Princeton Plasma Physics Laboratory (PPPL) is a

United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and energy production, the research and development of nuclear power, the military's nuclear w ...

national laboratory for

plasma physics Plasma () is a state of matter characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, mostly in stars (including th ...

and

nuclear fusion Nuclear fusion is a nuclear reaction, reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutrons, neutron by-products. The difference in mass between the reactants and products is manifested as either the rele ...

science. Its primary mission is research into and development of fusion as an energy source. It is known for the development of the

stellarator A stellarator confines Plasma (physics), plasma using external magnets. Scientists aim to use stellarators to generate fusion power. It is one of many types of magnetic confinement fusion devices. The name "stellarator" refers to stars because ...

and

tokamak A tokamak (; ) is a device which uses a powerful magnetic field generated by external magnets to confine plasma (physics), plasma in the shape of an axially symmetrical torus. The tokamak is one of several types of magnetic confinement fusi ...

designs, along with numerous fundamental advances in plasma physics and the exploration of many other plasma confinement concepts. PPPL grew out of the top-secret

Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...

project to control thermonuclear reactions, called Project Matterhorn. The focus of this program changed from

H-bomb A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lowe ...

s to fusion power in 1951, when

Lyman Spitzer Lyman Spitzer Jr. (June 26, 1914 – March 31, 1997) was an American theoretical physicist, astronomer and mountaineer. As a scientist, he carried out research into star formation and plasma physics and in 1946 conceived the idea of telesco ...

developed the stellarator concept and was granted funding from the Atomic Energy Commission to study the concept. This led to a series of machines in the 1950s and 1960s. In 1961, after declassification, Project Matterhorn was renamed the Princeton Plasma Physics Laboratory. PPPL's stellarators proved unable to meet their performance goals. In 1968, Soviet's claims of excellent performance on their tokamaks generated intense scepticism, and to test it, PPPL's

Model C stellarator The Model C stellarator was the first large-scale stellarator to be built, during the early stages of fusion power research. Planned since 1952, construction began in 1961 at what is today the Princeton Plasma Physics Laboratory (PPPL). The Mo ...

was converted to a tokamak. It verified the Soviet claims, and since that time, PPPL has been a worldwide leader in tokamak theory and design, building a series of record-breaking machines including the

Princeton Large Torus The Princeton Large Torus (or PLT), was an early tokamak built at the Princeton Plasma Physics Laboratory (PPPL). It was one of the first large scale tokamak machines and among the most powerful in terms of current and magnetic fields. Originally ...

TFTR The Tokamak Fusion Test Reactor (TFTR) was an experimental tokamak built at Princeton Plasma Physics Laboratory (PPPL) circa 1980 and entering service in 1982. TFTR was designed with the explicit goal of reaching scientific breakeven, the point w ...

and many others. Dozens of smaller machines were also built to test particular problems and solutions, including the ATC, NSTX, and LTX. PPPL is operated by

Princeton University Princeton University is a private university, private Ivy League research university in Princeton, New Jersey, United States. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial ...

on the Forrestal Campus in

Plainsboro Township, New Jersey Plainsboro Township is a Township (New Jersey), township situated in southern Middlesex County, New Jersey, Middlesex County, in the U.S. state of New Jersey. Centrally located in the Raritan River, Raritan Valley region, the township is an ou ...

History

Formation

In 1950, John Wheeler was setting up a secret

research lab at

. Lyman Spitzer, Jr., an avid mountaineer, was aware of this program and suggested the name "Project Matterhorn". Spitzer, a professor of astronomy, had for many years been involved in the study of very hot rarefied gases in interstellar space. While leaving for a ski trip to

Aspen Aspen is a common name for certain tree species in the Populus sect. Populus, of the ''Populus'' (poplar) genus. Species These species are called aspens: * ''Populus adenopoda'' – Chinese aspen (China, south of ''P. tremula'') * ''Populus da ...

in February 1951, his father called and told him to read the front page of the ''

New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...

''. The paper had a story about claims released the day before in

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

that a relatively unknown German scientist named

Ronald Richter Ronald Richter (1909–1991) was an Austrian-born German, later Argentine citizen, scientist who became infamous in connection with the Argentine Huemul Project and the National Atomic Energy Commission (CNEA). The project was intended to gener ...

had achieved nuclear fusion in his Huemul Project. Spitzer ultimately dismissed these claims, and they were later proven erroneous, but the story got him thinking about fusion. While riding the

chairlift An elevated passenger ropeway, or chairlift, is a type of aerial lift, which consists of a continuously circulating steel wire rope loop strung between two end terminals and usually over intermediate towers. They are the primary on-hill tran ...

at Aspen, he struck upon a new concept to confine a plasma for long periods so it could be heated to fusion temperatures. He called this concept the

. Later that year he took this design to the Atomic Energy Commission in Washington. As a result of this meeting and a review of the invention by scientists throughout the nation, the stellarator proposal was funded in 1951. As the device would produce high-energy

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

s, which could be used for breeding weapon fuel, the program was classified and carried out as part of Project Matterhorn. Matterhorn ultimately ended its involvement in the bomb field in 1954, becoming entirely devoted to the fusion power field. In 1958, this magnetic fusion research was declassified following the United Nations International Conference on the Peaceful Uses of Atomic Energy. This generated an influx of graduate students eager to learn the "new" physics, which in turn influenced the lab to concentrate more on basic research. The early figure-8 stellarators included: Model-A, Model-B, Model-B2, Model-B3. Model-B64 was a square with round corners, and Model-B65 had a racetrack configuration. The last and most powerful stellarator at this time was the "racetrack" Model C (operating from 1961 to 1969).

Tokamak

By the mid-1960s it was clear something was fundamentally wrong with the stellarators, as they leaked fuel at rates far beyond what theory predicted, rates that carried away energy from the plasma that was far beyond what the fusion reactions could ever produce. Spitzer became extremely skeptical that fusion energy was possible and expressed this opinion in very public fashion in 1965 at an international meeting in the UK. At the same meeting, the Soviet delegation announced results about 10 times better than any previous device, which Spitzer dismissed as a measurement error. At the next meeting in 1968, the Soviets presented considerable data from their devices that showed even greater performance, about 100 times the

Bohm diffusion The diffusion of plasma across a magnetic field was conjectured to follow the Bohm diffusion scaling as indicated from the early plasma experiments of very lossy machines. This predicted that the rate of diffusion was linear with temperature and in ...

limit. An enormous argument broke out between the AEC and the various labs about whether this was real. When a UK team verified the results in 1969, the AEC suggested PPPL to convert their Model C to a tokamak to test it, as the only lab willing to build one from scratch, Oak Ridge, would need some time to build theirs. Seeing the possibility of being bypassed in the fusion field, PPPL eventually agreed to convert the Model C to what became the Symmetric Tokamak (ST), quickly verifying the approach. Two small machines followed the ST, exploring ways to heat the plasma, and then the

(PLT) to test whether the theory that larger machines would be more stable was true. Starting in 1975, PLT verified these "scaling laws" and then went on to add

neutral beam injection Neutral-beam injection (NBI) is one method used to heat Plasma (physics), plasma inside a Tokamak, fusion device consisting in a beam of high-energy neutral particles that can enter the magnetic confinement field. When these neutral particles are i ...

from Oak Ridge that resulted in a series of record-setting plasma temperatures, eventually topping out at 78 million

kelvin The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By de ...

s, well beyond what was needed for a practical fusion power system. Its success was major news. With this string of successes, PPPL had little trouble winning the bid to build an even larger machine, one specifically designed to reach "breakeven" while running on an actual fusion fuel, rather than a test gas. This produced the

Tokamak Fusion Test Reactor The Tokamak Fusion Test Reactor (TFTR) was an experimental tokamak built at Princeton Plasma Physics Laboratory (PPPL) circa 1980 and entering service in 1982. TFTR was designed with the explicit goal of reaching scientific breakeven, the point w ...

, or TFTR, which was completed in 1982. After a lengthy breaking-in period, TFTR began slowly increasing the temperature and density of the fuel, while introducing

deuterium Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...

gas as the fuel. In April 1986, it demonstrated a combination of density and confinement, the so-called

fusion triple product The Lawson criterion is a figure of merit used in nuclear fusion research. It compares the rate of energy being generated by fusion reactions within the fusion fuel to the rate of energy losses to the environment. When the rate of production is ...

, well beyond what was needed for a practical reactor. In July, it reached a temperature of 200 million kelvins, far beyond what was needed. However, when the system was operated with both of these conditions at the same time, a high enough triple product and temperature, the system became unstable. Three years of effort failed to address these issues, and TFTR never reached its goal. The system continued performing basic studies on these problems until being shut down in 1997.Staff (1996) "Fusion Lab Planning Big Reactor's Last Run", ''

The Record The Record may refer to: Music * The Record (Fear album), ''The Record'' (Fear album), a 1982 studio album by the hardcore-punk band Fear * The Record (Boygenius album), ''The Record'' (Boygenius album), a 2023 studio album by the indie rock supe ...

'', 22 December 1996, p. N-07. Beginning in 1993, TFTR was the first in the world to use 1:1 mixtures of

–

tritium Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the ...

. In 1994 it yielded an unprecedented 10.7 megawatts of fusion power.

Later designs

In 1999, the

National Spherical Torus Experiment The National Spherical Torus Experiment (NSTX) is a magnetic fusion device based on the ''spherical tokamak'' concept. It was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, ...

(NSTX), based on the spherical tokamak concept, came online at the PPPL. Odd-parity heating was demonstrated in the 4 cm radius PFRC-1 experiment in 2006. PFRC-2 has a plasma radius of 8 cm. Studies of electron heating in PFRC-2 reached 500 eV with pulse lengths of 300 ms. In 2015, PPPL completed an upgrade to NSTX to produce NSTX-U that made it the most powerful experimental fusion facility, or tokamak, of its type in the world. In 2017, the group received a Phase II NIAC grant along with two NASA STTRs funding the RF subsystem and superconducting coil subsystem. In 2024, the lab announced MUSE, a new

. MUSE uses rare-earth permanent magnets with a field strength that can exceed 1.2 teslas. The device uses quasiaxisymmetry, a subtype of

quasisymmetry In magnetic confinement fusion, quasisymmetry (sometimes hyphenated as quasi-symmetry) is a type of continuous symmetry in the magnetic field strength of a stellarator. Quasisymmetry is desired, as Noether's theorem implies that there exists a con ...

. The research team claimed that its use of quasisymmetry was more sophisticated than prior devices. Also in 2024, PPL announced a

reinforcement learning Reinforcement learning (RL) is an interdisciplinary area of machine learning and optimal control concerned with how an intelligent agent should take actions in a dynamic environment in order to maximize a reward signal. Reinforcement learnin ...

model that could forecast tearing mode instabilities up to 300 milliseconds in advance. That is enough time for the plasma controller to adjust operating parameters to prevent the tear and maintain

H-mode In plasma physics and magnetic confinement fusion, the high-confinement mode (H-mode) is a phenomenon observed in toroidal fusion plasmas such as tokamaks. In general, plasma energy confinement degrades as the applied heating power is increased. Ab ...

performance.

Directors

The following persons served as the Princeton Plasma Physics Laboratory director: Table notes:

Timeline of major research projects and experiments

DateFormat = yyyy ImageSize = width:1000 height:auto barincrement:25 PlotArea = left:125 right:65 bottom:70 top:15 Colors = id:canvas value:rgb(0.97,0.97,0.97) id:grid1 value:rgb(0.80,0.80,0.80) id:grid2 value:rgb(0.86,0.86,0.86) id:dir value:rgb(0.86,0.86,0.26) id:dir2 value:rgb(0.96,0.96,0.26) id:lightblue value:rgb(0.60,0.99,0.99) id:sphe value:rgb(0.80,0.80,0.99) legend: Spherator id:sphtok value:rgb(0.58,0.90,0.98) legend: Spherical_Tokamak id:stella value:rgb(0.95,0.70,0.70) legend: Stellarator id:tok value:rgb(0.38,0.70,0.88) legend: Tokamak id:other value:rgb(0.38,0.88,0.38) legend: Other Period = from:1950 till:2020 TimeAxis = orientation:horizontal format:yyyy ScaleMajor = unit:year increment:5 start:1950 gridcolor:grid1 ScaleMinor = unit:year increment:1 start:2020 gridcolor:grid2 AlignBars = justify Legend = position:bottom BackgroundColors = canvas:canvas bars:canvas BarData= bar:dir text: Directors barset:fusion bar:fusion1 text: Fusion program bar:fusion2 bar:fusion3 text: Other_fusion_related bar:fusion4 bar:fusion5 bar:fusion6 barset:other PlotData= width:25 fontsize:9 textcolor:black anchor:from align:left color:dir shift:(0,-4) bar:dir from:1951 till:1961 text: " Spitzer" from:1961 till:1980 color: dir2 text: "

Gottlieb Gottlieb (formerly D. Gottlieb & Co.) was an American arcade game corporation based in Chicago, Illinois. It is best known for creating a vast line of pinball machines and arcade games (including ''Q*bert'') throughout much of the 20th century. ...

" from:1981 till:1990 text: "

Fürth Fürth (; East Franconian German, East Franconian: ; ) is a List of cities and towns in Germany, city in northern Bavaria, Germany, in the administrative division (''Regierungsbezirk'') of Middle Franconia. It is the Franconia#Towns and cities, s ...

" from:1991 till:1996 color: dir2 text: " Davidson" from:1997 till:2008 text: " Goldston" from:2008 till:2016 color: dir2 text: "Prager" from:2018 till:end text: " Cowley" width:25 fontsize:10 textcolor:black anchor:from align:left color:tok bar:fusion1 from:1953 till:1962 shift:(0,-4) color:stella text: "Model A/B stellarators" bar:fusion2 from:1962 till:1969 shift:(0,-4) color:stella text: "

" bar:fusion1 from:1970 till:1974 shift:(0,-4) color:tok text: "Symmetric Tokamak" bar:fusion2 from:1975 till:1986 shift:(0,-4) color:tok text: "

" bar:fusion1 from:1982 till:1997 shift:(0,-4) color:tok text: "

" bar:fusion1 from:1999 till:end shift:(0,-4) color:sphtok text: "

" width:25 fontsize:10 textcolor:black anchor:from align:left color:other barset:other bar:fusion3 from:1971 till:1976 shift:(0,-4) color:sphe text: "Floating Multipole-1" bar:fusion4 from:1972 till:1976 shift:(0,-4) color:tok text: "Adiabatic Toroidal Compressor" bar:fusion5 from:1978 till:1983 shift:(0,-4) text: "Poloidal Divertor Experiment" bar:fusion6 from:1984 till:1992 shift:(0,-4) text: "Princeton Beta Experiment" bar:fusion3 from:2005 till:2008 shift:(0,-4) color:sphtok text: "Current Drive Experiment" bar:fusion4 from:2008 till:end shift:(0,-4) color:sphtok text: "

Lithium Tokamak Experiment The Lithium Tokamak Experiment (LTX), and its predecessor, the Current Drive Experiment-Upgrade (CDX-U), are devices dedicated to the study of liquid lithium as a plasma-facing component (PFC) at Princeton Plasma Physics Laboratory. Benefits of ...

" bar:fusion5 from:1995 till:end shift:(0,-4) text: "Magnetic Reconnection Experiment" bar:fusion6 from:1999 till:end shift:(0,-4) text: "Hall Thruster Experiment" from:2008 till:end shift:(0,-4) text: " Field Reversed Configuration"

Other domestic and international research activities

Laboratory scientists are collaborating with researchers on fusion science and technology at other facilities, including

DIII-D DIII-D is a tokamak that has been operated since the late 1980s by General Atomics (GA) in San Diego, California, for the United States Department of Energy. The DIII-D National Fusion Facility is part of the ongoing effort to achieve magnetica ...

in San Diego,

EAST East is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fact that ea ...

in China, JET in the United Kingdom,

KSTAR The KSTAR (or Korea Superconducting Tokamak Advanced Research; , literally "superconductive nuclear fusion research device") is a magnetic fusion device at the Korea Institute of Fusion Energy in Daejeon, South Korea. It is intended to study ...

in South Korea, the LHD in Japan, the

Wendelstein 7-X The Wendelstein 7-X (abbreviated W7-X) reactor is an experimental stellarator built in Greifswald, Germany, by the Max Planck Institute for Plasma Physics (IPP), and completed in October 2015.International Thermonuclear Experimental Reactor ITER (initially the International Thermonuclear Experimental Reactor, ''iter'' meaning "the way" or "the path" in Latin) is an international nuclear fusion research and engineering megaproject aimed at creating energy through a fusion process s ...

(ITER) in France. PPPL manages the U.S. ITER project activities together with

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a federally funded research and development centers, federally funded research and development center in Oak Ridge, Tennessee, United States. Founded in 1943, the laboratory is sponsored by the United Sta ...

and

Savannah River National Laboratory The Savannah River National Laboratory (SRNL) is a multi-program United States Department of Energy national laboratories, national laboratory for the U.S. United States Department of Energy, Department of Energy’s (DOE) Office of Environment ...

. The lab delivered 75% of components for the fusion energy experiment's electrical network in 2017 and has been leading the design and construction of six diagnostic tools for analyzing ITER plasmas. The PPPL physicist Richard Hawryluk served as ITER Deputy Director-General from 2011 to 2013. In 2022, PPPL staff developed with researchers from other national labs and universities over several months a US ITER research plan during the joint Fusion Energy Sciences Research Needs Workshop. Staff are applying knowledge gained in fusion research to a number of theoretical and experimental areas including

materials science Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials sci ...

solar physics Solar physics is the branch of astrophysics that specializes in the study of the Sun. It intersects with many disciplines of pure physics and astrophysics. Because the Sun is uniquely situated for close-range observing (other stars cannot be re ...

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

, and

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary sector of the economy. The term may refer ...

. PPPL also aims to speed the development of fusion energy through the development of an increased number of public-private partnerships.

Plasma science and technology

* Beam Dynamics and Nonneutral Plasma * Laboratory for Plasma Nanosynthesis (LPN)"Laboratory for Plasma Nanosynthesis (LPN)"
Princeton Plasma Physics Laboratory, accessed 16 May 2018.

Theoretical plasma physics

* DOE Scientific Simulation Initiative * U.S. MHD Working Group * Field Reversed Configuration (FRC) Theory Consortium * Tokamak Physics Design and Analysis Codes * TRANSP Code * National Transport Code Collaboration (NTCC) Modules Library

Transportation

Tiger Transit's Route 3 runs to Forrestal Campus and terminates at PPPL.

References

External links

*
Project Matterhorn Publications and Reports, 1951–1958
Princeton University Library Digital Collections * {{Authority control Plainsboro Township, New Jersey Princeton University United States Department of Energy national laboratories Federally Funded Research and Development Centers 1961 establishments in New Jersey Research institutes in New Jersey