results in 1951. These turned out to be fake, but prompted others' interest. [[Biography:Lyman Spitzer|Lyman Spitzer]] began considering ways to solve problems involved in confining a hot plasma, and, unaware of the z-pinch efforts, he created the stellarator. Spitzer applied to the US Atomic Energy Commission for funding to build a test device.

During this period, [[Biography:James L. Tuck|James L. Tuck]], who had worked with the UK teams on z-pinch, had been introducing the stellarator concept to his coworkers at LANL. When he heard of Spitzer's pitch, he applied to build a pinch machine of his own, the [[Physics:Perhapsatron|Perhapsatron]].<ref name=":14" /><ref>...the first money to be allocated [to controlled nuclear research] happened to be for Tuck, and was diverted from Project Lincoln, in the Hood Laboratory. The coincidence of names prompted the well-known cover name "Project Sherwood". James L. Tuck, [http://bayesrules.net/JamesTuckVitaeAndBiography.pdf "Curriculum Vita and Autobiography"], declassified document from Los Alamos National Laboratory (1974), reproduced with permission. [https://web.archive.org/web/20120209082757/http://bayesrules.net/JamesTuckVitaeAndBiography.pdf Archived] 9 February 2012.</ref>

Spitzer's idea won funding and he began work under Project Matterhorn. His work led to the creation of [[Organization:Princeton Plasma Physics Laboratory|Princeton Plasma Physics Laboratory]] (PPPL). Tuck returned to LANL and arranged local funding to build his machine. By this time it was clear that the pinch machines were afflicted by instability, stalling progress. In 1953, Tuck and others suggested solutions that led to a second series of pinch machines, such as the [[Physics:ZETA (fusion reactor)|ZETA]] and [[Physics:Sceptre (fusion reactor)|Sceptre]] devices.<ref name=":14" />

Spitzer's first machine, 'A' worked, but his next one, 'B', suffered from instabilities and plasma leakage.<ref>{{Cite journal|last=Stix|first=T. H.|date=1998|title=Highlights in early stellarator research at Princeton|url=http://inis.iaea.org/Search/search.aspx?orig_q=RN:30002355|journal=Helical System Research|language=en}}</ref><ref>{{Cite tech report|last=Johnson|first=John L.|date=2001-11-16|title=The Evolution of Stellarator Theory at Princeton|url=https://www.osti.gov/biblio/792587-fxKdXU/native/|language=en|doi=10.2172/792587|osti=792587}}</ref>

In 1954 AEC chair Lewis Strauss foresaw electricity as "[[Physics:Too cheap to meter|too cheap to meter]]".<ref name="thisdayinquotes">{{cite web|year=2009|title=This Day in Quotes: September 16 – Too cheap to meter: the great nuclear quote debate|url=http://www.thisdayinquotes.com/2009/09/too-cheap-to-meter-nuclear-quote-debate.html|access-date=2009-09-16|publisher=This day in quotes}}</ref> Strauss was likely referring to fusion power,<ref>Pfau, Richard (1984) ''No Sacrifice Too Great: The Life of Lewis L. Strauss'' University Press of Virginia, Charlottesville, Virginia, p. 187. {{ISBN|978-0-8139-1038-3}}</ref> part of the secret [[Physics:Project Sherwood|Project Sherwood]]—but his statement was interpreted as referring to fission. The AEC had issued more realistic testimony regarding fission to Congress months before, projecting that "costs can be brought down... [to]... about the same as the cost of electricity from conventional sources..."<ref>{{cite book|author=David Bodansky|url=https://books.google.com/books?id=qBqbr8uV9c8C&q=strauss+son+cheap+meter&pg=PA32|title=''Nuclear Energy: Principles, Practices, and Prospects''|publisher=Springer|year=2004|isbn=978-0-387-20778-0|page=32|access-date=2008-01-31}}</ref>

=== Edward Teller ===
In 1951 [[Biography:Edward Teller|Edward Teller]] and [[Biography:Stanislaw Ulam|Stanislaw Ulam]] at [[Organization:Los Alamos National Laboratory|Los Alamos National Laboratory]] (LANL) developed the Teller-Ulam design for a [[Engineering:Thermonuclear weapon|thermonuclear weapon]], allowing for the development of multi-megaton yield fusion bombs. Fusion work in the UK was classified after the [[Biography:Klaus Fuchs|Klaus Fuchs]] affair.

In the mid-1950s the theoretical tools used to calculate the performance of fusion machines were not predicting their actual behavior. Machines invariably leaked plasma at rates far higher than predicted. In 1954, [[Biography:Edward Teller|Edward Teller]] gathered fusion researchers at the Princeton Gun Club. He pointed out the problems and suggested that any system that confined plasma within concave fields was doomed due to what became known as [[Physics:Interchange instability|interchange instability]]. Attendees remember him saying in effect that the fields were like rubber bands, and they would attempt to snap back to a straight configuration whenever the power was increased, ejecting the plasma. He suggested that the only way to predictably confine plasma would be to use convex fields: a "cusp" configuration.<ref name=":19">{{Cite book|url=https://www.worldcat.org/oclc/696150063|title=Edward Teller Centennial Symposium : modern physics and the scientific legacy of Edward Teller : Livermore, CA, USA, 28 May 2008|date=2010|publisher=World Scientific|author1=Libby, Stephen B. |author2=Van Bibber, Karl A. |others=Edward Teller Centennial Symposium (2008 : Livermore, Calif.)|isbn=978-981-283-800-1|location=Hackensack, NJ|oclc=696150063}}</ref><sup>:118</sup>

When the meeting concluded, most researchers turned out papers explaining why Teller's concerns did not apply to their devices. Pinch machines did not use magnetic fields in this way, while the mirror and stellarator claques proposed various solutions. This was soon followed by [[Biography:Martin David Kruskal|Martin David Kruskal]] and [[Biography:Martin Schwarzschild|Martin Schwarzschild]]'s paper discussing pinch machines, however, which demonstrated those devices' instabilities were inherent.<ref name=":19" /><sup>:118</sup>

=== ZETA ===
The largest "classic" pinch device was the [[Physics:ZETA (fusion reactor)|ZETA]], which started operation in the UK in 1957. Its name is a take-off on [[Physics:Research reactor|small experimental fission reactors]] that often had "zero energy" in their name, such as [[Physics:ZEEP|ZEEP]].

In early 1958, [[Biography:John Cockcroft|John Cockcroft]] announced that fusion had been achieved in the ZETA, an announcement that made headlines around the world. He dismissed US physicists' concerns. US experiments soon produced similar neutrons, although temperature measurements suggested these could not be from fusion. The ZETA neutrons were later demonstrated to be from different versions of the instability processes that had plagued earlier machines. Cockcroft was forced to retract his fusion claims, tainting the entire field for years. ZETA ended in 1968.<ref name=":14" />

=== Scylla ===
The first experiment to achieve controlled [[Physics:Thermonuclear fusion|thermonuclear fusion]] was accomplished using Scylla I at LANL in 1958.<ref name="Phillips, James 2013">{{cite journal|last=Phillips|first=James|date=1983|title=Magnetic Fusion|url=https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-83-5080|url-status=dead|journal=Los Alamos Science|pages=64–67|archive-url=https://web.archive.org/web/20161223163131/http://permalink.lanl.gov/object/tr?what=info%3Alanl-repo%2Flareport%2FLA-UR-83-5080|archive-date=December 23, 2016|access-date=4 Apr 2013}}</ref><ref>[https://fas.org/sgp/othergov/doe/lanl/lib-www/la-pubs/00403632.pdf Reviewing next the thermonuclear plasma achievements at Los Alamos, we have achieved:(1) The first controlled thermonuclear reaction.], Review of Controlled Thermonuclear Research at Los Alamos 1965, J. L. Tuck</ref><ref>[https://fas.org/sgp/othergov/doe/lanl/pubs/00285870.pdf The first experiment in which thermonuclear fusion was achieved in any laboratory was done in 1958 with the Scylla I machine. ], Winter/Spring 1983 Los Alamos Science.</ref> Scylla I was a θ-pinch machine, with a cylinder full of deuterium. Electric current shot down the sides of the cylinder. The current made magnetic fields that [[Physics:Pinch (plasma physics)|pinched]] the plasma, raising temperatures to 15&nbsp;million degrees Celsius, for long enough that atoms fused and produced neutrons.<ref name="Seife, Charles 2008">{{cite book|last=Seife|first=Charles|title=Sun in a bottle : the strange history of fusion and the science of wishful thinking|publisher=Viking|year=2008|isbn=978-0-670-02033-1|location=New York|oclc=213765956}}</ref><ref name="Phillips, James 2013" /> The Sherwood program sponsored a series of Scylla machines at Los Alamos. The program began with 5 researchers and $100,000 in US funding in January 1952.<ref>{{cite report|url=https://fas.org/sgp/othergov/doe/lanl/lib-www/la-pubs/00403632.pdf|title=A Review of Los Alamos Fusion Research|author=E. L. Kemp|section=Personnel and Financial history of the Los Alamos Sherwood Program|year=1965}}</ref> By 1965, a total of $21&nbsp;million had been spent.{{Citation needed|date=October 2020}} The [[Physics:Pinch (plasma physics)#The θ-pinch|θ-pinch]] approach was abandoned after calculations showed it could not scale up to produce a reactor.

=== Tokamak ===
In 1950–1951 in the [[Place:Soviet Union|Soviet Union]], [[Biography:Igor Tamm|Igor Tamm]] and [[Biography:Andrei Sakharov|Andrei Sakharov]] first discussed a [[Physics:Tokamak|tokamak]]-like approach. Experimental research on those designs began in 1956 at the [[Place:Moscow|Moscow]] [[Organization:Kurchatov Institute|Kurchatov Institute]] by a group of Soviet scientists led by [[Biography:Lev Artsimovich|Lev Artsimovich]]. The tokamak essentially combined a low-power pinch device with a low-power stellarator. The notion was to combine the fields in such a way that the particles orbited within the reactor a particular number of times, today known as the "[[Physics:Safety factor (plasma physics)|safety factor]]". The combination of these fields dramatically improved confinement times and densities, resulting in huge improvements over existing devices.<ref name=":14" />

=== Other ===
[[File:IvyMike2.jpg|right|thumb|Ivy Mike, the first thermonuclear weapon, in 1952]]
In 1951 Ivy Mike, part of Operation Ivy, became the first detonation of a [[Engineering:Thermonuclear weapon|thermonuclear weapon]], yielding 10.4 megatons of TNT using liquid deuterium. Cousins and Ware built a toroidal pinch device in England and demonstrated that the plasma in pinch devices is inherently unstable. In 1953 The Soviet Union tested its RDS-6S test, (codenamed "Joe 4" in the US) demonstrated a fission/fusion/fission ("Layercake") design that yielded 600 kilotons. [[Biography:Igor Kurchatov|Igor Kurchatov]] spoke at Harwell on pinch devices,<ref>[http://www.efda.org/2010/04/lecture-of-i-v-kurchatov-at-harwell/ "Lecture of I.V. Kurchatov at Harwell"], from the address of I.V. Kurchatov: "On the possibility of producing thermonuclear reactions in a gas discharge" at Harwell on 25 April 1956. [https://web.archive.org/web/20150720180242/https://www.euro-fusion.org/2010/04/lecture-of-i-v-kurchatov-at-harwell/ Archived] 20 July 2015.</ref> revealing that the USSR was working on fusion.

Seeking to generate electricity, {{wipe|Japan}}, {{wipe|France}} and Sweden all start fusion research programs

In 1955, [[Biography:John D. Lawson (scientist)|John D. Lawson (scientist)]] creates what is now known as the [[Physics:Lawson criterion|Lawson criterion]] which is a criteria for a fusion reactor to produce more energy than is lost to the environment due to problems like [[Physics:Bremsstrahlung|Bremsstrahlung]] radiation.

In 1956 the Soviet Union began publishing articles on plasma physics, leading the US and UK to follow over the next several years.

The [[Physics:Sceptre (fusion reactor)|Sceptre III]] z-pinch plasma column remained stable for 300 to 400 microseconds, a dramatic improvement on previous efforts. The team calculated that the plasma had an electrical resistivity around 100 times that of copper, and was able to carry 200 kA of current for 500 microseconds.

== 1960s ==
In 1960 [[Biography:John Nuckolls|John Nuckolls]] published the concept of [[Physics:Inertial confinement fusion|inertial confinement fusion]] (ICF). The [[Physics:Laser|laser]], introduced the same year, turned out to be a suitable "driver".

In 1961 the [[Place:Soviet Union|Soviet Union]] tested its 50&nbsp;megaton Tsar Bomba, the most powerful thermonuclear weapon ever.

Spitzer published a key plasma physics text at Princeton in 1963.<ref>{{Cite book|last=Spitzer|first=L|url=https://www.worldcat.org/oclc/768663704|title=Physics of fully ionized gases|date=1962|publisher=Interscience Publishers|location=New York, NY|language=en|oclc=768663704}}</ref> He took the [[Physics:Ideal gas law|ideal gas law]]s and adapted them to an ionized plasma, developing many of the fundamental equations used to model a plasma.

Laser fusion was suggested in 1962 by scientists at LLNL. Initially, lasers had little power. Laser fusion (inertial confinement fusion) research began as early as 1965.

At the 1964 World's Fair, the public was given its first fusion demonstration.<ref>{{Cite web|title=1964 New York World's Fair 1965 - Attractions - General Electric - Page Eight|url=http://www.nywf64.com/genele08.shtml|url-status=dead|archive-url=https://web.archive.org/web/20141030210437/http://www.nywf64.com/genele08.shtml|archive-date=October 30, 2014|website=www.nywf64.com}}</ref> The device was a Theta-pinch from General Electric. This was similar to the Scylla machine developed earlier at Los Alamos.

By the mid-1960s progress had stalled across the world. All of the major designs were losing plasma at unsustainable rates. The 12-beam "4 pi laser" attempt at inertial confinement fusion developed at LLNL targeted a gas-filled target chamber of about 20 centimeters in diameter.

The [[Physics:Magnetic mirror|magnetic mirror]] was first published in 1967 by [[Biography:Richard F. Post|Richard F. Post]] and many others at LLNL.<ref>{{Cite book|last1=Post|first1=R|url=https://www.worldcat.org/oclc/4434498138|title=Mirror Systems: Fuel Cycles, Loss Reduction, and Energy Recovery|date=1969|location= |language=en|oclc=4434498138}}</ref> The mirror consisted of two large magnets arranged so they had strong fields within them, and a weaker, but connected, field between them. Plasma introduced in the area between the two magnets would "bounce back" from the stronger fields in the middle.

[[Biography:Andrei Sakharov|A.D. Sakharov]]'s group constructed the first tokamaks. The most successful were the T-3 and its larger version T-4. T-4 was tested in 1968 in Novosibirsk, producing the first quasistationary fusion reaction.<ref>{{Cite book|last=Irvine|first=Maxwell|url=https://www.worldcat.org/oclc/920881367|title=Nuclear power: a very short introduction|date=2014|publisher=Oxford University Press|isbn=978-0-19-958497-0|location=Oxford|language=en|oclc=920881367}}</ref><sup>:90</sup> When this was announced, the international community was skeptical. A British team was invited to see T-3, and confirmed the Soviet claims. A burst of activity followed as many planned devices were abandoned and tokamaks were introduced in their place—the C model stellarator, then under construction after many redesigns, was quickly converted to the Symmetrical Tokamak.<ref name=":14" />

In his work with vacuum tubes, [[Biography:Philo Farnsworth|Philo Farnsworth]] observed that electric charge accumulated in the tube. In 1962, Farnsworth patented a design using a positive inner cage to concentrate plasma and fuse protons.<ref>US Patent 3,258,402 June 28, 1966</ref> During this time, Robert L. Hirsch joined Farnsworth Television labs and began work on what became the Farnsworth-Hirsch Fusor. This effect became known as the [[Physics:Multipactor effect|Multipactor effect]].<ref>{{Cite journal|last=Cartlidge|first=Edwin|date=2007|title=The secret world of amateur fusion|url=https://www.worldcat.org/oclc/5886288632|journal=Physics World|volume=20|issue=3|pages=10–11|doi=10.1088/2058-7058/20/3/18|issn=0953-8585|oclc=5886288632}}</ref> Hirsch patented the design in 1966<ref>US Patent 3,386,883 June 4, 1968</ref> and published it in 1967.<ref>{{Cite journal|last=Hirsch|first=Robert L|date=1967|title=Inertial‐Electrostatic Confinement of Ionized Fusion Gases|url=https://www.worldcat.org/oclc/5540048930|journal=Journal of Applied Physics|language=en|volume=38|issue=11|pages=4522–4534|bibcode=1967JAP....38.4522H|doi=10.1063/1.1709162|issn=0021-8979|oclc=5540048930}}</ref>

Plasma temperatures of approximately 40 million degrees Celsius and 10<sup>9</sup> deuteron-deuteron fusion reactions per discharge were achieved at [[Organization:Los Alamos National Laboratory|LANL]] with Scylla IV.<ref>[https://fas.org/sgp/othergov/doe/lanl/pubs/00285870.pdf In 1964 plasma temperatures of approximately 40 million degrees...were achieved with the Scylla IV], Winter/Spring 1983 LOS ALAMOS SCIENCE.</ref>

In 1968 the Soviets announced results from the T-3 [[Physics:Tokamak|tokamak]], claiming temperatures an order of magnitude higher than any other device. A UK team, nicknamed "The Culham Five", confirmed the results. The results led many other teams, including the Princeton group, which converted their stellarator to a tokamak.

== 1970s ==
{{multiple image
| total_width = 440
| image1 = Shiva amplifier chains.jpg
| caption1 = Shiva laser, 1977, the largest ICF laser system built in the seventies
| image2 = The Tandem Mirror Experiment.jpg
| caption2 = The Tandem Mirror Experiment (TMX) in 1979
}}
Princeton's conversion of the [[Physics:Model C stellarator|Model C stellarator]] to a tokamak produced results matching the Soviets. With an apparent solution to the magnetic bottle problem in-hand, plans begin for a larger machine to test scaling and methods to heat the plasma.

In 1972, [[Biography:John Nuckolls|John Nuckolls]] outlined the idea of [[Physics:Fusion ignition|fusion ignition]],<ref name="Nuckolls, John 1972">{{cite journal|last1=Nuckolls|first1=John|last2=Wood|first2=Lowell|last3=Thiessen|first3=Albert|last4=Zimmerman|first4=George|year=1972|title=Laser Compression of Matter to Super-High Densities: Thermonuclear (CTR) Applications|journal=Nature|volume=239|issue=5368|pages=139–142|bibcode=1972Natur.239..139N|doi=10.1038/239139a0|s2cid=45684425}}</ref> a fusion chain reaction. Hot helium made during fusion reheats the fuel and starts more reactions. Nuckolls's paper started a major development effort. LLNL built laser systems including [[Engineering:Argus laser|Argus]], [[Engineering:Cyclops laser|Cyclops]], [[Engineering:Janus laser|Janus]], the neodymium-[[Physics:Doping (semiconductor)|doped]] glass (Nd:glass) laser [[Engineering:Long path laser|Long Path]], [[Engineering:Shiva laser|Shiva laser]], and the 10 beam [[Engineering:Nova (laser)|Nova]] in 1984. Nova would ultimately produce 120 kilojoules of infrared light during a nanosecond pulse.

The UK built the Central Laser Facility in 1976.<ref>{{cite journal|last1=Key|first1=M.H.|year=1985|title=Highlights of laser fusion related research by United Kingdom universities using the SERC Central Laser Facility at the Rutherford Appleton Laboratory|journal=Nuclear Fusion|volume=25|issue=9|pages=1351–1353|doi=10.1088/0029-5515/25/9/063|s2cid=119922168 }}</ref>

The "advanced tokamak" concept emerged, which included non-circular plasma, internal diverters and limiters, superconducting magnets, and operation in the so-called "H-mode" island of increased stability.<ref>{{Citation|last=Kusama|first=Y.|title=Requirements for Diagnostics in Controlling Advanced Tokamak Modes|date=2002|url=https://doi.org/10.1007/978-1-4419-8696-2_5|work=Advanced Diagnostics for Magnetic and Inertial Fusion|pages=31–38|editor-last=Stott|editor-first=Peter E.|place=Boston, MA|publisher=Springer US|language=en|doi=10.1007/978-1-4419-8696-2_5|isbn=978-1-4419-8696-2|access-date=2020-10-12|editor2-last=Wootton|editor2-first=Alan|editor3-last=Gorini|editor3-first=Giuseppe|editor4-last=Sindoni|editor4-first=Elio}}</ref> Two other designs became prominent; the compact tokamak sited the magnets on the inside of the vacuum chamber,<ref>{{Cite journal|last=Menard|first=J. E.|date=2019-02-04|title=Compact steady-state tokamak performance dependence on magnet and core physics limits|url=|journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences|volume=377|issue=2141|pages=20170440|bibcode=2019RSPTA.37770440M|doi=10.1098/rsta.2017.0440|issn=1364-503X|pmc=6365855|pmid=30967044}}</ref><ref>{{Cite journal|last=Kaw|first=P.K|date=1999|title=Steady state operation of tokamaks|url=http://dx.doi.org/10.1088/0029-5515/39/11/411|journal=Nuclear Fusion|volume=39|issue=11|pages=1605–1607|doi=10.1088/0029-5515/39/11/411|s2cid=250826481 |issn=0029-5515}}</ref> and the [[Physics:Spherical tokamak|spherical tokamak]] with as small a cross section as possible.<ref>{{Cite book|date=2011-11-01|title=An indispensable truth: how fusion power can save the planet}}</ref><ref>{{Cite journal|last=Miley|first=George H.|date=1995|title=Compact Tori as Extensions of the Spherical Tokamak|url=http://dx.doi.org/10.13182/fst95-a11947111|journal=Fusion Technology|volume=27|issue=3T|pages=382–386|doi=10.13182/fst95-a11947111|bibcode=1995FuTec..27..382M |issn=0748-1896}}</ref>

In 1974 J.B. Taylor re-visited ZETA and noticed that after an experimental run ended, the plasma entered a short period of stability. This led to the [[Physics:Reversed field pinch|reversed field pinch]] concept. On May 1, 1974, the KMS fusion company (founded by [[Biography:Kip Siegel|Kip Siegel]]) achieved the world's first laser induced fusion in a deuterium-tritium pellet.{{sfn|Clery|2014|p={{page needed|date=May 2020}}}}
[[File:IFE_laser_parameter_space.jpg|right|thumb|300x300px|Progress in power and energy levels attainable by inertial confinement lasers has increased dramatically since the early 1970s.]]
The Princeton Large Torus (PLT), the follow-on to the Symmetrical Tokamak, surpassed the best Soviet machines and set temperature records that were above what was needed for a commercial reactor. Soon after it received funding with the target of breakeven.

In the mid-1970s, [[Physics:Project PACER|Project PACER]], carried out at LANL explored the possibility of exploding small hydrogen bombs (fusion bombs) inside an underground cavity.<ref>{{Cite journal|last=Long|first=F. A.|date=1976-10-01|title=Peaceful nuclear explosions|url=https://doi.org/10.1080/00963402.1976.11455642|journal=Bulletin of the Atomic Scientists|volume=32|issue=8|pages=18–28|bibcode=1976BuAtS..32h..18L|doi=10.1080/00963402.1976.11455642|issn=0096-3402}}</ref><sup>:25</sup> As an energy source, the system was the only system that could work using the technology of the time. It required a large, continuous supply of nuclear bombs, however, with questionable economics.

In 1976, the two beam [[Engineering:Argus laser|Argus laser]] became operational at LLNL.<ref name=":16">{{Cite web|date=2004-11-09|title=Empowering Light--Historic Accomplishments in Laser Research: 50 Years of Science|url=http://www.llnl.gov/50science/lasers.html|archive-url=https://web.archive.org/web/20041109063036/http://www.llnl.gov/50science/lasers.html|archive-date=November 9, 2004|access-date=2020-10-10}}</ref> In 1977, the 20 beam [[Engineering:Shiva laser|Shiva laser]] there was completed, capable of delivering 10.2 kilojoules of infrared energy on target. At a price of $25&nbsp;million and a size approaching that of a football field, Shiva was the first megalaser.<ref name=":16" />

At a 1977 workshop at the Claremont Hotel in Berkeley Dr. C. Martin Stickley, then Director of the Energy Research and Development Agency ’s Office of Inertial Fusion, claimed that "no showstoppers" lay on the road to fusion energy.

The DOE selected a Princeton design [[Physics:Tokamak Fusion Test Reactor|Tokamak Fusion Test Reactor]] (TFTR) and the challenge of running on deuterium-tritium fuel.

The 20 beam Shiva laser at LLNL became capable of delivering 10.2 kilojoules of infrared energy on target. Costing $25 million and nearly covering a football field, Shiva was the first "megalaser" at LLNL.

== 1980s ==
[[File:TMX_Baseball_Coils.jpg|thumb|Magnetic mirrors suffered from end losses, requiring high power, complex magnetic designs, such as the baseball coil pictured here.]]<!--| image2 = WP:NFCC violation: The Mirror Fusion Test Facility During Construction.jpg--> <!--| caption2 = The magnetic mirror test facility during construction }}--> 
{{multiple image
| image1 = Novette laser.jpg
| caption1 = The Novette target chamber (metal sphere with diagnostic devices protruding radially), which was reused from the Shiva project and two newly built laser chains visible in background.
| image2 = Fusion target implosion on NOVA laser.jpg
| width1 = 200
| caption2 = Inertial confinement fusion implosion on the Nova laser during the 1980s was a key driver of fusion development.
}}
In the German/US HIBALL study,<ref>...Gesellschaft für Schwerionenforschung; Institut für Plasmaphysik, Garching; Kernforschungszentrum Karlsruhe, University of Wisconsin, Madison; Max-Planck-Institut für Quantenoptik</ref> Garching used the high repetition rate of the RF driver to serve four reactor chambers using liquid lithium inside the chamber cavity. In 1982 [[Physics:High-confinement mode|high-confinement mode]] (H-mode) was discovered in tokamaks.

=== Magnetic mirror ===
The US funded a [[Physics:Magnetic mirror|magnetic mirror]] program in the late 1970s and early 1980s. This program resulted in a series of magnetic mirror devices including: 2X,<ref>{{Cite book|last1=Krall|first1=N. A|url=https://www.worldcat.org/oclc/560090579|title=Principles of plasma physics. Krall.|last2=Trivelpiece|first2=A. W.|date=1973|publisher=McGraw-Hill|location=New York|language=en|oclc=560090579}}</ref><sup>:273</sup> Baseball I, Baseball II, the [[Physics:Tandem Mirror Experiment|Tandem Mirror Experiment]] and upgrade, the [[Organization:Mirror Fusion Test Facility|Mirror Fusion Test Facility]], and MFTF-B. These machines were built and tested at LLNL from the late 1960s to the mid-1980s.<ref>{{Cite book|last1=Lawrence Livermore National Laboratory|url=https://www.osti.gov/servlets/purl/5759138|title=Summary of results from the Tandem Mirror Experiment|editor1-first=T.C|editor1-last=Simonen|date=1981|publisher=Lawrence Livermore National Laboratory; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy|location=Livermore, Calif; Oak Ridge, Tenn.|doi=10.2172/5759138|language=en|oclc=727190637}}</ref><ref>{{Cite book|last=Coensgen|first=F.H.|title=TMX Major Project Proposal|publisher=Lawrence Livermore National Laboratory|year=1977|location=Livermore, CA}}</ref> The final machine, MFTF cost 372&nbsp;million dollars and was, at that time, the most expensive project in LLNL history.<ref name="Booth">{{cite journal|last=Booth|first=William|date=9 Oct 1987|title=Fusion's $372-Million Mothball|journal=Science|volume=238|issue=4824|pages=152–155|bibcode=1987Sci...238..152B|doi=10.1126/science.238.4824.152|pmid=17800453}}</ref> It opened on February 21, 1986, and immediately closed, allegedly to balance the federal budget.<ref>{{cite news|last=Koppel|first=Niko|date=May 20, 2010|title=Edwin E. Kintner, Nuclear Power Pioneer, Dies at 90|newspaper=NYTimes.com|url=https://www.nytimes.com/2010/05/21/science/21kintner.html|access-date=2014-08-24}}</ref>

=== Laser ===
Laser fusion progress: in 1983, the NOVETTE laser was completed. The following December, the ten-beam NOVA laser was finished. Five years later, NOVA produced 120 kilojoules of infrared light during a nanosecond pulse.<ref>{{Cite book|last1=Lawrence Livermore National Laboratory|url=http://www.osti.gov/servlets/purl/16710-UOC0xx/native/|title=Laser Programs, the first 25 years, 1972-1997.|date=1998|publisher=Lawrence Livermore National Laboratory; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy|location=Livermore, Calif; Oak Ridge, Tenn.|doi=10.2172/16710|language=en|oclc=68365115}}</ref>

Research focused on either fast delivery or beam smoothness. Both focused on increasing energy uniformity. One early problem was that the light in the [[Physics:Infrared|infrared]] wavelength lost energy before hitting the fuel. Breakthroughs were made at LLE at [[Organization:University of Rochester|University of Rochester]]. Rochester scientists used frequency-tripling crystals to transform infrared laser beams into ultraviolet beams.

==== Chirping ====
In 1985, [[Biography:Donna Strickland|Donna Strickland]]<ref>{{cite web|title=Dr. Donna Strickland {{pipe}} Science|url=https://uwaterloo.ca/science/magnet-talent-more-stories/dr-donna-strickland|url-status=dead|archive-url=https://web.archive.org/web/20140111204111/https://uwaterloo.ca/science/magnet-talent-more-stories/dr-donna-strickland|archive-date=2014-01-11|access-date=2014-08-24|publisher=Uwaterloo.ca}}</ref> and [[Biography:Gérard Mourou|Gérard Mourou]] invented a method to amplify laser pulses by "chirping". This changed a single wavelength into a full spectrum. The system amplified the beam at each wavelength and then reversed the beam into one color. Chirp pulsed amplification became instrumental for NIF and the Omega EP system.<ref>{{Cite book|url=https://www.worldcat.org/oclc/153575814|title=Inertial confinement nuclear fusion : a historical approach by its pioneers|date=2007|publisher=Foxwell & Davies (UK)|editor1=Verlarde, Guillermo |editor2=Carpintero Santamaría, Natividad|isbn=978-1-905868-10-0|location=London, U.K.|oclc=153575814}}</ref>

LANL constructed a series of laser facilities.<ref name="NRDC">{{cite web|author1=Dr. Matthew McKinzie|author2=Christopher E. Paine|date=2000|title=When peer review fails : The Roots of the National Ignition Facility (NIF) Debacle|url=http://www.nrdc.org/nuclear/nif2/findings.asp|access-date=30 October 2014|publisher=National Resources Defense Council}}</ref> They included Gemini (a two beam system), Helios (eight beams), Antares (24 beams) and Aurora (96 beams).<ref>{{Cite book|last1=Los Alamos National Laboratory|url=http://www.osti.gov/servlets/purl/5668574-sHjbqu/|title=Recent progress on the Los Alamos Aurora ICF (inertial confinement fusion) laser system.|date=1987|publisher=Los Alamos National Laboratory; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy|location=Los Alamos, N.M.; Oak Ridge, Tenn.|language=en|oclc=727275288}}</ref><ref>{{cite web|date=2014-06-20|title=Los Alamos National Labs Aurora Laser Fusion Project {{pipe}} Hextek Corp|url=http://www.hextek.com/applications-projects/los-alamos-national-labs%E2%80%A8aurora-laser-fusion-project/|url-status=dead|archive-url=https://web.archive.org/web/20140517211657/http://www.hextek.com/applications-projects/los-alamos-national-labs%E2%80%A8aurora-laser-fusion-project/|archive-date=May 17, 2014|access-date=2014-08-24|publisher=Hextek.com}}</ref> The program ended in the early nineties with a cost on the order of one billion dollars.<ref name="NRDC" />

In 1987, Akira Hasegawa<ref>{{Cite journal|last=Hasegawa|first=Akira|date=1987|title=A dipole field fusion reactor|url=http://inis.iaea.org/Search/search.aspx?orig_q=RN:21025528|journal=Comments on Plasma Physics and Controlled Fusion|language=en|volume=11|issue=3|pages=147–151|issn=0374-2806}}</ref> noticed that in a dipolar magnetic field, fluctuations tended to compress the plasma without energy loss. This effect was noticed in data taken by [[Astronomy:Voyager 2|Voyager 2]], when it encountered [[Astronomy:Uranus|Uranus]]. This observation became the basis for a fusion approach known as the [[Physics:Levitated dipole|levitated dipole]].

In tokamaks, the Tore Supra was under construction from 1983 to 1988 in [[Physics:Cadarache|Cadarache]], France.<ref name="auto1">{{cite web|title=Tore Supra|url=http://www-drfc.cea.fr/gb/cea/ts/ts.htm|url-status=dead|archive-url=https://web.archive.org/web/20121115112229/http://www-drfc.cea.fr/gb/cea/ts/ts.htm|archive-date=November 15, 2012|access-date=February 3, 2016}}</ref> Its [[Physics:Superconductivity|superconducting]] magnets permitted it to generate a strong permanent toroidal magnetic field.<ref>{{Cite web|date=2001|title=Tore Supra (photo)|url=http://www-drfc.cea.fr/gb/cea/ts/ts.htm|url-status=live|archive-url=https://web.archive.org/web/20121115112229/http://www-drfc.cea.fr/gb/cea/ts/ts.htm|archive-date=November 15, 2012|access-date=2021-06-14}}</ref> First plasma came in 1988.<ref>{{cite web|title=The Tore Supra Tokamak|url=http://www-fusion-magnetique.cea.fr/cea/ts/resultats.htm|archive-url=https://web.archive.org/web/20110211105510/http://www-fusion-magnetique.cea.fr/cea/ts/resultats.htm|archive-date=11 February 2011|access-date=20 July 2015|publisher=CEA}}</ref>

In 1983, [[Physics:Joint European Torus|JET]] achieved first plasma. In 1985, the Japanese tokamak, [[Physics:JT-60|JT-60]] produced its first plasmas. In 1988, the [[Physics:T-15 (reactor)|T-15]] a Soviet tokamak was completed, the first to use (helium-cooled) [[Physics:Superconducting|superconducting]] magnets.<ref>{{Cite journal|last=Smirnov|first=V.P.|date=2009-12-30|title=Tokamak foundation in USSR/Russia 1950–1990|journal=Nuclear Fusion|volume=50|issue=1|pages=014003|doi=10.1088/0029-5515/50/1/014003|bibcode=2010NucFu..50a4003S |s2cid=17487157 |issn=0029-5515|doi-access=free}}</ref>

In 1998, the [[Physics:T-15 (reactor)|T-15]] Soviet tokamak with superconducting helium-cooled coils was completed.

=== Spherical tokamak ===
In 1984, Martin Peng proposed<ref>Y-K Martin Peng, "Spherical Torus, Compact Fusion at Low Yield"., ORNL/FEDC-87/7 (December 1984)</ref> an alternate arrangement of magnet coils that would greatly reduce the aspect ratio while avoiding the erosion issues of the compact tokamak: a [[Physics:Spherical tokamak|spherical tokamak]]. Instead of wiring each magnet coil separately, he proposed using a single large conductor in the center, and wiring the magnets as half-rings off of this conductor. What was once a series of individual rings passing through the hole in the center of the reactor was reduced to a single post, allowing for aspect ratios as low as 1.2.<ref name=":21">{{Cite journal|last=Sykes|first=Alan|date=1997|title=High β produced by neutral beam injection in the START (Small Tight Aspect Ratio Tokamak) spherical tokamak|journal=Physics of Plasmas|language=en|volume=4|issue=5|pages=1665–1671|bibcode=1997PhPl....4.1665S|doi=10.1063/1.872271|issn=1070-664X|doi-access=free}}</ref><sup>:B247</sup><ref name=":222">{{Cite book|last=Braams, C. M. |url=https://www.worldcat.org/oclc/1107880260|title=Nuclear fusion : half a century of magnetic confinement fusion research|others=Stott, P. E. (Peter E.)|year=2002|isbn=978-0-367-80151-9|location=[Place of publication not identified]|oclc=1107880260}}</ref><sup>:225</sup> The ST concept appeared to represent an enormous advance in tokamak design. The proposal came during a period when US fusion research budgets were dramatically smaller. ORNL was provided with funds to develop a suitable central column built out of a high-strength copper alloy called "Glidcop". However, they were unable to secure funding to build a demonstration machine.

Failing at ORNL, Peng began a worldwide effort to interest other teams in the concept and get a test machine built. One approach would be to convert a spheromak.<ref name=":222" /><sup>:225</sup> Peng's advocacy caught the interest of Derek Robinson, of the United Kingdom Atomic Energy Authority. Robinson gathered a team and secured on the order of 100,000 pounds to build an experimental machine, the [[Physics:Small Tight Aspect Ratio Tokamak|Small Tight Aspect Ratio Tokamak]], or START. Parts of the machine were recycled from earlier projects, while others were loaned from other labs, including a 40 keV neutral beam injector from ORNL. Construction began in 1990 and operation started in January 1991.<ref name=":21" /><sup>:11</sup> It achieved a record [[Physics:Fusion power#Beta|beta]] (plasma pressure compared to magnetic field pressure) of 40% using a neutral beam injector

=== ITER ===
The International Thermonuclear Experimental Reactor ([[Organization:ITER|ITER]]) coalition forms, involving EURATOM, Japan, the Soviet Union and United States and kicks off the conceptual design process.

== 1990s ==<!--{{multiple image
 | width1 = 220
 | image1 = WP:NFCC violation: Z-machine480.jpg
 | caption1 = Z Machine (a pinch at SNL) went through a number of upgrades during the mid to late nineties }}-->
[[File:Nif_hohlraum.jpg|thumb|Mockup of a gold-plated hohlraum designed for use in the [[Organization:National Ignition Facility|National Ignition Facility]]]]
In 1991 JET's Preliminary Tritium Experiment achieved the world's first controlled release of fusion power.<ref>{{Cite journal|last1=Jarvis|first1=O. N.|date=2006-06-16|title=Neutron measurements from the preliminary tritium experiment at JET (invited)|journal=Review of Scientific Instruments|volume=63|issue=10|pages=4511–4516|doi=10.1063/1.1143707}}</ref>

In 1992, ''Physics Today'' published Robert McCory's outline of the current state of ICF, advocating for a national ignition facility.<ref>{{Cite journal|last1=Lindl|first1=John|last2=McCrory|first2=Robert L.|last3=Campbell|first3=E. Michael|date=1992|title=Progress Toward Ignition and Burn Propagation in Inertial Confinement Fusion|url=http://www.physics.utoronto.ca/~phy189h1/Ignition%20and%20Inertial%20Confinement%20Fusion.pdf|journal=Physics Today|volume=45|issue=9|pages=32–40|bibcode=1992PhT....45i..32L|doi=10.1063/1.881318}}</ref> This was followed by a review article from John Lindl in 1995,<ref>{{Cite journal|last=Lindl|first=John|date=1995-11-01|title=Development of the indirect-drive approach to inertial confinement fusion and the target physics basis for ignition and gain|url=https://zenodo.org/record/1232083|journal=Physics of Plasmas|volume=2|issue=11|pages=3933–4024|bibcode=1995PhPl....2.3933L|doi=10.1063/1.871025|issn=1070-664X}}</ref> making the same point. During this time various ICF subsystems were developed, including target manufacturing, cryogenic handling systems, new laser designs (notably the [[Engineering:Nike laser|NIKE laser]] at NRL) and improved diagnostics including time of flight analyzers and [[Physics:Thomson scattering|Thomson scattering]]. This work was done at the [[Engineering:Nova (laser)|NOVA]] laser system, General Atomics, [[Engineering:Laser Mégajoule|Laser Mégajoule]] and the [[Engineering:GEKKO XII|GEKKO XII]] system in Japan. Through this work and lobbying by groups like the fusion power associates and John Sethian at NRL, Congress authorized funding for the [[Organization:National Ignition Facility|NIF]] project in the late nineties.

In 1992 the United States and the former republics of the Soviet Union stopped testing nuclear weapons.

In 1993 TFTR at PPPL experimented with 50% [[Physics:Deuterium|deuterium]], 50% [[Physics:Tritium|tritium]], eventually reaching 10 megawatts.

In the early nineties, theory and experimental work regarding fusors and [[Physics:Polywell|polywell]]s was published.<ref>{{cite journal|last1=Krall|first1=N. A.|last2=Coleman|first2=M.|last3=Maffei|first3=K.|last4=Lovberg|first4=J.|last5=Jacobsen|first5=R.|last6=Bussard|first6=R. W.|year=1995|title=Forming and maintaining a potential well in a quasispherical magnetic trap|journal=Physics of Plasmas|volume=2|issue=1|page=146|bibcode=1995PhPl....2..146K|doi=10.1063/1.871103|doi-access=free}}</ref><ref>"Inertial electrostatic fusion (IEF): A clean energy future" (Microsoft Word document). Energy/Matter Conversion Corporation. Retrieved 2006-12-03.</ref> In response, Todd Rider at MIT developed general models of these devices,<ref>{{Cite thesis|url=http://hdl.handle.net/1721.1/11412|title=Fundamental limitations on plasma fusion systems not in thermodynamic equilibrium|date=2005|publisher=Massachusetts Institute of Technology|hdl=1721.1/11412|language=en|oclc=1135080625|type=Thesis}}</ref> arguing that all plasma systems at thermodynamic equilibrium were fundamentally limited. In 1995, William Nevins published a criticism<ref>{{cite journal|last1=Nevins|first1=William M|year=1995|title=Can Inertial Electrostatic Confinement Work beyond the Ion-ion Collisional Time Scale?|url=https://digital.library.unt.edu/ark:/67531/metadc688729/|url-status=dead|journal=Physics of Plasmas|volume=2|issue=10|pages=3804–819|bibcode=1995PhPl....2.3804N|doi=10.1063/1.871080|archive-url=https://web.archive.org/web/20200709210855/https://digital.library.unt.edu/ark:/67531/metadc688729/|archive-date=July 9, 2020|access-date=July 8, 2020}}</ref> arguing that the particles inside fusors and polywells would acquire [[Physics:Angular momentum|angular momentum]], causing the dense core to degrade.

In 1995, the [[Organization:University of Wisconsin–Madison|University of Wisconsin–Madison]] built a large [[Physics:Fusor|fusor]], known as HOMER.<ref>{{cite web|title="IEC Lab Timeline" accessed 1-25-2014|url=http://iec.neep.wisc.edu/results.php|access-date=30 October 2014|publisher=Iec.neep.wisc.edu}}</ref> Dr [[Biography:George H. Miley|George H. Miley]] at [[Organization:University of Illinois at Urbana–Champaign|Illinois]] built a small fusor that produced neutrons using deuterium<ref>{{Cite journal|last=Miley|first=George H.|date=1999-02-11|title=A portable neutron/tunable X-ray source based on inertial electrostatic confinement|url=http://www.sciencedirect.com/science/article/pii/S0168900298011085|journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|language=en|volume=422|issue=1|pages=16–20|bibcode=1999NIMPA.422...16M|doi=10.1016/S0168-9002(98)01108-5|issn=0168-9002}}</ref><ref>{{Cite journal|last=Miley|first=George H.|date=2001|title=A portable neutron/tunable x-ray source based on inertial electrostatic confinement|url=http://dx.doi.org/10.1063/1.1395401|journal=AIP Conference Proceedings|publisher=AIP|volume=576|pages=683–686|bibcode=2001AIPC..576..683M|doi=10.1063/1.1395401}}</ref> and discovered the "[[Physics:Fusor#Star mode|star mode]]" of fusor operation. At this time in Europe, an IEC device was developed as a commercial neutron source by Daimler-Chrysler and NSD Fusion.<ref>{{cite web|title=NSD-GRADEL-FUSION - Neutron Generators|url=http://www.nsd-fusion.com|access-date=2014-08-24|publisher=Nsd-fusion.com}}</ref><ref>{{Cite journal|last1=Miley|first1=George H.|last2=Sved|first2=J.|date=2000|title=The IEC star-mode fusion neutron source for NAA — status and next-step designs|url=http://dx.doi.org/10.1016/s0969-8043(00)00215-3|journal=Applied Radiation and Isotopes|volume=53|issue=4–5|pages=779–783|doi=10.1016/s0969-8043(00)00215-3|issn=0969-8043|pmid=11003520}}</ref>

The next year, Tore Supra reached a record plasma duration of two minutes with a current of almost 1 M amperes driven non-inductively by 2.3 MW of [[Physics:Lower hybrid oscillation|lower hybrid frequency waves]] (i.e. 280 MJ of injected and extracted energy), enabled by actively cooled plasma-facing components.<ref name="auto1" /><ref>{{Cite journal|last=Garin|first=Pascal|date=October 2001|title=Actively cooled plasma facing components in Tore Supra|url=http://dx.doi.org/10.1016/s0920-3796(01)00242-3|journal=Fusion Engineering and Design|volume=56-57|pages=117–123|doi=10.1016/s0920-3796(01)00242-3|issn=0920-3796}}</ref>

The upgraded Z-machine opened to the public in August 1998.<ref>{{cite web|last=Yonas|first=Gerold|title=Fusion nucléaire et striction axiale|url=http://www.pescadoo.net/malc/art-6.htm|url-status=dead|archive-url=https://web.archive.org/web/20121004233022/http://www.pescadoo.net/malc/art-6.htm|archive-date=October 4, 2012|access-date=October 4, 2012|language=fr}}</ref> The key attributes were its 18&nbsp;million ampere current and a discharge time of less than 100 [[Second|nanoseconds]].<ref>{{cite web|date=August 1, 1997|title=Output of Sandia Z Accelerator Climbs Closer to Fusion|url=http://www.sandia.gov/media/zmachine.htm|access-date=2014-08-24|publisher=Sandia.gov}}</ref> This generated a magnetic pulse inside a large oil tank, which struck a liner (an array of [[Chemistry:Tungsten|tungsten]] wires).<ref>{{cite web|title=Another dramatic climb toward fusion conditions for Sandia Z accelerator|url=http://www.sandia.gov/media/z290.htm|access-date=2014-08-24|publisher=Sandia.gov}}</ref> Firing the Z-machine became a way to test high energy, high temperature (2&nbsp;billion degrees) conditions.<ref>{{cite web|date=December 2, 1996|title=High-Output Sandia Accelerator Able to Predict Nuclear Blast Physics|url=http://www.sandia.gov/media/zpinch.htm|access-date=2014-08-24|publisher=Sandia.gov}}</ref> In 1996.

In 1997, JET reached 16.1&nbsp;MW (65% of heat to plasma<ref>[http://fusionforenergy.europa.eu/downloads/mediacorner/publications/reports/fusion_research_english.pdf FUSION RESEARCH An Energy Option for An Energy Option for Europe's Future ], pa. 27</ref>), sustaining over 10&nbsp;MW for over 0.5&nbsp;sec. As of 2020 this remained the record output level. Four megawatts of [[Physics:Alpha particle|alpha particle]] self-heating was achieved.

ITER was officially announced as part of a seven-party consortium (six countries and the EU). ITER was designed to produce ten times more fusion power than the input power. ITER was sited in Cadarache.<ref>{{Cite book|last=Claessens|first=Michel|url=http://dx.doi.org/10.1007/978-3-030-27581-5|title=ITER: The Giant Fusion Reactor|date=2020|isbn=978-3-030-27580-8|doi=10.1007/978-3-030-27581-5|s2cid=243590344}}</ref> The US withdrew from the project in 1999.

JT-60 produced a reversed shear plasma with the equivalent fusion amplification factor <math>Q_{eq}</math> of 1.25 - as of 2021 this remained the world record.

In the late nineties, a team at [[Organization:Columbia University|Columbia University]] and MIT developed the [[Physics:Levitated dipole|levitated dipole]],<ref>{{Cite tech report|last1=Hasegawa|first1=Akira|last2=Chen|first2=Liu|date=1989-07-01|title=A D-He/sup 3/ fusion reactor based on a dipole magnetic field|url=http://dx.doi.org/10.2172/5819503|doi=10.2172/5819503}}</ref> a fusion device that consisted of a superconducting electromagnet, floating in a saucer shaped vacuum chamber.<ref>{{Cite journal|last=Tsventoukh|first=M. M.|date=2007|title=Plasma equilibrium in a double-dipole magnetic confinement system with a separatrix|url=http://dx.doi.org/10.1134/s1063780x07070021|journal=Plasma Physics Reports|volume=33|issue=7|pages=535–542|bibcode=2007PlPhR..33..535T|doi=10.1134/s1063780x07070021|issn=1063-780X|s2cid=121783405}}</ref> Plasma swirled around this donut and fused along the center axis.<ref>{{Cite web|title=MIT tests unique approach to fusion power|url=https://news.mit.edu/2008/ldx-tt0319|access-date=2020-10-12|website=MIT News {{!}} Massachusetts Institute of Technology|date=19 March 2008 |language=en}}</ref>

In 1999 [[Physics:Mega Ampere Spherical Tokamak|MAST]] replaced [[Physics:Small Tight Aspect Ratio Tokamak|START]].

== 2000s ==
[[File:Homemade_fusion_reactor.JPG|thumb|Starting in 1999, a growing number of amateurs have been able to fuse atoms using homemade fusors, shown here.<ref>{{cite web|title=Fusor Forums • Index page|url=http://www.fusor.net/board/|access-date=2014-08-24|publisher=Fusor.net}}</ref><ref>{{cite web|date=2012-03-23|title=Build a Nuclear Fusion Reactor? No Problem|url=http://www.clhsonline.net/sciblog/index.php/2012/03/build-a-nuclear-fusion-reactor-no-problem/|url-status=dead|archive-url=https://web.archive.org/web/20141030210524/http://www.clhsonline.net/sciblog/index.php/2012/03/build-a-nuclear-fusion-reactor-no-problem/|archive-date=2014-10-30|access-date=2014-08-24|publisher=Clhsonline.net}}</ref><ref>{{cite news|last1=Danzico|first1=Matthew|date=2010-06-23|title=Extreme DIY: Building a homemade nuclear reactor in NYC|website=BBC News|url=https://www.bbc.co.uk/news/10385853|access-date=30 October 2014}}</ref><ref>{{cite web|last=Schechner|first=Sam|date=2008-08-18|title=Nuclear Ambitions: Amateur Scientists Get a Reaction From Fusion - WSJ|url=https://www.wsj.com/news/articles/SB121901740078248225|url-status=dead|archive-url=https://web.archive.org/web/20151011210355/http://www.wsj.com/news/articles/SB121901740078248225|archive-date=2015-10-11|access-date=2014-08-24|publisher=Online.wsj.com}}</ref>]]
[[File:MAST_plasma_image.jpg|thumb|The [[Physics:Mega Ampere Spherical Tokamak|Mega Ampere Spherical Tokamak]] became operational in the UK in 1999]]
"Fast ignition"<ref>{{Cite book|last=Atzeni, Stefano|url=https://www.worldcat.org/oclc/56645784|title=The physics of inertial fusion : beam plasma interaction, hydrodynamics, hot dense matter|date=2004|publisher=Clarendon Press|others=Meyer-ter-Vehn, Jürgen|isbn=978-0-19-856264-1|location=Oxford|oclc=56645784}}</ref><ref>{{Cite book|last=Pfalzner|first=Susanne|url=http://dx.doi.org/10.1201/9781420011845|title=An Introduction to Inertial Confinement Fusion|date=2006-03-02|publisher=CRC Press|isbn=978-0-429-14815-6|doi=10.1201/9781420011845}}</ref> appeared in the late nineties, as part of a push by LLE to build the Omega EP system, which finished in 2008. Fast ignition showed dramatic power savings and moved ICF into the race for energy production. The [[Engineering:HiPER|HiPER]] experimental facility became dedicated to fast ignition.

In 2001 the United States, China and Republic of Korea joined ITER while Canada withdrew.

In April 2005, a UCLA team announced<ref>{{cite web|date=2006-10-21|title=The Year in Science: Physics|url=https://discover.com/issues/jan-06/features/physics/|url-status=dead|archive-url=https://archive.today/20061021025402/https://discover.com/issues/jan-06/features/physics/|archive-date=October 21, 2006|access-date=2013-06-22}}</ref> a way of producing fusion using a machine that "fits on a lab bench", using [[Chemistry:Lithium tantalate|lithium tantalate]] to [[Physics:Pyroelectric fusion|generate enough voltage to fuse deuterium]]. The process did not generate net power.

The next year, China's [[Physics:Experimental Advanced Superconducting Tokamak|EAST]] test reactor was completed.<ref>{{Cite web|title=People's Daily Online -- China to build world's first "artificial sun" experimental device|url=http://en.people.cn/200601/21/eng20060121_237208.html|access-date=2020-10-10|website=en.people.cn}}</ref> This was the first tokamak to use superconducting magnets to generate both toroidal and poloidal fields.

In the early 2000s, [[Organization:LANL|LANL]] researchers claimed that an oscillating plasma could reach local thermodynamic equilibrium. This prompted the POPS and [[Physics:Penning trap|Penning trap]] designs.<ref>{{Cite journal|last1=Barnes|first1=D. C.|last2=Chacón|first2=L.|last3=Finn|first3=J. M.|date=2002|title=Equilibrium and low-frequency stability of a uniform density, collisionless, spherical Vlasov system|url=http://dx.doi.org/10.1063/1.1510667|journal=Physics of Plasmas|volume=9|issue=11|pages=4448–4464|bibcode=2002PhPl....9.4448B|doi=10.1063/1.1510667|issn=1070-664X}}</ref><ref>{{Cite journal|last1=Mitchell|first1=T. B.|last2=Schauer|first2=M. M.|last3=Barnes|first3=D. C.|date=1997-01-06|title=Observation of Spherical Focus in an Electron Penning Trap|url=http://dx.doi.org/10.1103/physrevlett.78.58|journal=Physical Review Letters|volume=78|issue=1|pages=58–61|bibcode=1997PhRvL..78...58M|doi=10.1103/physrevlett.78.58|issn=0031-9007}}</ref>

In 2005 NIF fired its first bundle of eight beams, achieving the most powerful laser pulse to date - 152.8 kJ (infrared).

MIT researchers became interested in fusors for space propulsion,<ref>{{Cite thesis|url=http://hdl.handle.net/1721.1/39702|title=Improving particle confinement in inertial electrostatic fusion for spacecraft power and propulsion|date=2007|publisher=Massachusetts Institute of Technology|hdl=1721.1/39702|language=en|oclc=1138885569|type=Thesis|last1=Dietrich|first1=Carl}}</ref> using fusors with multiple inner cages.<ref>{{Cite thesis|title=Improved lifetimes and synchronization behavior in multi-grid inertial electrostatic confinement fusion devices|url=https://dspace.mit.edu/handle/1721.1/38527|publisher=Massachusetts Institute of Technology|date=2007|degree=Thesis|first=Thomas John|last=McGuire|hdl=1721.1/38527}}</ref> Greg Piefer founded Phoenix Nuclear Labs and developed the fusor into a neutron source for [[Medicine:Isotopes in medicine|medical isotope]] production.<ref>{{Cite web|title=Phoenix Nuclear Labs: Phoenix Nuclear Labs meets neutron production milestone {{!}} WisBusiness|date=May 2013 |url=https://www.wisbusiness.com/2013/phoenix-nuclear-labs-phoenix-nuclear-labs-meets-neutron-production-milestone/|access-date=2020-10-11|language=en-US}}</ref> Robert Bussard began speaking openly about the [[Physics:Polywell|polywell]] in 2006.<ref>SirPhilip (posting an e-mail from "RW Bussard") (2006-06-23). "Fusion, eh?". James Randi Educational Foundation forums. Retrieved 2006-12-03.</ref><ref>{{Citation|last=Bussard|first=Robert W|title=The Advent of Clean Nuclear Fusion: Superperformance Space Power and Propulsion|date=2006-10-02|url=https://arc.aiaa.org/doi/10.2514/6.IAC-06-D2.8.05|work=57th International Astronautical Congress|series=International Astronautical Congress (IAF)|publisher=American Institute of Aeronautics and Astronautics|doi=10.2514/6.iac-06-d2.8.05|isbn=978-1-62410-042-0|access-date=2020-10-11}}</ref>

In March 2009, NIF became operational.<ref>[https://lasers.llnl.gov/about/what-is-nif What is NIF?] {{Webarchive|url=https://web.archive.org/web/20170731064919/https://lasers.llnl.gov/about/what-is-nif|date=July 31, 2017}}, Lawrence Livermore National Laboratory.</ref>

In the early 2000s privately backed fusion companies launched to develop commercial fusion power.<ref name=":0">{{Cite journal|last=Clery|first=Daniel|date=2014-07-25|title=Fusion's restless pioneers|journal=Science|language=en|volume=345|issue=6195|pages=370–375|bibcode=2014Sci...345..370C|doi=10.1126/science.345.6195.370|issn=0036-8075|pmid=25061186|ref=none}}</ref> Tri Alpha Energy, founded in 1998, began by exploring a [[Physics:Field-reversed configuration|field-reversed configuration]] approach.<ref name=":1">{{Cite web|last=Frochtzwajg|first=Jonathan|title=The secretive, billionaire-backed plans to harness fusion|url=http://www.bbc.com/future/story/20160428-the-secretive-billionaire-backed-plans-to-harness-fusion|access-date=2017-08-21|website=BBC}}</ref><ref>{{Cite news|last=Kanellos|first=Michael|title=Hollywood, Silicon Valley and Russia Join Forces on Nuclear Fusion|language=en|work=Forbes|url=https://www.forbes.com/sites/michaelkanellos/2013/03/11/hollywood-silicon-valley-and-russia-join-forces-on-nuclear-fusion/#12c2795972ba|access-date=2017-08-21}}</ref> In 2002, Canadian company [[Company:General Fusion|General Fusion]] began proof-of-concept experiments based on a hybrid magneto-inertial approach called [[Physics:Magnetized target fusion|Magnetized Target Fusion.]]<ref name=":1" /><ref name=":0" /> Investors included [[Biography:Jeff Bezos|Jeff Bezos]] (General Fusion) and [[Biography:Paul Allen|Paul Allen]] (Tri Alpha Energy).<ref name=":1" /> Toward the end of the decade, [[Company:Tokamak Energy|Tokamak Energy]] started exploring spherical tokamak devices using reconnection.<ref>{{Cite web|last=Gray|first=Richard|title=The British reality TV star building a fusion reactor|url=http://www.bbc.com/future/story/20170418-the-made-in-chelsea-star-building-a-fusion-reactor|access-date=2017-08-21}}</ref>

== 2010s ==
[[File:Preamplifier_at_the_National_Ignition_Facility.jpg|right|thumb|The preamplifiers of the National Ignition Facility. In 2012, the NIF achieved a 500-terawatt shot.]]
[[File:Wendelstein7-X_Torushall-2011.jpg|right|thumb|The Wendelstein7X under construction]]
[[File:W7X-Spulen_Plasma_blau_gelb.jpg|thumb|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.]]
[[File:Electra Laser Generates 90K Shots.webm|thumb|alt=The Naval Research Laboratory demonstrated over 90,000 shots in 10 hours in 2013. |The Naval Research Laboratory demonstrated over 90,000 shots in 10 hours in 2013.<ref>Obenschain, Stephen, et al. "High-energy krypton fluoride lasers for inertial fusion." Applied optics 54.31 (2015): F103-F122.</ref>]]
Private and public research accelerated in the 2010s.

=== Private projects ===
In 2017, [[Company:General Fusion|General Fusion]] developed its plasma injector technology and Tri Alpha Energy constructed and operated its C-2U device.<ref>{{Cite journal|last=Clery|first=Daniel|date=2017-04-28|title=Private fusion machines aim to beat massive global effort|journal=Science|language=en|volume=356|issue=6336|pages=360–361|bibcode=2017Sci...356..360C|doi=10.1126/science.356.6336.360|issn=0036-8075|pmid=28450588|s2cid=206621512}}</ref> In August 2014, Phoenix Nuclear Labs announced the sale of a high-yield neutron generator that could sustain 5×10<sup>11</sup> deuterium fusion reactions per second over a 24-hour period.<ref name="auto9">{{cite web|year=2013|title=The Alectryon High Yield Neutron Generator|url=http://phoenixnuclearlabs.com/product/high-yield-neutron-generator/|publisher=Phoenix Nuclear Labs}}</ref>

In October 2014, [[Company:Lockheed Martin|Lockheed Martin]]'s [[Engineering:Skunk Works|Skunk Works]] announced the development of a high [[Physics:Beta (plasma physics)|beta]] fusion reactor, the [[Physics:Lockheed Martin Compact Fusion Reactor|Compact Fusion Reactor]].<ref>{{cite web|title=FuseNet: The European Fusion Education Network|url=http://www.fusenet.eu/node/400|access-date=30 October 2014|publisher=Fusenet.eu}}</ref><ref>{{cite news|year=2013|title=Fusion Power Could Happen Sooner Than You Think|work=Popular Science|url=http://www.popsci.com/technology/article/2013-02/fusion-power-could-happen-sooner-you-think|access-date=30 October 2014}}</ref><ref>{{cite news|date=2014-10-15|title=Nuclear fusion energy in a decade? Lockheed Martin is betting on it.|newspaper={{wipe|The Washington Post}}|url=https://www.washingtonpost.com/news/capital-business/wp/2014/10/15/nuclear-fusion-energy-in-a-decade-lockheed-martin-is-betting-on-it/|access-date=30 October 2014}}</ref> Although the original concept was to build a 20-ton, container-sized unit, the team conceded in 2018 that the minimum scale would be 2,000 tons.<ref name=":2">{{Cite web|last=Wang|first=Brian|date=August 1, 2018|title=Nuclear Fusion Updated project reviews|url=https://www.nextbigfuture.com/2018/08/nuclear-fusion-updated-project-reviews.html|access-date=2018-08-03|website=www.nextbigfuture.com|language=en-US}}</ref>

In January 2015, the polywell was presented at [[Organization:Microsoft Research|Microsoft Research]].<ref name="auto8">{{cite web|title=Microsoft Research – Emerging Technology, Computer, and Software Research|url=https://www.microsoft.com/en-us/research/|website=Microsoft Research}}</ref> [[Company:TAE Technologies|TAE Technologies]] announced that its Norman reactor had achieved plasma.<ref>{{cite news|last=Boyle|first=Alan|date=10 July 2017|title=With Paul Allen's Backing, Tri Alpha Energy Revs Up 'Norman' Device for Fusion Research|work=GeekWire|url=https://www.geekwire.com/2017/paul-allens-backing-tri-alpha-energy-revs-norman-device-fusion-research/}}</ref>

In 2017, [[Company:Helion Energy|Helion Energy]]'s fifth-generation plasma machine went into operation, seeking to achieve plasma density of 20 T and fusion temperatures.<ref name=":2" /> [[Company:Tokamak Energy|ST40]] generated "first plasma".<ref name="auto2">{{Cite web|last=MacDonald|first=Fiona|title=The UK Just Switched on an Ambitious Fusion Reactor - And It Works|url=https://www.sciencealert.com/the-uk-has-just-switch-on-its-tokamak-nuclear-fusion-reactor|access-date=2019-07-03|website=ScienceAlert|date=May 2017 |language=en-gb}}</ref>

In 2018, [[Company:Eni|Eni]] announced a $50&nbsp;million investment in [[Company:Commonwealth Fusion Systems|Commonwealth Fusion Systems]], to attempt to commercialize [[Physics:ARC fusion reactor|ARC]] technology using a test reactor ([[Physics:SPARC (tokamak)|SPARC]]) in collaboration with MIT.<ref name="auto7">{{cite news|date=13 April 2018|title=Italy's Eni defies sceptics, may up stake in nuclear fusion project|newspaper=Reuters|url=https://www.reuters.com/article/us-nuclearpower-fusion-eni/italys-eni-defies-skeptics-may-up-stake-in-nuclear-fusion-project-idUSKBN1HK1JJ}}</ref><ref name="auto11">{{cite web|date=3 April 2018|title=MIT Aims to Harness Fusion Power Within 15 years|url=https://www.seeker.com/energy/mit-aims-to-harness-fusion-power-within-15-years}}</ref><ref name="auto">{{cite web|date=9 March 2018|title=MIT Aims To Bring Nuclear Fusion To The Market In 10 Years|url=http://www.wbur.org/bostonomix/2018/03/09/mit-nuclear-fusion}}</ref><ref>{{cite web|date=9 March 2018|title=MIT and newly formed company launch novel approach to fusion power|url=https://news.mit.edu/2018/mit-newly-formed-company-launch-novel-approach-fusion-power-0309}}</ref> The reactor planned to employ [[Chemistry:Yttrium barium copper oxide|yttrium barium copper oxide]] (YBCO) high-temperature superconducting magnet technology. Commonwealth Fusion Systems in 2021 tested successfully a 20 T magnet making it the strongest high-temperature superconducting magnet in the world. Following the 20 T magnet CFS raised $1.8 billion from private investors.

General Fusion began developing a 70% scale demo system.<ref name=":222"/> In 2018, TAE Technologies' reactor reached nearly 20 M°C.<ref>{{cite news|title=TAE Technologies Pushes Plasma Machine to a New High on the Nuclear Fusion Frontier|work=GeekWire|url=https://www.geekwire.com/2018/tae-technologies-pushes-plasma-machine-new-high-fusion-frontier/}}</ref>

=== Government and academic projects ===
In 2010, NIF researchers conducted a series of "tuning" shots to determine the optimal target design and laser parameters for high-energy ignition experiments with fusion fuel.<ref>{{cite web|last=Seaver|first=Lynda L.|date=2010-10-01|title=World's largest laser sets records for neutron yield and laser energy|url=https://www.llnl.gov/news/newsreleases/2010/Nov/NR-10-11-02.html|access-date=2013-06-22|publisher=Lawrence Livermore National Laboratory}}</ref><ref name="Oct8_10">{{cite news|date=October 8, 2010|title=First successful integrated experiment at National Ignition Facility announced|work=General Physics|publisher=PhysOrg.com|url=http://www.physorg.com/news205740709.html|access-date=2010-10-09}}</ref> Net fuel energy gain<ref>{{cite web|author=SPIE Europe Ltd|title=PW 2012: fusion laser on track for 2012 burn|url=http://optics.org/news/3/1/37|access-date=2013-06-22|publisher=Optics.org}}</ref><ref>{{Cite journal |last1=Hurricane |first1=O. A. |last2=Callahan |first2=D. A. |last3=Casey |first3=D. T. |last4=Celliers |first4=P. M. |last5=Cerjan |first5=C. |last6=Dewald |first6=E. L. |last7=Dittrich |first7=T. R. |last8=Döppner |first8=T. |last9=Hinkel |first9=D. E. |last10=Hopkins |first10=L. F. Berzak |last11=Kline |first11=J. L. |last12=Le Pape |first12=S. |last13=Ma |first13=T. |last14=MacPhee |first14=A. G. |last15=Milovich |first15=J. L. |date=February 2014 |title=Fuel gain exceeding unity in an inertially confined fusion implosion |url=https://www.nature.com/articles/nature13008 |journal=Nature |language=en |volume=506 |issue=7488 |pages=343–348 |doi=10.1038/nature13008 |pmid=24522535 |s2cid=4466026 |issn=1476-4687}}</ref> was achieved in September 2013.<ref>{{cite news|title=Nuclear fusion milestone passed at US lab|work=BBC News|url=https://www.bbc.co.uk/news/science-environment-24429621|access-date=30 October 2014}}</ref><ref>{{cite journal|last1=Herrmann|first1=Mark|date=20 February 2014|title=Plasma physics: A promising advance in nuclear fusion|journal=Nature|volume=506|issue=7488|pages=302–303|bibcode=2014Natur.506..302H|doi=10.1038/nature13057|pmid=24522529|doi-access=free}}</ref>

In April 2014, LLNL ended the [[Physics:Inertial confinement fusion|Laser Inertial Fusion Energy]] (LIFE) program and directed their efforts towards NIF.<ref>{{Cite journal|last=Kramer|first=David|date=2014-04-01|title=Livermore ends LIFE|journal=Physics Today|volume=67|issue=4|pages=26–27|bibcode=2014PhT....67R..26K|doi=10.1063/PT.3.2344|s2cid=178876869}}</ref>

A 2012 paper demonstrated that a dense plasma focus had achieved temperatures of 1.8&nbsp;billion degrees Celsius, sufficient for boron fusion, and that fusion reactions were occurring primarily within the contained plasmoid, necessary for net power.<ref name="PB11">"Advances Towards PB11 Fusion With the Dense Plasma Focus", Eric Lerner, Lawrenceville Plasma Physics, 2008</ref>

In August 2014, MIT announced a tokamak it named the [[Physics:ARC fusion reactor|ARC fusion reactor]], using rare-earth barium-copper oxide (REBCO) superconducting tapes to construct high-magnetic field coils that it claimed produced comparable magnetic field strength in a smaller configuration than other designs.<ref name="auto3">{{cite news|last=Chandler|first=David L.|date=10 August 2015|title=A small, modular, efficient fusion plant|work=MIT News|publisher=MIT News Office|url=http://newsoffice.mit.edu/2015/small-modular-efficient-fusion-plant-0810}}</ref>

In October 2015, researchers at the [[Organization:Max Planck Institute of Plasma Physics|Max Planck Institute of Plasma Physics]] completed building the largest [[Physics:Stellarator|stellarator]] to date, the [[Physics:Wendelstein 7-X|Wendelstein 7-X]]. In December they produced the first helium plasma, and in February 2016 produced hydrogen plasma.<ref name="auto5">{{cite web|title=Wendelstein W7-X starting its experimental journey|url=http://www.ipp.mpg.de/4010154/02_16/w7x|publisher=ipp.mpg.de|location=Germany}}</ref> In 2015, with plasma discharges lasting up to 30 minutes, Wendelstein 7-X attempted to demonstrate the essential stellarator attribute: continuous operation of a high-temperature plasma.<ref>{{cite web|title=NextBigFuture.com - German Nuclear Fusion Stellarator test reactor has been started|url=https://www.nextbigfuture.com/2015/12/german-nuclear-fusion-stellarator-test.html|access-date=14 November 2018|website=NextBigFuture.com}}</ref>

In 2014 EAST achieved a record confinement time of 30 seconds for plasma in the [[Physics:High-confinement mode|high-confinement mode]] (H-mode), thanks to improved heat dispersal. This was an order of magnitude improvement vs other reactors.<ref>{{cite web|date=November 18, 2013|title=Fusion reactor achieves tenfold increase in plasma confinement time|url=https://arstechnica.com/science/2013/11/fusion-reactor-achieves-tenfold-increase-in-plasma-confinement-time/|website=Ars Technica}}</ref> In 2017 the reactor achieved a stable 101.2-second steady-state high confinement plasma, setting a world record in long-pulse H-mode operation.<ref>{{cite web|date=July 6, 2017|title=China's 'artificial sun' sets world record with 100 second steady-state high performance plasma|url=https://phys.org/news/2017-07-china-artificial-sun-world-steady-state.html|publisher=Phys.org}}</ref>

In 2018 MIT scientists formulated a theoretical means to remove the excess heat from compact nuclear fusion reactors via larger and longer [[Physics:Divertor|divertor]]s.<ref>{{Cite web|last=Chandler|first=David L.|date=2018-10-09|title=A new path to solving a longstanding fusion challenge|url=https://news.mit.edu/2018/solving-excess-heat-fusion-power-plants-1009|archive-url=https://web.archive.org/web/20190217203103/https://news.mit.edu/2018/solving-excess-heat-fusion-power-plants-1009|archive-date=2019-02-17|access-date=2019-02-17|website=MIT News}}</ref>

In 2019 the United Kingdom announced a planned £200-million (US$248-million) investment to produce a design for a fusion facility named the [[Physics:Spherical Tokamak for Energy Production|Spherical Tokamak for Energy Production]] (STEP), by the early 2040s.<ref name="auto10">{{Cite web|date=October 22, 2019|title=UK wants to build world's first fusion power plant 20 years from now|url=https://www.zmescience.com/science/uk-wants-to-build-worlds-first-fusion-power-plant-20-years-from-now/}}</ref><ref name="auto6">{{Cite journal|last=Gibney|first=Elizabeth|date=2019-10-11|title=UK hatches plan to build world's first fusion power plant|url=http://www.nature.com/articles/d41586-019-03039-9|journal=Nature|language=en|doi=10.1038/d41586-019-03039-9|pmid=33037417|s2cid=208833905}}</ref>

== 2020s ==
[[File:NIF output over 10 years.png|upright=1.5|thumb|alt=Plot of NIF results from 2012 to 2021|Plot of NIF results from 2012 to 2021 shows a dramatic breakthrough in August 2021 in the performance of ICF on NIF]]

In December 2020, the Chinese experimental nuclear fusion reactor [[Physics:HL-2M|HL-2M]] achieved its first <!--confirmed-->plasma discharge.<ref>{{cite news|title=China turns on nuclear-powered 'artificial sun' (Update)|language=en|work=phys.org|url=https://phys.org/news/2020-12-china-nuclear-powered-artificial-sun.html|access-date=15 January 2021}}</ref> In May 2021, [[Physics:Experimental Advanced Superconducting Tokamak|Experimental Advanced Superconducting Tokamak]] (EAST) announced a new world record for superheated plasma, sustaining a temperature of 120 M°C for 101 seconds and a peak of 160 M°C for 20 seconds.<ref>{{cite news|date=May 29, 2021|title=Chinese 'Artificial Sun' experimental fusion reactor sets world record for superheated plasma time|work=The Nation|url=https://nation.com.pk/29-May-2021/chinese-artificial-sun-experimental-fusion-reactor-sets-world-record-for-superheated-plasma-time|accessdate=May 31, 2021}}</ref> In December 2021 EAST set a new world record for high temperature (70 M°C<ref>{{Cite web|title=China's $1 trillion 'artificial sun' fusion reactor just got five times hotter than the sun|url=https://www.livescience.com/chinas-1-trillion-artificial-sun-fusion-reactor-just-got-five-times-hotter-than-the-sun|access-date=2022-01-10|website=LiveScience|date=6 January 2022 |language=en}}</ref>) plasma of 1,056 seconds.<ref>{{Cite web|title=Chinese artificial sun sets new world record|url=https://www.shine.cn/news/nation/2112310300/|access-date=2021-12-31|website=SHINE|language=en}}</ref>

In 2020, [[Company:Chevron Corporation|Chevron Corporation]] announced an investment in start-up Zap Energy, co-founded by British entrepreneur and investor, Benj Conway, together with physicists Brian Nelson and Uri Shumlak from [[Organization:University of Washington|University of Washington]].<ref name="auto4">{{Cite news |date=2020-08-12|title=Oil major Chevron invests in nuclear fusion startup Zap Energy|language=en|work=Reuters|url=https://www.reuters.com/article/us-chevron-investment-nuclear-idUSKCN25831E|access-date=2020-10-11}}</ref> In 2021 the company raised $27.5 million in Series B funding led by Addition.<ref>{{Cite web|date=May 19, 2021|title=Zap Energy Raises $27.5 Million to Advance Reactor Technology|url=https://www.businesswire.com/news/home/20210519005548/en/Zap-Energy-Raises-27.5-Million-to-Advance-Reactor-Technology|website=www.businesswire.com}}</ref>

In 2021, the US DOE launched the INFUSE program, a public-private knowledge sharing initiative involving a PPPL, [[Physics:MIT Plasma Science and Fusion Center|MIT Plasma Science and Fusion Center]] and Commonwealth Fusion Systems partnership,<ref>{{Cite web|last=Princeton Plasma Physics Laboratory|date=2021-01-02|title=Future Zero-Emissions Power Plants: Scientists Collaborate on Development of Commercial Fusion Energy|url=https://scitechdaily.com/future-zero-emissions-power-plants-scientists-collaborate-on-development-of-commercial-fusion-energy/|access-date=2021-02-08|website=SciTechDaily|language=en-US}}</ref> together with partnerships with TAE Technologies, Princeton Fusion Systems, and Tokamak Energy.<ref>{{Cite news|date=2021-01-26|title=Three new public-private INFUSE projects to speed development of fusion energy selected for PPPL|url=https://www.miragenews.com/three-new-public-private-infuse-projects-to-speed-development-of-fusion-energy-selected-for-pppl/,%20https://www.miragenews.com/three-new-public-private-infuse-projects-to-speed-development-of-fusion-energy-selected-for-pppl|access-date=2021-02-08|newspaper=Mirage News|language=en-AU}}</ref> In 2021, DOE's Fusion Energy Sciences Advisory Committee approved a strategic plan to guide fusion energy and plasma physics research<ref>{{Cite web|title=Nuclear fusion group calls for building a pilot plant by the 2040s|url=https://phys.org/news/2021-01-nuclear-fusion-group-2040s.html|access-date=2021-02-15|website=phys.org|language=en}}</ref><ref>{{Cite web|last=Lawrence Livermore National Laboratory|date=2021-04-19|title=DOE Pushes for Aggressive U.S. Investment in Fusion Energy|url=https://scitechdaily.com/doe-pushes-for-aggressive-u-s-investment-in-fusion-energy/|access-date=2021-05-21|website=SciTechDaily|language=en-US}}</ref><ref>{{Cite web|last1=Cho|first1=Adrian|date=2020-12-08|title=U.S. physicists rally around ambitious plan to build fusion power plant|url=https://www.science.org/content/article/us-physicists-rally-around-ambitious-plan-build-fusion-power-plant|access-date=2021-02-09|website=Science -AAAS|language=en}}</ref> that included a working power plant by 2040, similar to Canadian, Chinese, and U.K. efforts.<ref>{{Cite book|last=|first=|url=https://science.osti.gov/-/media/fes/fesac/pdf/2020/202012/DRAFT_Fusion_and_Plasmas_Report_120420.pdf|title=Powering the Future: Fusion and Plasmas|publisher=United States Department of Energy|year=2021|isbn=|location=Washington, D.C.|pages=}}</ref><ref>{{Cite web|date=2021-01-07|title=DOE Fusion Panel Approves Long-Range Plan|url=https://www.aip.org/fyi/2021/doe-fusion-panel-approves-long-range-plan|access-date=2021-02-08|website=www.aip.org|language=en}}</ref>

In January 2021, SuperOx announced the commercialization of a new superconducting wire, with more than 700 A/mm2 current capability.<ref>{{cite journal|last1=Molodyk|first1=A.|last2=Samoilenkov|first2=S.|last3=Markelov|first3=A.|last4=Degtyarenko|first4=P.|last5=Lee|first5=S.|last6=Petrykin|first6=V.|last7=Gaifullin|first7=M.|last8=Mankevich|first8=A.|last9=Vavilov|first9=A.|last10=Sorbom|first10=B.|last11=Cheng|first11=J.|date=22 January 2021|title=Development and large volume production of extremely high current density YBa 2 Cu 3 O 7 superconducting wires for fusion|journal=Scientific Reports|volume=11|issue=1|pages=2084|doi=10.1038/s41598-021-81559-z|pmc=7822827|pmid=33483553|last15=Gavrilkin|last16=Tsvetkov|last26=Wimbush|first26=S. C.|last27=Strickland|first27=N. M.|last28=Vasiliev|first13=L.|first25=A. E.|last25=Pantoja|last14=Hartwig|last13=Kesler|first12=S.|first24=M.|last12=Garberg|first14=Z.|first15=S.|first28=A.|last22=Larbalestier|first20=A.|first17=T.|last18=Awaji|first18=S.|last19=Abraimov|first19=D.|last24=Bonura|last20=Francis|last21=Bradford|first21=G.|first22=D.|last23=Senatore|first16=A.|first23=C.|last17=Okada}}</ref><ref>{{Cite web|last=Clery|first=Daniel|date=2021-04-08|title=With 'smoke ring' technology, fusion startup marks steady progress|url=https://www.science.org/content/article/smoke-ring-technology-fusion-startup-marks-steady-progress|access-date=2021-04-11|website=Science - AAAS|language=en}}</ref>

TAE Technologies announced that its Norman device had sustained a temperature of about 60 million degrees C for 30 milliseconds, 8 and 10 times higher, respectively, than the company's previous devices. The duration was claimed to be limited by the power supply rather than the device.{{citation needed|date=August 2023}}

In August 2021, the National Ignition Facility recorded a record-breaking 1.3 megajoules of energy created from fusion which is the first example of the [[Physics:Lawson criterion|Lawson criterion]] being surpassed.<ref>{{Cite journal |last1=Indirect Drive ICF Collaboration |last2=Abu-Shawareb |first2=H. |last3=Acree |first3=R. |last4=Adams |first4=P. |last5=Adams |first5=J. |last6=Addis |first6=B. |last7=Aden |first7=R. |last8=Adrian |first8=P. |last9=Afeyan |first9=B. B. |last10=Aggleton |first10=M. |last11=Aghaian |first11=L. |last12=Aguirre |first12=A. |last13=Aikens |first13=D. |last14=Akre |first14=J. |last15=Albert |first15=F. |date=2022-08-08 |title=Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment |url=https://link.aps.org/doi/10.1103/PhysRevLett.129.075001 |journal=Physical Review Letters |volume=129 |issue=7 |pages=075001 |doi=10.1103/PhysRevLett.129.075001|pmid=36018710 |s2cid=250321131 |doi-access=free |hdl=10044/1/99300 |hdl-access=free }}</ref>

In February 2022, JET sustained 11 MW and a Q value of 0.33 for over 5 seconds, outputting 59.7 megajoules, using a mix of deuterium and tritium for fuel.<ref>{{Cite news|title=Major breakthrough on nuclear fusion energy|work=BBC News |date=9 February 2022 |url=https://www.bbc.co.uk/news/science-environment-60312633|access-date=2022-02-09|language=en}}</ref> In March 2022 it was announced that Tokamak Energy achieved a record plasma temperature of 100 million [[Kelvin|kelvin]]s, inside a commercial compact tokamak.<ref>{{Cite web|url=https://interestingengineering.com/innovation/nuclear-fusion-plasma-record|title=A nuclear fusion device pushes plasma to a record-breaking 100 million degrees|first=Chris|last=Young|date=March 11, 2022|website=interestingengineering.com}}</ref>

In December 2022, the NIF achieved the first scientific breakeven controlled fusion experiment, with an energy gain of 1.5.<ref>{{Cite journal |last=Clery |first=Daniel |date=13 December 2022 |title=With historic explosion, a long sought fusion breakthrough |url=https://www.science.org/content/article/historic-explosion-long-sought-fusion-breakthrough |access-date=2022-12-13 |website=Science |language=en |doi=10.1126/science.adg2803}}</ref><ref>{{citation|journal=Physics Today|publisher=American Institute of Physics|title=National Ignition Facility surpasses long-awaited fusion milestone|author=David Kramer|date=December 13, 2022|volume=2022 |issue=2 |pages=1213a |doi=10.1063/PT.6.2.20221213a |bibcode=2022PhT..2022b1213. |s2cid=254663644 |quote=The shot at Lawrence Livermore National Laboratory on 5 December is the first-ever controlled fusion reaction to produce an energy gain.|url=https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/}}</ref>

== References ==

=== Citations ===
{{reflist}}

=== Bibliography ===

* {{Cite book|last1=Cockburn|first1=Stewart|last2=Ellyard|first2=David|url=https://www.worldcat.org/oclc/8666832|title=Oliphant, the life and times of Sir Mark Oliphant|date=1981|publisher=Axiom Books|isbn=0-9594164-0-4|location=Adelaide|oclc=8666832}}
* {{Cite book|last=Dean|first=Stephen O.|chapter-url=http://dx.doi.org/10.1007/978-1-4614-6037-4_15|chapter=The Ultimate Energy Source?|date=2013|title=Search for the Ultimate Energy Source|series=Green Energy and Technology|publisher=Springer New York|isbn=978-1-4614-6036-7|place=New York, NY|pages=233–238|doi=10.1007/978-1-4614-6037-4_15|access-date=2021-06-14}}

== External links ==

* {{Cite web |date=2003-12-16 |title=Science Museum, London - Famous Fusion Experiments |url=http://www.sciencemuseum.org.uk/on-line/fusion/famous.asp |access-date=2022-11-06 |archive-url=https://web.archive.org/web/20031216103922/http://www.sciencemuseum.org.uk/on-line/fusion/famous.asp |archive-date=2003-12-16 }}
* {{Cite journal |last=Burkart |first=Werner |date=2005-09-21 |title=Status report on fusion research |journal=Nuclear Fusion |volume=45 |issue=10A |doi=10.1088/0029-5515/45/10a/e01 |s2cid=250865675 |issn=0029-5515|doi-access=free }}

{{Fusion power}}

{{DEFAULTSORT:Nuclear fusion (history)}}
[[Category:Nuclear fusion]]
[[Category:History of physics]]

{{Sourceattribution|History of nuclear fusion}}