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142-581: 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. Its purpose is to advance stellarator technology: though this experimental reactor will not produce electricity, it is used to evaluate the main components of a future fusion power plant; it

284-406: A divertor , which removed impurities from the plasma, greatly reducing the x-ray cooling effect seen on earlier machines. B-64 included straight sections in the curved ends which gave it a squared-off appearance. This appearance led to its name, it was a "figure-8, squared", or 8 squared, or 64. This led to experiments in 1956 where the machine was re-assembled without the twist in the tubes, allowing

426-405: A q around 1 ⁄ 3 , while experiments on tokamaks demonstrated it needs to be at least 1. Machines following this rule showed dramatically improved performance. However, by the mid-1980s the easy path to fusion disappeared; as the amount of current in the new machines began to increase, a new set of instabilities in the plasma appeared. These could be addressed, but only by greatly increasing

568-429: A 'celestial agent' prevented the vacuum arising. Jean Buridan reported in the 14th century that teams of ten horses could not pull open bellows when the port was sealed. The 17th century saw the first attempts to quantify measurements of partial vacuum. Evangelista Torricelli 's mercury barometer of 1643 and Blaise Pascal 's experiments both demonstrated a partial vacuum. In 1654, Otto von Guericke invented

710-447: A C model, which would attempt to actually create fusion reactions at a large scale. This entire series was expected to take about a decade. Around the same time, Jim Tuck had been introduced to the pinch concept while working at Clarendon Laboratory at Oxford University . He was offered a job in the US and eventually ended up at Los Alamos, where he acquainted the other researchers with

852-639: A Munich-based spin-off from the Max Planck Institute for Plasma Physics, which steered the W7-X experiment. Heating a gas increases the energy of the particles within it, so by heating a gas into hundreds of millions of degrees, the majority of the particles within it reach the energy required to fuse. According to the Maxwell–Boltzmann distribution , some of the particles will reach the required energies at much lower average temperatures. Because

994-419: A bulk temperature of about 50 million Celsius, still very hot but within the range of existing experimental systems. The key problem was confining such a plasma; no material container could withstand those temperatures. But because plasmas are electrically conductive, they are subject to electric and magnetic fields which provide a number of solutions. In a magnetic field, the electrons and nuclei of

1136-454: A few hydrogen atoms per cubic meter on average in intergalactic space. Vacuum has been a frequent topic of philosophical debate since ancient Greek times, but was not studied empirically until the 17th century. Clemens Timpler (1605) philosophized about the experimental possibility of producing a vacuum in small tubes. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as

1278-418: A gas-like state of matter known as plasma . According to the ideal gas law , like any hot gas, plasma has an internal pressure and thus wants to expand. For a fusion reactor, the challenge is to keep the plasma contained. In a magnetic field, the electrons and nuclei orbit around the magnetic field lines, confining them to the area defined by the field. A simple confinement system can be made by placing

1420-416: A geometrically based alternative theory of atomism, without the problematic nothing–everything dichotomy of void and atom. Although Descartes agreed with the contemporary position, that a vacuum does not occur in nature, the success of his namesake coordinate system and more implicitly, the spatial–corporeal component of his metaphysics would come to define the philosophically modern notion of empty space as

1562-416: A heat insulating cladding with a diameter of 16 metres, called the cryostat. A cooling device produces enough liquid helium to cool down the magnets and their enclosure (about 425 metric tons of "cold mass") to superconductivity temperature (4 K). The coils will carry 12.8 kA current and create a field of up to 3  teslas . The plasma vessel, built of 20 parts, is on the inside adjusted to

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1704-432: A mass spectrometer must be used in conjunction with the ionization gauge for accurate measurement. Vacuum is useful in a variety of processes and devices. Its first widespread use was in the incandescent light bulb to protect the filament from chemical degradation. The chemical inertness produced by a vacuum is also useful for electron beam welding , cold welding , vacuum packing and vacuum frying . Ultra-high vacuum

1846-479: A measurable vacuum relative to the local environment. Similarly, much higher than normal relative vacuum readings are possible deep in the Earth's ocean. A submarine maintaining an internal pressure of 1 atmosphere submerged to a depth of 10 atmospheres (98 metres; a 9.8-metre column of seawater has the equivalent weight of 1 atm) is effectively a vacuum chamber keeping out the crushing exterior water pressures, though

1988-645: A much greater emphasis on the theoretical understanding of the plasma. In 1961, Melvin B. Gottlieb took over the Matterhorn Project from Spitzer, and on 1 February the project was renamed as the Princeton Plasma Physics Laboratory (PPPL). Continual modification and experimentation on the Model C slowly improved its operation, and the confinement times eventually increased to match that of Bohm predictions. New versions of

2130-434: A naturally occurring partial vacuum, the heavens were originally thought to be seamlessly filled by a rigid indestructible material called aether . Borrowing somewhat from the pneuma of Stoic physics , aether came to be regarded as the rarefied air from which it took its name, (see Aether (mythology) ). Early theories of light posited a ubiquitous terrestrial and celestial medium through which light propagated. Additionally,

2272-631: A new department for all of these projects, becoming "Project Sherwood". With the funding from the AEC, Spitzer began work by inviting James Van Allen to join the group and set up an experimental program. Allen suggested starting with a small "tabletop" device. This led to the Model A design, which began construction in 1952. It was made from 5-centimetre (2.0 in) pyrex tubes about 350 cm (11.5 ft) in total length, and magnets capable of about 1,000 gauss. The machine began operations in early 1953 and clearly demonstrated improved confinement over

2414-496: A new joint research center in plasma physics, to include research on W7-X. The end of the construction phase, which required more than 1 million assembly hours, was officially marked by an inauguration ceremony on 20 May 2014. After a period of vessel leak-checking, beginning in the summer of 2014, the cryostat was evacuated , and magnet testing was completed in July 2015. Operational phase 1 (OP1.1) began 10 December 2015. On that day

2556-525: A problem that came to be known as " pump out ". This effect was causing plasma drift rates that were not only higher than classical theory suggested but also much higher than the Bohm rates. B-3's drift rate was a full three times that of the worst-case Bohm predictions, and failed to maintain confinement for more than a few tens of microseconds. As early as 1954, as research continued on the B-series machines,

2698-426: A proposed propulsion system for interplanetary travel . All of the observable universe is filled with large numbers of photons , the so-called cosmic background radiation , and quite likely a correspondingly large number of neutrinos . The current temperature of this radiation is about 3  K (−270.15  °C ; −454.27  °F ). The quality of a vacuum is indicated by the amount of matter remaining in

2840-460: A quantified extension of volume. By the ancient definition however, directional information and magnitude were conceptually distinct. Medieval thought experiments into the idea of a vacuum considered whether a vacuum was present, if only for an instant, between two flat plates when they were rapidly separated. There was much discussion of whether the air moved in quickly enough as the plates were separated, or, as Walter Burley postulated, whether

2982-482: A result of his theories of atmospheric pressure. A Torricellian vacuum is created by filling with mercury a tall glass container closed at one end, and then inverting it in a bowl to contain the mercury (see below). Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes , and a wide array of vacuum technologies has since become available. The development of human spaceflight has raised interest in

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3124-409: A second heating system known as magnetic pumping. This machine was also modified to add an ultra-high vacuum system. Unfortunately, B-2 demonstrated little heating from the magnetic pumping, which was not entirely unexpected because this mechanism required longer confinement times, and this was not being achieved. As it appeared that little could be learned from this system in its current form, in 1958 it

3266-410: A secret research lab at Princeton University that would carry on theoretical work on H-bombs after he returned to the university in 1951. Spitzer was invited to join this program, given his previous research in interstellar plasmas. But by the time of his trip to Aspen, Spitzer had lost interest in bomb design, and upon his return, he turned his attention full-time to fusion as a power source. Over

3408-415: A temperature of about a billion kelvins . Due to the Maxwell–Boltzmann statistics , a bulk gas at a much lower temperature will still contain some particles at these much higher energies. Because the fusion reactions release so much energy, even a small number of these reactions can release enough energy to keep the gas at the required temperature. In 1944, Enrico Fermi demonstrated that this would occur at

3550-421: A thing as a vacuum can exist. Ancient Greek philosophers debated the existence of a vacuum, or void, in the context of atomism , which posited void and atom as the fundamental explanatory elements of physics. Lucretius argued for the existence of vacuum in the first century BC and Hero of Alexandria tried unsuccessfully to create an artificial vacuum in the first century AD. Following Plato , however, even

3692-532: A toroidal tube. The configuration is characterized by a 'rotational transform', such that a single line of magnetic force, followed around the system, intersects a cross-sectional plane in points which successively rotate about the magnetic axis. ... A rotational transform may be generated either by a solenoidal field in a twisted, or figure-eight shaped, tube, or by the use of an additional transverse multipolar helical field, with helical symmetry. While working at Los Alamos in 1950, John Wheeler suggested setting up

3834-418: A tube inside the open core of a solenoid . The tube can be evacuated and then filled with the requisite gas and heated until it becomes a plasma. The plasma naturally wants to expand outwards to the walls of the tube, as well as move along it, towards the ends. The solenoid creates magnetic field lines running down the center of the tube, and the plasma particles orbit these lines, preventing their motion towards

3976-401: A typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. But higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10 ) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm . Outer space is an even higher-quality vacuum, with the equivalent of just

4118-430: A vacuum is called outgassing . All materials, solid or liquid, have a small vapour pressure , and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. Outgassing has the same effect as a leak and will limit the achievable vacuum. Outgassing products may condense on nearby colder surfaces, which can be troublesome if they obscure optical instruments or react with other materials. This

4260-411: A void. In his Physics , book IV, Aristotle offered numerous arguments against the void: for example, that motion through a medium which offered no impediment could continue ad infinitum , there being no reason that something would come to rest anywhere in particular. In the medieval Muslim world , the physicist and Islamic scholar Al-Farabi wrote a treatise rejecting the existence of the vacuum in

4402-516: Is a non-SI unit): Vacuum is measured in units of pressure , typically as a subtraction relative to ambient atmospheric pressure on Earth. But the amount of relative measurable vacuum varies with local conditions. On the surface of Venus , where ground-level atmospheric pressure is much higher than on Earth, much higher relative vacuum readings would be possible. On the surface of the Moon with almost no atmosphere, it would be extremely difficult to create

Wendelstein 7-X - Misplaced Pages Continue

4544-485: Is a spatial location and t is time. In quantum mechanics and quantum field theory , the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space ). In quantum electrodynamics this vacuum is referred to as ' QED vacuum ' to distinguish it from the vacuum of quantum chromodynamics , denoted as QCD vacuum . QED vacuum

4686-482: Is a state with no matter particles (hence the name), and no photons . As described above, this state is impossible to achieve experimentally. (Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the blackbody photons .) Nonetheless, it provides a good model for realizable vacuum, and agrees with a number of experimental observations as described next. QED vacuum has interesting and complex properties. In QED vacuum,

4828-534: Is an independent partner project of the Max-Planck Institute for Plasma Physics with the University of Greifswald . The Wendelstein 7-X device is based on a five-field-period Helias configuration . It is mainly a toroid , consisting of 50 non-planar and 20 planar superconducting magnetic coils , 3.5 m high, which induce a magnetic field that prevents the plasma from colliding with

4970-538: Is connected to the region of interest. Any fluid can be used, but mercury is preferred for its high density and low vapour pressure. Simple hydrostatic gauges can measure pressures ranging from 1 torr (100 Pa) to above atmospheric. An important variation is the McLeod gauge which isolates a known volume of vacuum and compresses it to multiply the height variation of the liquid column. The McLeod gauge can measure vacuums as high as 10  torr (0.1 mPa), which

5112-434: Is equal to the displacement of a millimeter of mercury ( mmHg ) in a manometer with 1 torr equaling 133.3223684 pascals above absolute zero pressure. Vacuum is often also measured on the barometric scale or as a percentage of atmospheric pressure in bars or atmospheres . Low vacuum is often measured in millimeters of mercury (mmHg) or pascals (Pa) below standard atmospheric pressure. "Below atmospheric" means that

5254-573: Is not used. High vacuum systems must be clean and free of organic matter to minimize outgassing. Ultra-high vacuum systems are usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials and boil them off. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures and minimize residual outgassing during actual operation. Some systems are cooled well below room temperature by liquid nitrogen to shut down residual outgassing and simultaneously cryopump

5396-419: Is of great concern to space missions, where an obscured telescope or solar cell can ruin an expensive mission. The most prevalent outgassing product in vacuum systems is water absorbed by chamber materials. It can be reduced by desiccating or baking the chamber, and removing absorbent materials. Outgassed water can condense in the oil of rotary vane pumps and reduce their net speed drastically if gas ballasting

5538-456: Is one of many types of magnetic confinement fusion devices, most commonly tokamak . The name "stellarator" refers to stars because fusion mostly occurs in stars such as the Sun . It is one of the earliest human-designed fusion power devices. The stellarator was invented by American scientist Lyman Spitzer in 1951. Much of its early development was carried out by Spitzer's team at what became

5680-454: Is the lowest direct measurement of pressure that is possible with current technology. Other vacuum gauges can measure lower pressures, but only indirectly by measurement of other pressure-controlled properties. These indirect measurements must be calibrated via a direct measurement, most commonly a McLeod gauge. The kenotometer is a particular type of hydrostatic gauge, typically used in power plants using steam turbines. The kenotometer measures

5822-543: Is to gradually increase power and duration for up to 30 minutes of continuous plasma discharge, thus demonstrating an essential feature of a future fusion power plant: continuous operation. The name of the project, referring to the mountain Wendelstein in Bavaria, was decided at the end of the 1950s, referencing the preceding project from Princeton University under the name Project Matterhorn . The research facility

Wendelstein 7-X - Misplaced Pages Continue

5964-443: Is used in the study of atomically clean substrates, as only a very good vacuum preserves atomic-scale clean surfaces for a reasonably long time (on the order of minutes to days). High to ultra-high vacuum removes the obstruction of air, allowing particle beams to deposit or remove materials without contamination. This is the principle behind chemical vapor deposition , physical vapor deposition , and dry etching which are essential to

6106-412: Is useful for flywheel energy storage and ultracentrifuges . Vacuums are commonly used to produce suction , which has an even wider variety of applications. The Newcomen steam engine used vacuum instead of pressure to drive a piston. In the 19th century, vacuum was used for traction on Isambard Kingdom Brunel 's experimental atmospheric railway . Vacuum brakes were once widely used on trains in

6248-475: The Heading Indicator (HI) ) are typically vacuum-powered, as protection against loss of all (electrically powered) instruments, since early aircraft often did not have electrical systems, and since there are two readily available sources of vacuum on a moving aircraft, the engine and an external venturi. Vacuum induction melting uses electromagnetic induction within a vacuum. Maintaining a vacuum in

6390-503: The Lamb shift . Coulomb's law and the electric potential in vacuum near an electric charge are modified. Theoretically, in QCD multiple vacuum states can coexist. The starting and ending of cosmological inflation is thought to have arisen from transitions between different vacuum states. For theories obtained by quantization of a classical theory, each stationary point of the energy in

6532-415: The Princeton Plasma Physics Laboratory (PPPL). Spitzer's Model A began operation in 1953 and demonstrated plasma confinement. Larger models followed, but demonstrated poor performance, losing plasma at rates far worse than theoretical predictions. By the early 1960s, hopes of producing a commercial machine faded, and attention turned to studying fundamental theory. By the mid-1960s, Spitzer was convinced that

6674-405: The Sun and the dynamic pressure of the solar winds , so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather . Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre. But although it meets

6816-522: The United States Atomic Energy Commission (AEC) for funding to develop the system. He outlined a plan involving three stages. The first would see the construction of a Model A, whose purpose was to demonstrate that a plasma could be created and that its confinement time was better than a torus . If the A model was successful, the B model would attempt to heat the plasma to fusion temperatures. This would be followed by

6958-431: The condenser is an important aspect of the efficient operation of steam turbines . A steam jet ejector or liquid ring vacuum pump is used for this purpose. The typical vacuum maintained in the condenser steam space at the exhaust of the turbine (also called condenser backpressure) is in the range 5 to 15 kPa (absolute), depending on the type of condenser and the ambient conditions. Evaporation and sublimation into

7100-541: The configuration space gives rise to a single vacuum. String theory is believed to have a huge number of vacua – the so-called string theory landscape . Outer space has very low density and pressure, and is the closest physical approximation of a perfect vacuum. But no vacuum is truly perfect, not even in interstellar space, where there are still a few hydrogen atoms per cubic meter. Stars, planets, and moons keep their atmospheres by gravitational attraction, and as such, atmospheres have no clearly delineated boundary:

7242-469: The vacuum of free space , or sometimes just free space or perfect vacuum , is a standard reference medium for electromagnetic effects. Some authors refer to this reference medium as classical vacuum , a terminology intended to separate this concept from QED vacuum or QCD vacuum , where vacuum fluctuations can produce transient virtual particle densities and a relative permittivity and relative permeability that are not identically unity. In

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7384-574: The (uncooled) divertor. In June 2018 a record ion temperature of about 40 million degrees, a density of 0.8 × 10 particles/m, and a confinement time of 0.2 second yielded a record fusion product of 6 × 10 degree-seconds per cubic metre. During the last experiments of 2018, the density reached 2 × 10 particles/m at a temperature of 20 million degrees. With good plasma values, long-lasting plasmas with long discharge times of 100 seconds were obtained. Energy content exceeded 1 megajoule. In 2021 an analysis of X-ray imaging crystal spectrometer data collected in

7526-484: The 1 atm inside the submarine would not normally be considered a vacuum. Therefore, to properly understand the following discussions of vacuum measurement, it is important that the reader assumes the relative measurements are being done on Earth at sea level, at exactly 1 atmosphere of ambient atmospheric pressure. The SI unit of pressure is the pascal (symbol Pa), but vacuum is often measured in torrs , named for an Italian physicist Torricelli (1608–1647). A torr

7668-461: The 10th century. He concluded that air's volume can expand to fill available space, and therefore the concept of a perfect vacuum was incoherent. According to Ahmad Dallal , Abū Rayhān al-Bīrūnī states that "there is no observable evidence that rules out the possibility of vacuum". The suction pump was described by Arab engineer Al-Jazari in the 13th century, and later appeared in Europe from

7810-483: The 15th century. European scholars such as Roger Bacon , Blasius of Parma and Walter Burley in the 13th and 14th century focused considerable attention on issues concerning the concept of a vacuum. The commonly held view that nature abhorred a vacuum was called horror vacui . There was even speculation that even God could not create a vacuum if he wanted and the 1277 Paris condemnations of Bishop Étienne Tempier , which required there to be no restrictions on

7952-463: The 2018 experiment substantially reduced troubling neoclassical transport heat loss. Collisions between heated particles cause some to escape the magnetic field. This was due to magnetic field cage optimization that was essential in achieving the record results. Financial support for the project is about 80% from Germany and about 20% from the European Union. 90% of German funding comes from

8094-520: The B-1 was that during the heating process, the particles would remain confined for only a few tenths of a millisecond, while once the field was turned off, any remaining particles were confined for as long as 10 milliseconds. This appeared to be due to "cooperative effects" within the plasma. Meanwhile, a second machine known as B-2 was being built. This was similar to the B-1 machine but used pulsed power to allow it to reach higher magnetic energy and included

8236-404: The B-1, which used ohmic heating (see below) to reach plasma temperatures around 100,000 degrees. This machine demonstrated that impurities in the plasma caused large x-ray emissions that rapidly cooled the plasma. In 1956, B-1 was rebuilt with an ultra-high vacuum system to reduce the impurities but found that even at smaller quantities they were still a serious problem. Another effect noticed in

8378-671: The Chilean border. Known as the Huemul Project , this was completed in 1951. Richter soon convinced himself fusion had been achieved in spite of other people working on the project disagreeing. The "success" was announced by Perón on 24 March 1951, becoming the topic of newspaper stories around the world. While preparing for a ski trip to Aspen, Lyman Spitzer received a telephone call from his father, who mentioned an article on Huemul in The New York Times . Looking over

8520-536: The MFP of room temperature air is roughly 100 mm, which is on the order of everyday objects such as vacuum tubes . The Crookes radiometer turns when the MFP is larger than the size of the vanes. Vacuum quality is subdivided into ranges according to the technology required to achieve it or measure it. These ranges were defined in ISO 3529-1:2019 as shown in the following table (100 Pa corresponds to 0.75 Torr; Torr

8662-452: The UK but, except on heritage railways , they have been replaced by air brakes . Manifold vacuum can be used to drive accessories on automobiles . The best known application is the vacuum servo , used to provide power assistance for the brakes . Obsolete applications include vacuum-driven windscreen wipers and Autovac fuel pumps. Some aircraft instruments ( Attitude Indicator (AI) and

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8804-530: The UK reports, Princeton found itself in the position of trying to defend the stellarator as a useful experimental machine while other groups from around the US were clamoring for funds to build tokamaks. In July 1969 Gottlieb had a change of heart, offering to convert the Model C to a tokamak layout. In December it was shut down and reopened in May as the Symmetric Tokamak (ST). The ST immediately matched

8946-424: The absolute pressure is equal to the current atmospheric pressure. In other words, most low vacuum gauges that read, for example 50.79 Torr. Many inexpensive low vacuum gauges have a margin of error and may report a vacuum of 0 Torr but in practice this generally requires a two-stage rotary vane or other medium type of vacuum pump to go much beyond (lower than) 1 torr. Many devices are used to measure

9088-506: The abstract concept of a featureless void faced considerable skepticism: it could not be apprehended by the senses, it could not, itself, provide additional explanatory power beyond the physical volume with which it was commensurate and, by definition, it was quite literally nothing at all, which cannot rightly be said to exist. Aristotle believed that no void could occur naturally, because the denser surrounding material continuum would immediately fill any incipient rarity that might give rise to

9230-418: The center into one of the half-tori, exit into the center of the next tube, and so on. This particle will complete a loop around the entire reactor without leaving the center. Now consider another particle traveling parallel to the first, but initially located near the inside wall of the tube. In this case, it will enter the outside edge of the half-torus and begin to drift down. It exits that section and enters

9372-435: The complex shape of the magnetic field. It has 254 ports (holes) for plasma heating and observation diagnostics. The whole plant is built of five nearly identical modules, which were assembled in the experiment hall. The heating system includes high power gyrotrons for electron cyclotron resonance heating (ECRH), which will deliver up to 15 MW of heating to the plasma. For operational phase 2 (OP-2), after completion of

9514-494: The components of the stress–energy tensor are zero. This means that this region is devoid of energy and momentum, and by consequence, it must be empty of particles and other physical fields (such as electromagnetism) that contain energy and momentum. In general relativity , a vanishing stress–energy tensor implies, through Einstein field equations , the vanishing of all the components of the Ricci tensor . Vacuum does not mean that

9656-435: The concept informed Isaac Newton 's explanations of both refraction and of radiant heat. 19th century experiments into this luminiferous aether attempted to detect a minute drag on the Earth's orbit. While the Earth does, in fact, move through a relatively dense medium in comparison to that of interstellar space, the drag is so minuscule that it could not be detected. In 1912, astronomer Henry Pickering commented: "While

9798-406: The concept. When he heard Spitzer was promoting the stellarator, he also travelled to Washington to propose building a pinch device. He considered Spitzer's plans "incredibly ambitious." Nevertheless, Spitzer was successful in gaining $ 50,000 in funding from the AEC, while Tuck received nothing. The Princeton program was officially created on 1 July 1951. Spitzer, an avid mountain climber, proposed

9940-410: The critical threshold of breakeven would be reached in the early 1980s. What was needed was larger machines and more powerful systems to heat the plasma to fusion temperatures. Tokamaks are a type of pinch machine, differing from earlier designs primarily in the amount of current in the plasma: above a certain threshold known as the safety factor , or q , the plasma is much more stable. ZETA ran at

10082-475: The curvature of space-time is necessarily flat: the gravitational field can still produce curvature in a vacuum in the form of tidal forces and gravitational waves (technically, these phenomena are the components of the Weyl tensor ). The black hole (with zero electric charge) is an elegant example of a region completely "filled" with vacuum, but still showing a strong curvature. In classical electromagnetism ,

10224-523: The definition of outer space, the atmospheric density within the first few hundred kilometers above the Kármán line is still sufficient to produce significant drag on satellites . Most artificial satellites operate in this region called low Earth orbit and must fire their engines every couple of weeks or a few times a year (depending on solar activity). The drag here is low enough that it could theoretically be overcome by radiation pressure on solar sails ,

10366-456: The density of atmospheric gas simply decreases with distance from the object. The Earth's atmospheric pressure drops to about 32 millipascals (4.6 × 10  psi) at 100 kilometres (62 mi) of altitude, the Kármán line , which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from

10508-418: The description in the article, Spitzer concluded it could not possibly work; the system simply could not provide enough energy to heat the fuel to fusion temperatures. But the idea stuck with him, and he began considering systems that would work. While riding the ski lift , he hit upon the stellarator concept. The basic concept was a way to modify the torus layout so that it addressed Fermi's concerns through

10650-407: The design did not lie flat, the tori at either end had to be tilted. This meant the drift cancellation was further reduced, but again, calculations suggested the system would work. To understand how the system works to counteract drift, consider the path of a single particle in the system starting in one of the straight sections. If that particle is perfectly centered in the tube, it will travel down

10792-459: The design of the Model C device was becoming more defined. It emerged as a large racetrack-layout machine with multiple heating sources and a divertor, essentially an even larger B-66. Construction began in 1958 and was completed in 1961. It could be adjusted to allow a plasma minor axis between 5 and 7.5 centimetres (2.0 and 3.0 in) and was 1,200 cm (470 in) in length. The toroidal field coils normally operated at 35,000 gauss. By

10934-410: The device would essentially be cut in half to produce two half-tori. They would then be joined with two straight sections between the open ends. The key was that they were connected to alternate ends so that the right half of one of the tori was connected to the left of the other. The resulting design resembled a figure-8 when viewed from above. Because the straight tubes could not pass through each other,

11076-438: The device's geometry. By twisting one end of the torus compared to the other, forming a figure-8 layout instead of a circle, the magnetic lines no longer travelled around the tube at a constant radius, instead they moved closer and further from the torus' center. A particle orbiting these lines would find itself constantly moving in and out across the minor axis of the torus. The drift upward while it travelled through one section of

11218-427: The electric and magnetic fields have zero average values, but their variances are not zero. As a result, QED vacuum contains vacuum fluctuations ( virtual particles that hop into and out of existence), and a finite energy called vacuum energy . Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. Some experimentally verified effects of vacuum fluctuations include spontaneous emission and

11360-559: The electron and ion temperature, as well as the profiles of important plasma impurities and of the radial electric field resulting from electron and ion particle transport. The German funding arrangement for the project was negotiated in 1994, establishing the Greifswald Branch Institute of the IPP in the north-eastern corner of the recently integrated East Germany . Its new building was completed in 2000. Construction of

11502-480: The energy released by the fusion reaction is much greater than what it takes to start it, even a small number of reactions can heat surrounding fuel until it fuses as well. In 1944, Enrico Fermi calculated the D-T reaction would be self-sustaining at about 50,000,000 degrees Celsius (90,000,000 degrees Fahrenheit). Materials heated beyond a few tens of thousand degrees ionize into their electrons and nuclei , producing

11644-435: The existence of the positron , confirmed two years later. Werner Heisenberg 's uncertainty principle , formulated in 1927, predicted a fundamental limit within which instantaneous position and momentum , or energy and time can be measured. This far reaching consequences also threatened whether the "emptiness" of space between particles exists. The strictest criterion to define a vacuum is a region of space and time where all

11786-701: The fabrication of semiconductors and optical coatings , and to surface science . The reduction of convection provides the thermal insulation of thermos bottles . Deep vacuum lowers the boiling point of liquids and promotes low temperature outgassing which is used in freeze drying , adhesive preparation, distillation , metallurgy , and process purging. The electrical properties of vacuum make electron microscopes and vacuum tubes possible, including cathode-ray tubes . Vacuum interrupters are used in electrical switchgear. Vacuum arc processes are industrially important for production of certain grades of steel or high purity materials. The elimination of air friction

11928-415: The federal government and 10% from the state government of Mecklenburg-Vorpommern . The total investment for the stellarator itself over 1997–2014 amounted to €370 million, while the total cost for the IPP site in Greifswald including investment plus operating costs (personnel and material resources) amounted to €1.06 billion for that 18-year period. This exceeded the original budget estimate, mainly because

12070-400: The first vacuum pump and conducted his famous Magdeburg hemispheres experiment, showing that, owing to atmospheric pressure outside the hemispheres, teams of horses could not separate two hemispheres from which the air had been partially evacuated. Robert Boyle improved Guericke's design and with the help of Robert Hooke further developed vacuum pump technology. Thereafter, research into

12212-478: The first to achieve fusion on Earth, using a particle accelerator to shoot deuterium nuclei into a metal foil containing deuterium , lithium or other elements. These experiments allowed them to measure the nuclear cross section of various reactions of fusion between nuclei, and determined that the tritium-deuterium reaction occurred at a lower energy than any other fuel, peaking at about 100,000  electronvolts (100 keV). 100 keV corresponds to

12354-432: The flexure of the diaphragm, which results in a change in capacitance. These gauges are effective from 10  torr to 10  torr, and beyond. Thermal conductivity gauges rely on the fact that the ability of a gas to conduct heat decreases with pressure. In this type of gauge, a wire filament is heated by running current through it. A thermocouple or Resistance Temperature Detector (RTD) can then be used to measure

12496-459: The full armor/water-cooling, up to 8 megawatts of neutral beam injection will also be available for 10 seconds. An ion cyclotron resonance heating (ICRH) system will become available for physics operation in OP1.2. A system of sensors and probes based on a variety of complementary technologies will measure key properties of the plasma, including the profiles of the electron density and of

12638-426: The gas density decreases, the MFP increases, and when the MFP is longer than the chamber, pump, spacecraft, or other objects present, the continuum assumptions of fluid mechanics do not apply. This vacuum state is called high vacuum , and the study of fluid flows in this regime is called particle gas dynamics. The MFP of air at atmospheric pressure is very short, 70  nm , but at 100  mPa (≈ 10   Torr )

12780-416: The gases being measured. Ionization gauges are used in ultrahigh vacuum. They come in two types: hot cathode and cold cathode. In the hot cathode version an electrically heated filament produces an electron beam. The electrons travel through the gauge and ionize gas molecules around them. The resulting ions are collected at a negative electrode. The current depends on the number of ions, which depends on

12922-554: The heating systems were used that slowly increased the temperatures. Notable among these was the 1964 addition of a small particle accelerator to accelerate fuel ions to high enough energy to cross the magnetic fields, depositing energy within the reactor when they collided with other ions already inside. This method of heating, now known as neutral beam injection , has since become almost universal on magnetic confinement fusion machines. Model C spent most of its history involved in studies of ion transport. Through continual tuning of

13064-469: The impact of vacuum on human health, and on life forms in general. The word vacuum comes from Latin  'an empty space, void', noun use of neuter of vacuus , meaning "empty", related to vacare , meaning "to be empty". Vacuum is one of the few words in the English language that contains two consecutive instances of the vowel u . Historically, there has been much dispute over whether such

13206-836: The initial development phase was longer than expected, doubling the personnel costs. In July 2011, the President of the Max Planck Society , Peter Gruss , announced that the United States would contribute $ 7.5 million under the program "Innovative Approaches to Fusion" of the United States Department of Energy . 54°04′23″N 13°25′26″E  /  54.073°N 13.424°E  / 54.073; 13.424 Stellarator A stellarator confines plasma using external magnets. Scientists aim to use stellarators to generate fusion power . It

13348-507: The interstellar absorbing medium may be simply the ether, [it] is characteristic of a gas, and free gaseous molecules are certainly there". Thereafter, however, luminiferous aether was discarded. Later, in 1930, Paul Dirac proposed a model of the vacuum as an infinite sea of particles possessing negative energy, called the Dirac sea . This theory helped refine the predictions of his earlier formulated Dirac equation , and successfully predicted

13490-476: The ions and electrons. Spitzer introduced the concept of a divertor , a magnet placed around the tube that pulled off the very outer layer of the plasma. This would remove the ions before they drifted too far and hit the walls. It would also remove any heavier elements in the plasma. Vacuum The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example,

13632-437: The long axis of the tube. But, as Fermi pointed out, when the solenoid is bent into a ring, the electrical windings would be closer together on the inside than the outside. This would lead to an uneven field across the tube, and the fuel will slowly drift out of the center. Since the electrons and ions would drift in opposite directions, this would lead to a charge separation and electrostatic forces that would eventually overwhelm

13774-577: The machines for themselves. Their tests, made using a laser -based system developed for the ZETA reactor in England, verified the Soviet claims of electron temperatures of 1,000 eV. What followed was a "veritable stampede" of tokamak construction worldwide. At first the US labs ignored the tokamak; Spitzer himself dismissed it out of hand as experimental error. However, as new results came in, especially

13916-443: The magnetic force. Some additional force needs to counteract this drift, providing long-term confinement . Spitzer's key concept in the stellarator design is that the drift that Fermi noted could be canceled out through the physical arrangement of the vacuum tube. In a torus, particles on the inside edge of the tube, where the field was stronger, would drift up, while those on the outside would drift down (or vice versa). However, if

14058-431: The magnetic lines, they would do so in opposite directions, and at very high rotational speeds. This leads to the possibility of collisions between particles circling different lines of force as they circulate through the reactor, which due to purely geometric reasons, causes the fuel to slowly drift outward. This process eventually causes the fuel to either collide with the structure or cause a large charge separation between

14200-523: The magnetic system and the addition of the new heating methods, in 1969, Model C eventually reached electron temperatures of 400 eV. Through this period, a number of new potential stellarator designs emerged, which featured a simplified magnetic layout. The Model C used separate confinement and helical coils, as this was an evolutionary process from the original design which had only the confinement coils. Other researchers, notably in Germany, noted that

14342-420: The main plasma-facing components during this first campaign (instead of the divertor modules). Experimental observations confirmed 3D modeling predictions that showed heat and particle flux deposition patterns on the limiters in clear correlation with the lengths of the open magnetic field lines in the plasma boundary. Such tests were planned to continue for about a month, followed by a scheduled shut-down to open

14484-616: The name " Project Matterhorn " because he felt "the work at hand seemed difficult, like the ascent of a mountain." Two sections were initially set up, S Section working on the stellarator under Spitzer, and B Section working on bomb design under Wheeler. Matterhorn was set up at Princeton's new Forrestal Campus, a 825 acres (334 ha) plot of land the University purchased from the Rockefeller Institute for Medical Research when Rockefeller relocated to Manhattan . The land

14626-465: The net field, a second set of coils running poloidally around the outside of the helical magnet produces a second vertical field that mixes with the helical one. The result is a much simpler layout, as the poloidal magnets are generally much smaller and there is ample room between them to reach the interior, whereas in the original layout the toroidal confinement magnets are relatively large and leave little room between them. A further update emerged from

14768-418: The next few months, Spitzer produced a series of reports outlining the conceptual basis for the stellarator, as well as potential problems. The series is notable for its depth; it not only included a detailed analysis of the mathematics of the plasma and stability but also outlined a number of additional problems like heating the plasma and dealing with impurities. With this work in hand, Spitzer began to lobby

14910-578: The overall field layout by replacing the elements. These "modular coils" are now a major part of ongoing research. In 1968, scientists in the Soviet Union released the results of their tokamak machines, notably their newest example, T-3. The results were so startling that there was widespread scepticism. To address this, the Soviets invited a team of experts from the United Kingdom to test

15052-459: The partial vacuum lapsed until 1850 when August Toepler invented the Toepler pump and in 1855 when Heinrich Geissler invented the mercury displacement pump, achieving a partial vacuum of about 10 Pa (0.1  Torr ). A number of electrical properties become observable at this vacuum level, which renewed interest in further research. While outer space provides the most rarefied example of

15194-401: The particle were made to alternate between the inside and outside of the tube, the drifts would alternate between up and down and would cancel out. The cancellation is not perfect, leaving some net drift, but basic calculations suggested drift would be lowered enough to confine plasma long enough to heat it sufficiently. Spitzer's suggestion for doing this was simple. Instead of a normal torus,

15336-446: The particles to travel without rotation. B-65, completed in 1957, was built using the new "racetrack" layout. This was the result of the observation that adding helical coils to the curved portions of the device produced a field that introduced the rotation purely through the resulting magnetic fields. This had the added advantage that the magnetic field included shear , which was known to improve stability. B-3, also completed in 1957,

15478-406: The performance being seen in the Soviet machines, besting the Model C's results by over ten times. From that point, PPPL was the primary developer of the tokamak approach in the US, introducing a series of machines to test various designs and modifications. The Princeton Large Torus of 1975 quickly hit several performance numbers that were required for a commercial machine, and it was widely believed

15620-710: The physics of the machine. More than 300 discharges with helium were done in December and January with gradually increasing temperatures finally reaching six million degrees Celsius, to clean the vacuum vessel walls and test the plasma diagnostic systems. Then, on 3 February 2016, production of the first hydrogen plasma initiated the science program. The highest temperature plasmas were produced by four-megawatt microwave heater pulses lasting one second; plasma electron temperatures reached 100 MK, while ion temperatures reached 10 MK. More than 2,000 pulses were conducted before shutdown. Five poloidal graphite limiters served as

15762-403: The plasma circle the magnetic lines of force. One way to provide some confinement would be to place a tube of fuel inside the open core of a solenoid . A solenoid creates magnetic lines running down its center, and fuel would be held away from the walls by orbiting these lines of force. But such an arrangement does not confine the plasma along the length of the tube. The obvious solution is to bend

15904-497: The plasma ring inside the torus to expand until it hit the walls of the reactor. After World War II , a number of researchers began considering different ways to confine a plasma. George Paget Thomson of Imperial College London proposed a system now known as z-pinch , which runs a current through the plasma. Due to the Lorentz force , this current creates a magnetic field that pulls the plasma in on itself, keeping it away from

16046-619: The power of the magnetic fields, requiring superconducting magnets and huge confinement volumes. The cost of such a machine was such that the involved parties banded together to begin the ITER project. As the problems with the tokamak approach grew, interest in the stellarator approach reemerged. This coincided with the development of advanced computer aided planning tools that allowed the construction of complex magnets that were previously known but considered too difficult to design and build. New materials and construction methods have increased

16188-530: The powers of God, led to the conclusion that God could create a vacuum if he so wished. From the 14th century onward increasingly departed from the Aristotelian perspective, scholars widely acknowledged that a supernatural void exists beyond the confines of the cosmos itself by the 17th century. This idea, influenced by Stoic physics , helped to segregate natural and theological concerns. Almost two thousand years after Plato, René Descartes also proposed

16330-429: The pressure in a vacuum, depending on what range of vacuum is needed. Hydrostatic gauges (such as the mercury column manometer ) consist of a vertical column of liquid in a tube whose ends are exposed to different pressures. The column will rise or fall until its weight is in equilibrium with the pressure differential between the two ends of the tube. The simplest design is a closed-end U-shaped tube, one side of which

16472-631: The pressure in the gauge. Hot cathode gauges are accurate from 10  torr to 10 torr. The principle behind cold cathode version is the same, except that electrons are produced in a discharge created by a high voltage electrical discharge. Cold cathode gauges are accurate from 10  torr to 10  torr. Ionization gauge calibration is very sensitive to construction geometry, chemical composition of gases being measured, corrosion and surface deposits. Their calibration can be invalidated by activation at atmospheric pressure or low vacuum. The composition of gases at high vacuums will usually be unpredictable, so

16614-620: The quality and power of the magnetic fields, improving performance. New devices have been built to test these concepts. Major examples include Wendelstein 7-X in Germany, the Helically Symmetric Experiment (HSX) in the US, and the Large Helical Device in Japan. W7X and LHD use superconducting magnetic coils . The lack of an internal current eliminates some of the instabilities of the tokamak, meaning

16756-465: The reactor successfully produced helium plasma (with temperatures of about 1 MK) for about 0.1 s. For this initial test with about 1 mg of helium gas injected into the evacuated plasma vessel, microwave heating was applied for a short 1.3 MW pulse. The aim for the OP 1.1 was to conduct integrated testing of the most important systems as quickly as possible and to gain first experience with

16898-438: The reactor walls. The 50 non-planar coils are used for adjusting the magnetic field. It aims for a plasma density of 3 × 10 particles per cubic metre, and a plasma temperature of 60–130  megakelvins (MK). The W7-X is optimised along the quasi-isodynamic principle. The main components are the magnetic coils, cryostat , plasma vessel, divertor and heating systems. The coils ( NbTi in aluminium) are arranged around

17040-436: The reactor would be reversed after half an orbit and it would drift downward again. The cancellation was not perfect, but it appeared this would so greatly reduce the net drift rates that the fuel would remain trapped long enough to heat it to the required temperatures. His 1958 description was simple and direct: Magnetic confinement in the stellarator is based on a strong magnetic field produced by solenoidal coils encircling

17182-433: The realization that the total field could be produced through a series of independent magnets shaped like the local field. This results in a series of complex magnets that are arranged like the toroidal coils of the original layout. The advantage of this design is that the magnets are entirely independent; if one is damaged it can be individually replaced without affecting the rest of the system. Additionally, one can re-arrange

17324-423: The same overall magnetic field configuration could be achieved with a much simpler arrangement. This led to the torsatron or heliotron layout. In these designs, the primary field is produced by a single helical magnet, similar to one of the helical windings of the "classical" stellarator. In contrast to those systems, only a single magnet is needed, and it is much larger than those in the stellarators. To produce

17466-421: The second straight section, still on the outside edge of that tube. However, because the tubes are crossed, when it reaches the second half-torus it enters it on the inside edge. As it travels through this section it drifts back up. This effect would reduce one of the primary causes of drift in the machine, but there were others to consider as well. Although the ions and electrons in the plasma would both circle

17608-427: The sides. Unfortunately, this arrangement would not confine the plasma along the length of the tube, and the plasma would be free to flow out the ends. The obvious solution to this problem is to bend the tube around into a torus (a ring or donut) shape. Motion towards the sides remains constrained as before, and while the particles remain free to move along the lines, in this case, they will simply circulate around

17750-409: The simple torus. This led to the construction of the Model B, which had the problem that the magnets were not well mounted and tended to move around when they were powered to their maximum capacity of 50,000 gauss. A second design also failed for the same reason, but this machine demonstrated several-hundred-kilovolt X-rays that suggested good confinement. The lessons from these two designs led to

17892-563: The stellarator concept ended in the US replaced by tokamaks. Research continued in Germany and Japan, where several new designs were built. The tokamak ultimately proved to have problems similar to the stellarators, but for different reasons. Since the 1990s, the stellarator design has seen renewed interest. New methods of construction have increased the quality and power of the magnetic fields, improving performance. A number of new devices have been built to test these concepts. In 1934, Mark Oliphant , Paul Harteck and Ernest Rutherford were

18034-603: The stellarator should be more stable at similar operating conditions. On the downside, since it lacks the confinement provided by the current found in a tokamak, the stellarator requires more powerful magnets to reach any given confinement. The stellarator is an inherently steady-state machine, which has several advantages from an engineering standpoint. As part of a renewed push for fusion power from around 2018, private sector stellarator projects have emerged and in number compete with, though are much less developed than, tokamak projects, such as Renaissance Fusion and Proxima Fusion,

18176-583: The stellarator was matching the Bohm diffusion rate, which suggested it would never be a practical fusion device. The release of information on the USSR's tokamak design in 1968 indicated a leap in performance. After debate within the US industry, PPPL converted the Model C stellarator to the Symmetrical Tokamak (ST) as a way to confirm or deny these results. ST confirmed them, and large-scale work on

18318-552: The stellarator was originally expected to reach completion in 2006. Assembly began in April 2005. Problems with the coils took about 3 years to fix. The schedule slipped into late 2015. A three-laboratory American consortium (Princeton, Oak Ridge, and Los Alamos) became a partner in the project, paying €6.8 million of the eventual total cost of €1.06 billion. In 2012, Princeton University and the Max Planck Society announced

18460-439: The system, so that a high quality vacuum is one with very little matter left in it. Vacuum is primarily measured by its absolute pressure , but a complete characterization requires further parameters, such as temperature and chemical composition. One of the most important parameters is the mean free path (MFP) of residual gases, which indicates the average distance that molecules will travel between collisions with each other. As

18602-408: The system. Fluids cannot generally be pulled, so a vacuum cannot be created by suction . Suction can spread and dilute a vacuum by letting a higher pressure push fluids into it, but the vacuum has to be created first before suction can occur. The easiest way to create an artificial vacuum is to expand the volume of a container. For example, the diaphragm muscle expands the chest cavity, which causes

18744-455: The temperature of the filament. This temperature is dependent on the rate at which the filament loses heat to the surrounding gas, and therefore on the thermal conductivity. A common variant is the Pirani gauge which uses a single platinum filament as both the heated element and RTD. These gauges are accurate from 10 torr to 10  torr, but they are sensitive to the chemical composition of

18886-465: The theory of classical electromagnetism, free space has the following properties: The vacuum of classical electromagnetism can be viewed as an idealized electromagnetic medium with the constitutive relations in SI units: relating the electric displacement field D to the electric field E and the magnetic field or H -field H to the magnetic induction or B -field B . Here r

19028-411: The time Model C began operations, information collected from previous machines was making it clear that it would not be able to produce large-scale fusion. Ion transport across the magnetic field lines was much higher than classical theory suggested. Greatly increased magnetic fields of the later machines did little to address this, and confinement times simply were not improving. Attention began to turn to

19170-482: The tube around into a torus (donut) shape, so that any one line forms a circle, and the particles can circle forever. However, this solution does not actually work. For purely geometric reasons, the magnets ringing the torus are closer together on the inside curve, inside the "donut hole". Fermi noted this would cause the electrons to drift away from the nuclei, eventually causing them to separate and cause large voltages to develop. The resulting electric field would cause

19312-431: The vacuum in the steam space of the condenser, that is, the exhaust of the last stage of the turbine. Mechanical or elastic gauges depend on a Bourdon tube, diaphragm, or capsule, usually made of metal, which will change shape in response to the pressure of the region in question. A variation on this idea is the capacitance manometer , in which the diaphragm makes up a part of a capacitor. A change in pressure leads to

19454-417: The vacuum vessel and line it with protective carbon tiles and install a "divertor" for removing impurities and heat from the plasma. The science program continued while gradually increasing discharge power and duration. The special magnetic field topology was confirmed in 2016. Operational phase 1 (OP1.1) concluded 10 March 2016 and an upgrade phase began. Operational phase 1 continued (OP1.2) in 2017 to test

19596-582: The walls of the reactor. This eliminates the need for magnets on the outside, avoiding the problem Fermi noted. Various teams in the UK had built a number of small experimental devices using this technique by the late 1940s. Another person working on controlled fusion reactors was Ronald Richter , a German scientist who moved to Argentina after the war. His thermotron used a system of electrical arcs and mechanical compression (sound waves) for heating and confinement. He convinced Juan Perón to fund development of an experimental reactor on an isolated island near

19738-501: Was a greatly enlarged B-2 machine with ultra-high vacuum and pulsed confinement up to 50,000 gauss and projected confinement times as long as 0.01 second. The last of the B-series machines was the B-66, completed in 1958, which was essentially a combination of the racetrack layout from B-65 with the larger size and energy of the B-3. Unfortunately, all of these larger machines demonstrated

19880-533: Was developed based on the predecessor Wendelstein 7-AS experimental reactor. As of 2023, the Wendelstein 7-X reactor is the world's largest stellarator device. After two successful operation phases ending in October 2018, the reactor was taken offline for upgrades. The upgrade completed in 2022. New fusion experiments in February 2023 demonstrated longer confinement and increased power. The goal of this phase

20022-543: Was located about 3 miles (4.8 km) from the main Princeton campus and already had sixteen laboratory buildings. Spitzer set up the top-secret S Section in a former rabbit hutch. It was not long before the other labs began agitating for their own funding. Tuck had managed to arrange some funding for his Perhapsatron through some discretionary budgets at LANL, but other teams at LANL, Berkeley and Oak Ridge (ORNL) also presented their ideas. The AEC eventually organized

20164-575: Was sent to the Atoms for Peace show in Geneva . However, when the heating system was modified, the coupling increased dramatically, demonstrating temperatures within the heating section as high as 1,000 electronvolts (160 aJ). Two additional machines were built to study pulsed operation. B-64 was completed in 1955, essentially a larger version of the B-1 machine but powered by pulses of current that produced up to 15,000 gauss. This machine included

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