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Encyclopedia > Aneutronic fusion

Aneutronic fusion is any form of fusion power where no more than 1% of the total energy released is carried by neutrons. Since the most-studied fusion reactions release up to 80% of their energy in neutrons, successful aneutronic fusion would greatly reduce problems associated with neutron radiation such as ionizing damage, neutron activation, and requirements for biological shielding, remote handling, and safety issues. Some proponents also see a potential for dramatic cost reductions by converting the energy of the charged fusion products directly to electricity. The conditions required to harness aneutronic fusion are much more extreme than those required for the conventional deuteriumtritium (DT) fuel cycle, and even these conditions have not yet been produced experimentally. Even if aneutronic fusion is one day shown to be scientifically feasible, it is still speculative whether power production could be made economical. Internal view of the JET tokamak superimposed with an image of a plasma taken with a visible spectrum video camera. ... This article or section does not adequately cite its references or sources. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Neutron radiation consists of free neutrons. ... Radiation hazard symbol. ... Neutron activation is the process by which neutron radiation induces radioactivity in materials. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Tritium (symbol T or ³H) is a radioactive isotope of hydrogen. ...

Contents

Candidate aneutronic reactions

There are a few fusion reactions that have no neutrons as products on any of their branches. Those with the largest cross sections are these: In nuclear and particle physics, the concept of a cross section is used to express the likelihood of interaction between particles. ...

D + 3He   4He (3.6 MeV) +   p (14.7 MeV)
D + 6Li 4He + 22.4 MeV
p + 6Li   4He (1.7 MeV) +   3He (2.3 MeV)
3He + 6Li 4He   +   p + 16.9 MeV
3He + 3He   4He   + p  
p + 7Li 4He + 17.2 MeV
p + 11B 4He + 8.7 MeV

The first two of these use deuterium as a fuel, and D–D side reactions will produce some neutrons. Although these can be minimized by running hot and deuterium-lean, the fraction of energy released as neutrons will probably be several percent, so that these fuel cycles, although neutron-poor, do not classify as aneutronic according to the 1% threshold. Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Helium-3 is a non-radioactive and light isotope of helium. ... Helium-4 is a non-radioactive and light isotope of helium. ... The electronvolt (symbol eV) is a unit of energy. ... This article is about the chemical element named Lithium. ... For other uses, see Proton (disambiguation). ... For other uses, see Proton (disambiguation). ... For other uses, see Boron (disambiguation). ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ...


The rates of the next two reactions (involving p, 3He, and 6Li) are not particularly high in a thermal plasma. When they are treated as a chain, however, they offer the possibility of an enhanced reactivity due to a non-thermal distribution. The product 3He from the first reaction could participate in the second reaction before thermalizing, and the product p from the second reaction could participate in the first reaction before thermalizing. Unfortunately, detailed analyses have not shown sufficient reactivity enhancement to overcome the inherently low cross section. In physics, a particles distribution function is a function of seven variables, , which gives the number of particles per unit volume in phase space. ...


The pure 3He reaction suffers from a fuel-availability problem. 3He occurs naturally on the Earth in only minuscule amounts, so it would either have to be bred from reactions involving neutrons (counteracting the potential advantage of aneutronic fusion), or mined from extraterrestrial bodies. The top several meters of the surface of the Moon is relatively rich in 3He, on the order of 0.01 parts per million by weight[1], but mining this resource and returning it to Earth would be very difficult and expensive. 3He could in principle be recovered from the atmospheres of the gas giant planets, but this would be even more challenging. Helium-3 is a non-radioactive and light isotope of helium. ... This article does not cite any references or sources. ...


The p–7Li reaction has no advantage over p–11B. On the contrary, its cross section is somewhat lower.


For the above reasons, most studies of aneutronic fusion concentrate on the last reaction, p–11B.


Technical challenges

Temperature

Despite the suggested advantages of aneutronic fusion, the vast majority of fusion research effort has gone toward D–T fusion because the technical challenges of hydrogen-boron (p–11B) fusion are considered so formidable. To begin with, hydrogen-boron fusion requires ion energies or temperatures almost ten times higher than those for D–T fusion. For any given densities of the reacting nuclei, the reaction rate for hydrogen boron achieves its peak rate at around 600 keV (6.6 billion degrees Celsius or 6.6 gigakelvins) while D–T has a peak at around 66 keV (730 million degrees Celsius).[2] Kev can refer to either: A regional term for the chav social group in the United Kingdom An abbreviation - keV - of the unit Kiloelectronvolt An abbreviation for the given name Kevin. ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ...


Power balance

In addition, the peak reaction rate of p–11B is only one third that for D–T, so that better confinement of the plasma energy is required. The confinement is usually characterized by the time τ the energy must be retained so that the fusion power exceeds the power required to heat the plasma. Various requirements can be derived, the most commonly used being the product with the density, nτ, and the product with the pressure nTτ, both of which are called the Lawson criterion. The nτ required for p–11B is 45 times higher than that for DT. The nTτ required is 500 times higher.[3] (See here for more details). Since the confinement properties of conventional approaches to fusion such as the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts. This article or section does not cite its references or sources. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...


In most fusion plasmas, bremsstrahlung radiation is a major channel of energy loss. (See here for more details.) For the p–11B reaction, some calculations indicate that the bremsstrahlung power will be at least 1.74 times larger than the fusion power. The corresponding ratio for the 3He-3He reaction is only slightly more favorable at 1.39. This is not applicable to non-neutral plasmas, and different in anisotropic plasmas. (help· info), (from the German bremsen, to brake and Strahlung, radiation, thus, braking radiation), is electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when deflected by another charged particle, such as an atomic nucleus. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ...


In conventional fusion reactor designs, whether based on magnetic confinement or inertial confinement concepts, the bremsstrahlung can easily escape the plasma and is considered a pure energy loss term. The outlook would be more favorable if the radiation could be reabsorbed by the plasma. Absorption occurs primarily via Thomson scattering on the electrons,[4] which has a total cross section of σT = 6.65×10−29 m². In a 50–50 D–T mixture this corresponds to a range of 6.3 g/cm².[5] This is considerably higher than the Lawson criterion of ρR > 1 g/cm², which is already difficult to attain, but might not be out of the range of future inertial confinement systems.[6] Magnetic confinement fusion is an approach to fusion energy that uses magnetic fields to confine the fusion fuel in the form of a plasma. ... Inertial confinement fusion using lasers rapidly progressed in the late 1970s and early 1980s from being able to deliver only a few joules of laser energy (per pulse) to a fusion target to being able to deliver tens of kilojoules to a target. ... In physics, Thomson scattering is the scattering of electromagnetic radiation by a charged particle. ... This article or section does not cite its references or sources. ...


In very high magnetic fields, on the order of a megatesla, a quantum mechanical effect is theorised to suppress the transfer of energy from the ions to the electrons.[7] According to one calculation,[8] the bremsstrahlung losses could be reduced to half the fusion power or less. In a strong magnetic field the cyclotron radiation is even larger than the bremsstrahlung. In a megatesla field, an electron would lose its energy to cyclotron radiation in a few picoseconds if the radiation could escape. However, in a sufficiently dense plasma (ne > 2.5×1030 m−3),[9] the cyclotron frequency is less than twice the plasma frequency. In this well-known case, the cyclotron radiation is trapped inside the plasmoid and cannot escape, except from a very thin surface layer. SI unit. ... For a less technical and generally accessible introduction to the topic, see Introduction to quantum mechanics. ... Cyclotron radiation is a type of bremsstrahlung (braking) radiation. ... The gyroradius (also known as radius of gyration, Larmor radius or cyclotron radius) defines the radius of the circular motion of a charged particle in the presence of a uniform magnetic field. ... In physics, plasma oscillations, often referred to as Langmuir waves or plasma waves, are periodic oscillations of charge density in conducting media such as plasmas or metals. ...


While megatesla fields have not yet been obtained in the laboratory, fields of 0.3 megatesla have been produced with high intensity lasers,[10] and fields of 0.02-0.04 megatesla have been observed with the dense plasma focus device.[11][12] A Dense Plasma Focus (DPF) is a plasma machine that produces, by electromagnetic acceleration and compression, short-lived plasma that is so hot and dense that it becomes a copious multi-radiation source. ...


At much higher densities still (ne > 6.7×1034 m−3), the electrons will be Fermi degenerate, which will suppress the bremsstrahlung losses, both directly and by reducing the energy transfer from the ions to the electrons.[13] If the necessary conditions could be attained, this would open up the possibility of net energy production from p–11B or D–3He fuel. The feasibility of a reactor based solely on this effect remains low, however, because the gain is predicted to be less than 20, while more than 200 is usually considered to be necessary. (There are, however, effects that might improve the gain substantially). Degenerate matter is matter which has sufficiently high density that the dominant contribution to its pressure arises from the Pauli exclusion principle. ...


Power density

In every published fusion power plant design, the part of the plant that produces the fusion reactions is much more expensive than the part that converts the nuclear power to electricity. In that case, as indeed in most power systems, the power density is a very important characteristic.[14] If the power density can be doubled without changing the design too much, then the cost of electricity will be at least halved. In addition, the confinement time required depends on the power density.


It is, however, not trivial to compare the power density produced by two different fusion fuel cycles. The case most favorable to p–11B relative to D–T fuel is a (hypothetical) confinement device that only works well at ion temperatures above about 400 keV, where the reaction rate parameter <σv> is equal for the two fuels, and that runs with low electron temperature. In terms of confinement time required, p–11B would even have an advantage, because the energy of the charged products of that reaction is two and a half times higher than that for D–T. As soon as these assumptions are relaxed, for example by considering hot electrons, by allowing the D–T reaction to run at a lower temperature, or by including the energy of the neutrons in the calculation, the power density advantage shifts back to D–T.


The most common assumption is to compare the power densities at the same pressure, with the ion temperature for each reaction chosen to maximize the power density, and with the electron temperature equal to the ion temperature. Although confinement schemes can be and sometimes are limited by other factors, most well-investigated schemes have, not surprisingly, some kind of pressure limit. Under these assumptions, the power density for p–11B is about 2100 times smaller than that for D–T. If the device runs with cold electrons, the ratio is still about 700. These numbers are another indication that aneutronic fusion power will not be possible with any mainline confinement concept.


Current research

There are a number of efforts aimed at achieving hydrogen-boron fusion, using different fusion devices. One approach, using the dense plasma focus[15], has been funded by NASA’s Jet Propulsion Laboratory, the Air Force Research Laboratory and the Chilean Nuclear Energy Commission, among others.[16] In 2001, Lawrenceville Plasma Physics (LPP) Inc. reported achieving ion energies of over 100 keV using a plasma focus device at Texas A&M University.[17] A test of this approach, also known as “Focus fusion” is now underway, in a joint project with LPP, at the Thermonuclear Plasma Laboratory in Santiago Chile.[18] Researchers from University of Illinois and from the Air Force Research Laboratory have described how a dense plasma focus device using hydrogen-boron fuel can be used for space propulsion.[19] A Dense Plasma Focus (DPF) is a plasma machine that produces, by electromagnetic acceleration and compression, short-lived plasma that is so hot and dense that it becomes a copious multi-radiation source. ... For the singer/songwriter, see Jon Peter Lewis. ... The United States Air Force Research Laboratory with headquarters at Wright-Patterson Air Force Base, Ohio, was created in October 1997. ... Texas A&M University redirects here. ... Focus Fusion takes place in a Dense Plasma Focus produced by a Plasma Focus Device (PFD). ... A Corner of Main Quad The University of Illinois at Urbana-Champaign (UIUC, U of I, or simply Illinois), is the oldest, largest, and most prestigious campus in the University of Illinois system. ...


In yet another approach, pioneered by Robert W. Bussard and funded by the US Navy, an inertial electrostatic confinement device called a Polywell is used.[20][21] Robert W. Bussard (born 1928) is an American physicist working primarily in nuclear fusion energy research. ... Inertial electrostatic confinement (often abbreviated as IEC) is a concept for retaining a plasma using an electrostatic field. ... WB-6, the latest experiment, assembled The Polywell is a gridless inertial electrostatic confinement fusion concept utilizing multiple magnetic mirrors. ...


None of the efforts noted here has yet actually tested its device with hydrogen-boron fuel, so the anticipated performance is based on extrapolating from theory, experimental results with other fuels and from simulations.


While the z-pinch device has not been mentioned as a possible hydrogen-boron reactor, ion energies of interest to such reactions, up to 300 keV, were reported by researchers for the Z-machine at Sandia National Laboratory.[22] In 2005, a Russian team produced hydrogen-boron aneutronic fusions using a picosecond laser.[23] However, the number of the resulting α particles (around 103 per laser pulse) was extremely low. Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero   Planetfall Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar... Sandia National Laboratories is a major United States Department of Energy research and development national laboratory with two locations, one in Albuquerque, New Mexico and the other in Livermore, California. ...


Residual radiation from a p–11B reactor

Detailed calculations show that at least 0.1% of the reactions in a thermal p–11B plasma would produce neutrons, and the energy of these neutrons would account for less than 0.2% of the total energy released.[24]


These neutrons come primarily from the reaction[25]

11B + α14N + n + 157 keV

The reaction itself produces only 157 keV, but the neutron will carry a large fraction of the alpha energy, which will be close to Efusion/3 = 2.9 MeV. Another significant source of neutrons is the reaction An alpha particle is deflected by a magnetic field Alpha radiation consists of helium-4 nuclei and is readily stopped by a sheet of paper. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ...

11B + p → 11C + n - 2.8 MeV

These neutrons will be less energetic, with an energy comparable to the fuel temperature. In addition, 11C itself is radioactive, but will decay to negligible levels within several hours as its half life is only 20 minutes.


Since these reactions involve the reactants and products of the primary fusion reaction, it would be difficult to further lower the neutron production by a significant fraction. A clever magnetic confinement scheme could in principle suppress the first reaction by extracting the alphas as soon as they are created, but then their energy would not be available to keep the plasma hot. The second reaction could in principle be suppressed relative to the desired fusion by removing the high energy tail of the ion distribution, but this would probably be prohibited by the power required to prevent the distribution from thermalizing.


In addition to neutrons, large quantities of hard X-rays will be produced by bremsstrahlung, and 4, 12, and 16 MeV gamma rays will be produced by the fusion reaction In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... (help· info), (from the German bremsen, to brake and Strahlung, radiation, thus, braking radiation), is electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when deflected by another charged particle, such as an atomic nucleus. ... This article is about electromagnetic radiation. ...

11B + p → 12C + γ + 16.0 MeV

with a branching probability relative to the primary fusion reaction of about 10−4.[26] Carbon 12 is a stable isotope of the element carbon. ... This article is about electromagnetic radiation. ...


Finally, isotopically pure fuel will have to be used and the influx of impurities into the plasma will have to be controlled to prevent neutron-producing side reactions like these: For other uses, see Isotope (disambiguation). ...

11B + d → 12C + n + 13.7 MeV
d + d → 3He + n + 3.27 MeV

Fortunately, with careful design, it should be possible to reduce the occupational dose of both neutron and gamma radiation to operators to a negligible level. The primary components of the shielding would be water to moderate the fast neutrons, boron to absorb the moderated neutrons, and metal to absorb X-rays. The total thickness needed should be about a meter, most of that being water.[27]


Direct conversion of energy

Aneutronic fusion reactions produce the overwhelming bulk of their energy in the form of charged particles instead of neutrons. This means that energy could be converted directly into electricity by various techniques. Many proposed direct conversion techniques are based on mature technology derived from other fields, such as microwave technology, and some involve equipment that is more compact and potentially cheaper than that involved in conventional thermal production of electricity.


In contrast, fusion fuels like deuterium-tritium (DT), which produce most of their energy in the form of neutrons, require a standard thermal cycle, in which the neutrons are used to boil water, and the resulting steam drives a large turbine and generator. This equipment is sufficiently expensive that about 80% of the capital cost of a typical fossil-fuel electric power generating station is in the thermal conversion equipment.[citation needed]


Thus, fusion with DT fuels could not significantly reduce the capital costs of electric power generation even if the fusion reactor that produces the neutrons were cost-free. (Fuel costs would, however be greatly reduced.) But according to proponents, aneutronic fusion with direct electric conversion could, in theory, produce electricity with reduced capital costs.


Direct conversion techniques can either be inductive, based on changes in magnetic fields, or electrostatic, based on making charged particles work against an electric field.[28] If the fusion reactor worked in a pulsed mode, inductive techniques could be used.


A sizable fraction of the energy released by aneutronic fusion would not remain in the charged fusion products but would instead be radiated as x-rays.[29] Some of this energy could also be converted directly to electricity. X-rays passing though an array of conducting foils would transfer some of their energy to electrons, which can then be captured electrostatically.[citation needed] Since X-rays can go through far greater thickness of material than electrons can, many hundreds or even thousands of layers would be needed to absorb most of the X-rays.


References

  1. ^ The estimation of helium-3 probable reserves in lunar regolith
  2. ^ For confinement concepts that are pressure limited, the optimum operating temperatures are about 5 times lower, but the ratio is still roughly ten-to-one.
  3. ^ Both of these figures assume the electrons have the same temperature as the ions. If operation with cold electrons is possible, as discussed below, the relative disadvantage of p–11B would be a factor of three smaller, as calculated here.
  4. ^ Lecture 3 : Accelerated charges and bremsstrahlung, lecture notes in astrophysics from Chris Flynn, Tuorla Observatory
  5. ^ miT = 2.5×(1.67×10−24 g)/(6.65×10−25 cm²) = 6.28 g/cm²
  6. ^ Robert W. B. Best. "Advanced Fusion Fuel Cycles". Fusion Technology, Vol. 17 (July 1990), pp. 661–5.
  7. ^ G.S. Miller, E.E. Salpeter, and I. Wasserman, Deceleration of infalling plasma in the atmospheres of accreting neutron stars. I. Isothermal atmospheres, Astrophysical Journal, 314: 215-233, 1987 March 1. In one case, they report an increase in the stopping length by a factor of 12.
  8. ^ E.J. Lerner, Prospects for p11B fusion with the Dense Plasma Focus: New Results (Proceedings of the Fifth Symposium on Current Trends in International Fusion Research), 2002, http://www.arxiv.org/ftp/physics/papers/0401/0401126.pdf
  9. ^ Assuming 1 MT field strength. This is several times higher than solid density.
  10. ^ http://jasmine.kues.kyoto-u.ac.jp/pps/PPSProceedings/05_Beiersdorfer_LaserPPS.pdf
  11. ^ Bostick, W.H. et al, Ann. NY Acad. Sci., 251, 2 (1975)
  12. ^ The magnetic pressure at 1 MT would be 4×1011 MPa. For comparison, the tensile strength of stainless steel is typically 600 MPa.
  13. ^ S.Son, N.J.Fisch, Aneutronic fusion in a degenerate plasma, Physics Letters A 329 (2004) 76–82 or online
  14. ^ Comparing two different types of power systems involves many factors in addition to the power density. Two of the most important are the volume in which energy is produced in comparison to the total volume of the device, and the cost and complexity of the device. In contrast, the comparison of two different fuel cycles in the same type of machine is generally much more robust.
  15. ^ http://video.google.com/videoplay?docid=-1518007279479871760&q=Google+tech+talks+lerner&pr=goog-sl
  16. ^ JPL Contract 959962, JPL Contract 959962
  17. ^ E.J. Lerner, Prospects for p11B fusion with the Dense Plasma Focus: New Results (Proceedings of the Fifth Symposium on Current Trends in International Fusion Research), 2002, http://www.arxiv.org/ftp/physics/papers/0401/0401126.pdf
  18. ^ http://focusfusion.org/log/index.php/site/article/lpp_cchen_collaboration_announcement/
  19. ^ Thomas, Robert; Yang, Yang; Miley, G. H.; Mead, F. B Advancements in Dense Plasma Focus (DPF) for Space Propulsion SPACE TECHNOLOGY AND APPLICATIONS INT.FORUM-STAIF 2005:. AIP Conference Proceedings, Volume 746, pp. 536–543 (2005)
  20. ^ Bussard, R. W. & Jameson L. W., Inertial-Electrostatic-Fusion Propulsion Spectrum: Air-Breathing to Interstellar Flight, Journal of Propulsion and Power Vol. 11, No. 2, March–April 1995
  21. ^ Should Google go Nuclear? - A video of Dr. Bussard presenting his concept to an audience at Google
  22. ^ Malcolm Haines et al, Viscous Heating of Ions through Saturated Fine-Scale MHD Instabilities in a Z-Pinch at 200-300 keV Temperature; Phys. Rev. Lett. 96, 075003 (2006)
  23. ^ V.S. Belyaev et al, Observation of neutronless fusion reactions in picosecond laser plasmas, Physical Review E 72 (2005), or online, mentioned in [email protected] on August 26, 2005 : Lasers trigger cleaner fusion
  24. ^ Heindler and Kernbichler, Proc. 5th Intl. Conf. on Emerging Nuclear Energy Systems, 1989, pp. 177-82. Even though 0.1% is a small fraction, the dose is rate still high enough to require very good shielding, as illustrated by the following calculation. Assume we have a very small reactor producing 30 kW of total fusion power (a full-scale power reactor might produce 100,000 times more than this) and 30 W in the form of neutrons. If there is no significant shielding, a worker in the next room, 10 m away, might intercept (0.5 m²)/(4 pi (10 m)2) = 4×10−4 of this power, i.e., 0.012 W. With 70 kg body mass and the definition 1 gray = 1 J/kg, we find a dose rate of 0.00017 Gy/s. Using a quality factor of 20 for fast neutrons, this is equivalent to 3.4 millisieverts. The maximum yearly occupational dose of 50 mSv will be reached in 15 s, the fatal (LD50) dose of 5 Sv will be reached in half an hour. If very effective precautions are not taken, the neutrons would also activate the structure so that remote maintenance and radioactive waste disposal would be necessary.
  25. ^ W. Kernbichler, R. Feldbacher, M. Heindler. "Parametric Analysis of p–11B as Advanced Reactor Fuel" in Plasma Physics and Controlled Nuclear Fusion Research (Proc. 10th Int. Conf., London, 1984) IAEA-CN-44/I-I-6. Vol. 3 (IAEA, Vienna, 1987).
  26. ^ As with the neutron dose, shielding is essential with this level of gamma radiation. The neutron calculation in the previous note would apply if the production rate is decreased a factor of ten and the quality factor is reduced from 20 to 1. Without shielding, the occupational dose from a small (30 kW) reactor would still be reached in about an hour.
  27. ^ El Guebaly, Laial, A., Shielding design options and impact on reactor size and cost for the advanced fuel reactor Aploo, Proceedings- Symposium on Fusion Engineering, v.1, 1989, pp.388–391. This design refers to D–He3, which actually produces more neutrons than p–11B fuel.
  28. ^ Miley, G.H., et al, Conceptual design for a B-3He IEC Pilot plant, Proceedings--Symposium on Fusion Engineering, v. 1, 1993, pp. 161-164; L.J. Perkins et al, Novel Fusion energy Conversion Methods, Nuclear Instruments and Methods in Physics Research, A271, 1988, pp. 188–96
  29. ^ Quimby, D.C., High Thermal Efficiency X-ray energy conversion scheme for advanced fusion reactors, ASTM Special technical Publication, v.2, 1977, pp. 1161–1165

This article or section does not cite its references or sources. ... For other uses, see Pascal. ... Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ... The 630 foot (192 m) high, stainless-clad (type 304) Gateway Arch defines St. ... The gray (symbol: Gy) is the SI unit of absorbed dose. ... The sievert (symbol: Sv) is the SI derived unit of dose equivalent. ... An LD50 test being administered In toxicology, the LD50 or colloquially semilethal dose of a particular substance is a measure of how much constitutes a lethal dose. ...

External links


Fusion power
v  d  e

Atomic nucleus | Nuclear fusion | Nuclear power | Nuclear reactor | Timeline of nuclear fusion | Plasma physics | Magnetohydrodynamics | Neutron flux | Fusion energy gain factor | Lawson criterion Internal view of the JET tokamak superimposed with an image of a plasma taken with a visible spectrum video camera. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... This article is about applications of nuclear fission reactors as power sources. ... Core of a small nuclear reactor used for research. ... Timeline of significant events in the study and use of nuclear fusion: 1929 - Atkinson and Houtermans used the measured masses of light elements and applied Einsteins discovery that E=mc² to predict that large amounts of energy could be released by fusing small nuclei together. ... A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ... Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics) is the academic discipline which studies the dynamics of electrically conducting fluids. ... neutron flux n : the rate of flow of neutrons; the number of neutrons passing through a unit area in unit time via dictionary. ... The fusion energy gain factor, usually expressed with the symbol Q, is the ratio of fusion power produced in a nuclear fusion reactor to the power required to maintain the plasma in steady state. ... This article or section does not cite its references or sources. ...

Methods of fusing nuclei

Magnetic confinement: – Tokamak – Spheromak – Stellarator – Reversed field pinch – Field-Reversed Configuration – Levitated Dipole
Inertial confinement: –
Laser driven – Z-pinch – Bubble fusion (acoustic confinement) – Fusor (electrostatic confinement)
Other forms of fusion: –
Muon-catalyzed fusion – Pyroelectric fusion – Migma – Polywell – Dense plasma focus The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Magnetic Fusion Energy (MFE) is a sustained nuclear fusion reaction in a plasma that is contained by magnetic fields. ... This article is about the fusion reactor device. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Stellarator magnetic field and magnets A stellarator is a device used to confine a hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction. ... Reversed-Field Pinch is a toroidal magnetic confinement scheme. ... A Field-Reversed Configuration (FRC) is a device developed for magnetic fusion energy research that confines a plasma on closed magnetic field lines without a central penetration. ... A Levitated Dipole is a unique form of fusion reactor technology using a solid superconducting torus, magnetically levitated in the reactor chamber. ... Inertial confinement fusion using lasers rapidly progressed in the late 1970s and early 1980s from being able to deliver only a few joules of laser energy (per pulse) to a fusion target to being able to deliver tens of kilojoules to a target. ... In inertial confinement fusion (ICF), nuclear fusion reactions are initiated by heating and compressing a target – a pellet that most often contains deuterium and tritium – by the use of intense laser or ion beams. ... It has been suggested that this article or section be merged into Pinch (plasma physics). ... Bubble fusion or sonofusion is the common name for a nuclear fusion reaction hypothesized to occur during sonoluminescence, an extreme form of acoustic cavitation; officially, this reaction is termed acoustic inertial confinement fusion (AICF) since the inertia of the collapsing bubble wall confines the energy causing a rise in temperature. ... U.S. Patent 3,386,883 - fusor — June 4, 1968 The Farnsworth–Hirsch Fusor, or simply fusor, is an apparatus designed by Philo T. Farnsworth to create nuclear fusion. ... Inertial electrostatic confinement (often abbreviated as IEC) is a concept for retaining a plasma using an electrostatic field. ... Muon-catalyzed fusion is a process allowing nuclear fusion to take place at room temperature. ... Pyroelectric fusion is a technique for achieving nuclear fusion by using an electric field generated by pyroelectric crystals to accelerate ions of deuterium (tritium might also be used someday) into a metal hydride target also containing detuerium (or tritium) with sufficient kinetic energy to cause these ions to fuse together. ... Migma was a proposed inertial electrostatic confinement fusion reactor designed by Bogdan Maglich around 1973. ... WB-6, the latest experiment, assembled The Polywell is a gridless inertial electrostatic confinement fusion concept utilizing multiple magnetic mirrors. ... A Dense Plasma Focus (DPF) is a plasma machine that produces, by electromagnetic acceleration and compression, short-lived plasma that is so hot and dense that it becomes a copious multi-radiation source. ...

List of fusion experiments

Magnetic confinement devices
ITER (International) |
JET (European) | JT-60 (Japan) | Large Helical Device (Japan) | KSTAR (Korea) | EAST (China) | T-15 (Russia) | DIII-D (USA) | Tore Supra (France) | TFTR (USA) | NSTX (USA) | NCSX (USA) | UCLA ET (USA) | Alcator C-Mod (USA) | LDX (USA) | H-1NF (Australia) | MAST (UK) | START (UK) | ASDEX Upgrade (Germany) | Wendelstein 7-X (Germany) | TCV (Switzerland) | DEMO (Commercial) Experiments directed toward developing fusion power are invariably done with dedicated machines which can be classified according to the principles they use to confine the plasma fuel and keep it hot. ... ITER is an international tokamak (magnetic confinement fusion) research/engineering project designed to prove the scientific and technological feasibility of a full-scale fusion power reactor. ... Split image of JET with right side showing hot plasma during a shot. ... JT-60 (JT stands for Japan Torus) is the flagship of Japans magnetic fusion program, previously run by the Japan Atomic Energy Research Institute (JAERI) and currently run by the Japan Atomic Energy Agencys (JAEA) Naka Fusion Institute[1] in Ibaraki Prefecture, Japan. ... Categories: Stub | Nuclear technology ... The KSTAR, or Korean Superconducting Tokamak Advanced Reactor is a magnetic fusion device being built at the Korea Basic Science Institute in Daejon, South Korea. ... The Experimental Advanced Superconducting Tokamak (EAST, internally called HT-7U) is a project being undertaken to construct an experimental superconducting tokamak magnetic fusion energy reactor in Hefei, the capital city of Anhui Province, in eastern China. ... The T-15 is a Russian nuclear fusion research reactor, based on the (Russian-invented) tokamak design. ... DIII-D or D3-D is the name of a tokamak machine developed in the 1980s by General Atomics in San Diego, USA, as part of the ongoing effort to achieve magnetically confined fusion. ... Tore Supra is a tokamak français en activité après larrêt du TFR (Tokamak de Fontenay-aux-Roses) et de Petula (à Grenoble). ... The Tokamak Fusion Test Reactor (TFTR) was an experimental fusion test reactor built at Princeton Plasma Physics Laboratory (in Princeton, New Jersey) circa 1980. ... The National Spherical Torus Experiment (NSTX) is an innovative magnetic fusion device that was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle. ... The National Compact Stellarator Experiment (NCSX) is a plasma confinement experiment being conducted at the Princeton Plasma Physics Laboratory. ... The UCLA Electric Tokamak is a low field (0. ... Alcator C-Mod is a tokamak, a magnetically confined nuclear fusion device, at the MIT Plasma Science and Fusion Center. ... The Levitated Dipole Experiment (LDX) is a project devoted to researching a type of nuclear fusion which utilizes a floating superconducting torus to provide an axisymmetric magnetic field which is used to contain plasma. ... The H-1 flexible Heliac is a three field-period helical axis stellarator located in the Research School of Physical Sciences and Engineering at the Australian National University. ... The Mega Ampere Spherical Tokamak, or MAST experiment is a nuclear fusion experiment in operation at Culham since December 1999. ... The Small Tight Aspect Ratio Tokamak, or START was a nuclear fusion experiment that used magnetic confinement to hold plasma. ... The ASDEX Upgrade divertor tokamak (Axially Symmetric Divertor EXperiment) went into operation at the Max-Planck-Institut für Plasmaphysik, Garching in 1991. ... Wendelstein 7-X is an experimental stellarator (nuclear fusion reactor) currently being built in Greifswald, Germany by the Max-Planck-Institut für Plasmaphysik (IPP), which will be completed by 2012. ... Tokamak à Configuration Variable (TCV): inner view, with the graphite-claded torus. ... This article or section contains speculation and may try to argue its points. ...


Inertial confinement devices
Laser driven:NIF (USA) |
OMEGA laser (USA) | Nova laser (USA) | Novette laser (USA) | Nike laser (USA) | Shiva laser (USA) | Argus laser (USA) | Cyclops laser (USA) | Janus laser (USA) | Long path laser (USA) | 4 pi laser (USA) | LMJ (France) | Luli2000 (France) | GEKKO XII (Japan) | ISKRA lasers (Russia) | Vulcan laser (UK) | Asterix IV laser (Czech Republic) | HiPER laser (European)
Non-laser driven:Z machine (USA) |
PACER (USA)
A construction worker inside NIFs 10 meter target chamber. ... The Laboratory for Laser Energetics (LLE) is a scientific research facility which is part of the University of Rochesters south campus, located in Rochester, New York. ... View down Novas laser bay between two banks of beamlines. ... The Novette target chamber with two laser chains visible in background. ... Final amplifier of the Nike laser where laser beam energy is increased from 150 J to ~5 Kj by passing through a krypton/fluorine/argon gas mixture excited by irradiation with two opposing 670,000 volt electron beams. ... The Shiva laser was an extremely powerful 20 beam infrared neodymium glass (silica glass) laser built at Lawrence Livermore National Laboratory in 1977 for the study of inertial confinement fusion and long-scale-length laser-plasma interactions. ... Argus laser overhead view. ... The single beam Cyclops laser at LLNL around the time of its completion in 1975. ... The Janus laser as it appeared in 1975. ... The Long Path laser was an early high energy infrared laser at the Lawrence Livermore National Laboratory used to study inertial confinement fusion. ... Physicist Frank Rainer (inset), who was involved in laser research and development at LLNL since 1966, holds the target chamber seen at the center of the larger picture. ... Laser Mégajoule (LMJ) is an experimental inertial confinement fusion (ICF) device being built in France by the French nuclear science directorate, CEA. Laser Mégajoule plans to deliver about 1. ... LULI2000 is a high-power laser system dedicated to scientific research. ... GEKKO XII is a high-power 12-beam neodymium doped glass laser at the Osaka Universitys Institute for Laser Engineering completed in 1983, which is used for high energy density physics and inertial confinement fusion research. ... The ISKRA-4 and ISKRA-5 lasers are lasers which were built by the Russian federation at RFNC-VNIIEF in Arzamas-16() with the ~2Kj output ISKRA-4 laser being completed in 1979 and the ~30Kj output ISKRA-5 laser which was completed in 1989. ... The Vulcan laser is an 8 beam 2. ... The Asterix IV laser in Prague (commonly reffered to by the acronym PALS for Prague Asterix Laser System) is a high power photolytically pumped iodine gas laser which is capable of producing ~300 to 500 picosecond long pulses of light at the fundamental line of 1. ... HiPER is an experimental laser-driven inertial confinement fusion (ICF) device currently undergoing preliminary design for possible construction in the European Union starting around 2010. ... Zork universe Zork games Zork Anthology Zork trilogy Zork I   Zork II   Zork III Beyond Zork   Zork Zero   Planetfall Enchanter trilogy Enchanter   Sorcerer   Spellbreaker Other games Wishbringer   Return to Zork Zork: Nemesis   Zork Grand Inquisitor Zork: The Undiscovered Underground Topics in Zork Encyclopedia Frobozzica Characters   Kings   Creatures Timeline   Magic   Calendar... The PACER project, carried out at Los Alamos National Laboratory in the mid-1970s, explored the possibility of a fusion power system that would involve exploding small hydrogen bombs (fusion bombs)—or, as stated in a later proposal, fission bombs—inside an underground cavity. ...


See also: International Fusion Materials Irradiation Facility The International Fusion Material Irradiation Facility, also known as IFMIF, is an international scientific research program designed to test materials for suitability for use in a fusion reactor. ...


  Results from FactBites:
 
Fusion rocket (431 words)
The advantage over a fission rocket is that less radiation is produced (depending on the fusion reaction), which requires less shielding, and that there is greater energy density in the fuel.
Of the speculative spacecraft propulsion systems that have been proposed, fusion is likely to be feasible in the medium term as steady progress is being made towards self-sustaining fusion reactions.
A small pellet of fusion fuel (with a diameter of a couple of millimeters) would be ignited by an electron beam[?], a laser or even a tiny amount of antimatter.
Fusion rocket - Wikipedia, the free encyclopedia (789 words)
For space flight, the main advantage of fusion would be the very high specific impulse, the main disadvantage the (probable) large mass of the reactor.
A small pellet of fusion fuel (with a diameter of a couple of millimeters) would be ignited by an electron beam or a laser.
In principle, the Helium-3-Deuterium reaction or an aneutronic fusion reaction could be used to maximize the energy in charged particles and to minimize radiation, but it is highly questionable whether it is technically feasible to use these reactions.
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