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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. The beams explosively detonate the outer layers of the target, accelerating the remaining target layers inward and sending a shock wave into the center. If the shock wave is powerful enough and if high enough density at the center is achieved some of the fuel will be heated enough to cause fusion reactions, releasing energy. In a target which has been heated and compressed to the point of thermonuclear ignition, energy can then heat surrounding fuel to cause it to fuse as well, creating a chain reaction that burns the fuel load, potentially releasing tremendous amounts of energy. Theoretically, if the reaction completes with perfect efficiency (a practically impossible feat), a small amount of fuel about the size of a pinhead releases the energy equivalent to a barrel of oil. The deuterium-tritium fusion reaction is considered the most promising for producing fusion power. ...
Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance of one atom in 6500 of hydrogen. ...
Tritium (symbol T or 3H) is a radioactive isotope of hydrogen. ...
Laser (US Air Force) A LASER (Light Amplification by Stimulated Emission of Radiation) is an optical device which uses a quantum mechanical effect called stimulated emission (discovered by Einstein while researching the photoelectric effect) in order to generate a coherent beam of light from a lasing medium of controlled purity...
A chain reaction is a sequence of reactions where a reactive product or biproduct causes more additional reactions. ...
Basic fusion
Fusion reactions combine lightweight atoms, such as hydrogen, together to form larger ones. Generally the reactions take place at such high temperatures that the atoms have been ionized, their electrons stripped off by the heat; thus, fusion is typically described in terms of "nuclei" instead of "atoms". General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...
An ion is an atom or group of atoms with a net electric charge. ...
Properties The electron is a subatomic particle. ...
Fusion reactions on a scale useful for energy production require a very large amount of energy to initiate in order to overcome the so-called Coulomb barrier or fusion barrier energy. Since the positively-charged nuclei are naturally repelling each other, this repulsive force must be overcome by providing some form of external energy. When this occurs, however, the reaction is a rather energetic one. Generally less energy will be needed to cause lighter nuclei to fuse, and when they do, more energy will be released. As the mass of the nuclei increase, there is a point where the reaction no longer gives off net energy -- the energy needed to overcome the energy barrier is greater than the energy released in the resulting fusion reaction. This point occurs when iron nuclei are formed and is the cause of death in some massive stars. This phenomenon plays no role in laboratory induced fusion however, since the energy and temperature required to form iron nuclei are very large. Fusion of heavy nuclei is possible using particle accelerators and is the method used to form very heavy transuranic elements such as Roentgenium for instance, though the method of achieving this fusion of heavy elements is far removed from the methods used in large scale fusion reactions which are desired in tokamak or ICF fusion reactors. The Coulomb barrier, named after physicist Charles-Augustin de Coulomb (1736—1806), is the energy barrier due to electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo nuclear fusion. ...
General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...
A particle accelerator uses electric fields to propel charged particles to great energies. ...
In chemistry, transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, the atomic number of Uranium. ...
General Name, Symbol, Number roentgenium, Rg, 111 Chemical series transition metals Group, Period, Block 11, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (272) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s1 (guess based on gold) Electrons per shell 2, 8, 18, 32, 32, 18...
The key to practical fusion power is to select a fuel that requires the minimum amount of energy to start, that is, the lowest barrier energy. The best fuel from this standpoint is a one to one mix of deuterium and tritium; both are heavy isotopes of hydrogen. The D-T mix has a low barrier because of its high ratio of neutrons to protons. The presence of neutral neutrons in the nuclei helps pull them together via the strong force; while the presence of positively charged protons pushes the nuclei apart via Coloumbic forces (the electromagnetic force). Tritium has one of the highest ratios of neutrons to protons of any element -- two neutrons and one proton. Adding protons or removing neutrons increases the energy barrier. Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance of one atom in 6500 of hydrogen. ...
Tritium (symbol T or 3H) is a radioactive isotope of hydrogen. ...
Isotopes are forms of a chemical element whose nuclei have the same atomic number, Z, but different atomic masses, A. The word isotope, meaning at the same place, comes from the fact that all isotopes of an element are located at the same place on the periodic table. ...
Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ...
The strong nuclear force or strong interaction (also called color force or colour force) is a fundamental force of nature which affects only quarks and antiquarks, and is mediated by gluons in a similar fashion to how the electromagnetic force is mediated by photons. ...
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ...
In order to create the required conditions, the fuel must be heated to tens of millions of degrees, and/or compressed to immense pressures. The temperature and pressure required for any particular fuel to fuse is known as the Lawson criterion. These conditions have been known since the 1950s when the first H-bombs were built. In nuclear fusion research, the Lawson Criterion is an important general measure of a system that defines the conditions needed for a fusion reactor to generate net output energy -- that is, produce more energy in the fusion reactions than is lost in thermal and other radiation out of the fuel. ...
The mushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 18 km (60,000 feet) above the epicenter. ...
ICF design The use of a nuclear bomb to ignite a fusion reaction makes the concept less than useful as a power source. Not only would the bombs be prohibitively expensive to produce, but there is a minimum size that a bomb can be built, defined roughly by the critical mass of the plutonium fuel used. Generally it seems difficult to build nuclear devices smaller than about 1 kiloton in size, which would make it a difficult engineering problem to extract power from the resulting explosions. Also the smaller a thermonuclear bomb is, the "dirtier" it is, that is to say, the percentage of energy produced in the explosion by fusion is decreased while the percent produced by fission reactions tends toward unity (100%). This did not stop efforts to design such a system however, leading to the PACER concept. A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ...
General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ...
Pacer could refer to: A type of British train, see Pacer (train). ...
If some source of compression could be found, other than a nuclear bomb, then the size of the reaction could be scaled down. This idea has been of intense interest to both the bomb-making and fusion energy communities. It was not until the 1970s that a potential solution appeared in the form of very large, very high power, high energy lasers, which were then being built for weapons and other research. The D-T mix in such a system is known as a target, containing much less fuel than in a bomb design (often only micro or milligrams), and leading to a much smaller explosive force.
Generally ICF systems use a single laser, the driver, whose beam is split up into a number of beams which are subsequently individually amplified by a trillion times or more. These are sent into the reaction chamber (called a target chamber) by a number of mirrors, positioned in order to illuminate the target evenly over its whole surface. The heat applied by the driver causes the outer layer of the target to explode, just as the outer layers of an H-bomb's fuel cylinder does when illuminated by the X-rays of the nuclear device. This causes extremely rapid heating and inward compression of the fuel inside the capsule and the formation of a shock wave, spherical instead of cylindrical, which further heats the fuel in the very center. In an ignition scale fuel capsule (used in a laser system which delivers enough energy capable to ignite it) the heat released by the reaction initiates fusion in the fuel surrounding it through heating by irradiation by the high energy alpha particles produced by the first fusion reactions at the center of the target, thereby leading to a chain reaction known as ignition. An alpha particle is deflected by a magnetic field Alpha particles or alpha rays are a form of particle radiation which are highly ionizing and have low penetration. ...
Issues with the successful achievement of ICF The primary problems with increasing ICF performance since the early experiments in the 1970s have been of energy delivery to the target and of symmetry of the imploding fuel and formation of a 'tight' shockwave convergence at fuel center. In order to focus the shock wave on the center of the target, the target must be made with extremely high precision and sphericity with abberations of no more than a few micrometres over its surface (inner and outer). Likewise the aiming of the laser beams must be extremely precise and the beams must arrive at the same time at all points on the target. Beam timing is a relatively simple issue and is solved by using delay lines in the beams' optical path to achieve picosecond levels of timing accuracy. Other problems plaguing the achievement of high symmetry and high temperatures/densities of the imploding target are so called "beam-beam" imbalance and beam anisotropy. These problems are, respectively, where the energy delivered by one beam may be higher or lower than other beams impinging on the target and of "hot spots" within a beam diameter hitting a target which induces uneven compression on the target surface, thereby forming rayleigh-taylor instabilities in the fuel, mixing it and reducing heating efficacy. All of these problems have been substantially mitigated in the past two decades of research by using various beam smoothing techniques and beam energy diagnostics to balance beam to beam energy. Target design has also improved tremendously over the years. Modern cryogenic targets tend to freeze a thin layer of the D-T mix just on the inside of a plastic sphere while irradiating it with a low power IR laser to smooth it's inner surface and monitoring it with a microscope equipped camera, thereby allowing the layer to be closely monitored ensuring its "smoothness". The term delay line has multiple meanings: In electronics and derivative fields such as telecommunications, a delay line is rigorously defined as a single-input-channel device, in which the output channel state at a given instant, t, is the same as the input channel state at the instant t...
IR or ir may stand for: Indian Railways Information Retrieval Informational Revolution Infrared Instrument Rating international relations Iran (ISO country code) Iridium (Ir), chemical symbol for the chemical element Iran Air (IATA alpha code designator) investor relations Ingenieur (Ir) Irish Rail Ingersoll-Rand Company Limited (NYSE trading symbol) Independent-Republican...
 A gold plated NIF hohlraum. Certain targets are surrounded by a small metal cylinder which is then irradiated by the laser beams instead of the target itself (called indirect drive ICF) (lasers are focused on the inner side of the cylinder almost instantly heating it to a superhot plasma which radiates mostly in X-rays) the X-rays from this plasma are then absorbed by the target surface, imploding it in the same way as if it had been hit with the lasers directly. The absorption of x-rays by the target is more efficient than the direct absorption of laser light, however these hohlraums or "burning chambers" also take up considerable energy to heat on their own, and are a debated feature even today; the equally numerous direct-drive designs do not use them. Often indirect drive hohlraum targets are used to simulate thermonuclear weapons tests due to the fact that the fusion fuel in them is also imploded mainly by X-ray radiation. Download high resolution version (1400x1750, 309 KB)A hohlraum mock up to be used on the NIF laser File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Download high resolution version (1400x1750, 309 KB)A hohlraum mock up to be used on the NIF laser File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
A construction worker inside NIFs 10 meter target chamber. ...
A variety of ICF drivers are being explored. Lasers have improved dramatically since the 1970s, scaling up in power from a few joules and kilo to gigawatts to megajoules (see NIF laser) and hundreds of terawatts, using mostly frequency doubled or tripled light from neodymium glass amplifiers. Other designs use heavy ion beams, or even imploding vaporized metal wires as in the z-pinch design. Ion beams are particularly interesting for commercial generation, as they are easy to create, control, and focus. On the downside, it is very difficult to achieve the very high energies required to implode a target efficiently and most ion-beam systems require the use of a hohlraum surrounding the target, reducing the overall efficiengy of the coupling of the ion beam's energy to that of the imploding target further. The joule (symbol J, also called newton meter, watt second, or coulomb volt) is the SI unit of energy and work. ...
A construction worker inside NIFs 10 meter target chamber. ...
The Z machine at Sandia National Laboratories in Albuquerque, New Mexico. ...
Brief history ICF experiments started in earnest in the mid-1970s, when lasers of the required power were first designed. This was long after the successful design of magnetic confinement fusion systems, and even the particularly successful tokamak design that was introduced in the early 1970s. Nevertheless, high funding during the energy crisis made for rapid gains in performance, and inertial designs were soon reaching the same sort of "below breakeven" conditions of the best magnetic systems. The magnetic fusion energy (MFE) program seeks to establish the conditions to sustain a nuclear fusion reaction in a plasma that is contained by magnetic fields. ...
A split image of the largest tokamak in the world, the JET, showing hot plasma in the right image during a shot. ...
An energy crisis is any great shortfall (or price rise) in the supply of energy to an economy. ...
One of the earliest serious attempts at an ICF design was Shiva, a 20-armed neodymium laser system built at the Lawrence Livermore National Laboratory (LLNL) that started operation in 1978. Shiva was a "proof of concept" design, followed by the NOVA design with 10 times the power. Funding for fusion research was severely constrained in the 80's, but NOVA nevertheless successfully gathered enough information for a next generation machine whose goal was ignition. Although net energy can be released even without ignition (the breakeven point), ignition is considered necessary for a practical power system. General Name, Symbol, Number neodymium, Nd, 60 Chemical series lanthanides Group, Period, Block ?, 6, f Appearance silvery white, yellowish tinge Atomic mass 144. ...
Aerial view of the lab and surrounding area. ...
The breakeven point in economics is the point at which cost or expenses and income are equal _ there is no net loss or gain, one has broken even. The point at which a firm or other economic entity breaks even is equal to its fixed costs divided by its...
 Picture showing history of the development of Nd:glass slabs for various LLNL laser amplifiers. The resulting design, now known as the National Ignition Facility, started construction at LLNL in 1997. Originally intended to start construction in the early 1990s, the NIF is now six years behind schedule and massively overbudget to the tune of over $1.4 billion. If this is to be typical of the development of such systems, it is unlikely they will ever be a practical power source. Nevertheless many of the problems appear to be due to the "big lab" mentality and shifting the focus from pure ICF research to the nuclear stewardship program, LLNLs traditional bombmaking role. NIF is now scheduled to "burn" in 2005, when the remaining lasers in the 192-beam array are finally installed. History of neodymium laser glass development at LLNL Template:PD US-Gov File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
History of neodymium laser glass development at LLNL Template:PD US-Gov File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Aerial view of the lab and surrounding area. ...
A construction worker inside NIFs 10 meter target chamber. ...
Inertial Fusion Energy Practical power plants built using ICF are now a serious area of study, known as inertial fusion energy, or IFE. IFE plants would deliver a continuous stream of targets to the reaction chamber, several a second typically, and capture the resulting heat to drive a conventional steam turbine. A steam turbine extracts the energy of pressurized superheated steam as mechanical movement. ...
ICF systems face some of the same problems as magnetic systems in generating useful power from their reactions. One of the primary concerns is how to successfully remove heat from the reaction chamber without interfering with the targets and driver beams. Another serious concern is that the huge number of neutrons released in the fusion reactions react with the plant, causing them to become radioactive themselves, as well as mechanically weakening metals. Fusion plants built of metal would have a fairly short lifetime and the core containment vessels will have to be replaced frequently. Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ...
One current concept in dealing with both of these problems, as shown in the HYLIFE-II baseline design, is to use a "waterfall" of flibe, a molten mix of fluorine, lithium and beryllium salts, which both protect the chamber from neutrons, as well as carrying away heat. The flibe is then passed into a heat exchanger where it heats water for use in the turbines. Another, Sombrero, uses a reaction chamber built of carbon fibre which has a very low neutron cross section. Cooling is provided by a molten ceramic, chosen because of its ability to stop the neutrons from travelling any further, while at the same time being an efficient heat transfer agent. General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ...
General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/gray Atomic mass 6. ...
General Name, Symbol, Number beryllium, Be, 4 Chemical series alkaline earth metals Group, Period, Block 2, 2, s Appearance white-gray metallic Atomic mass 9. ...
A heat exchanger is a device for transferring heat from one fluid to another, where the fluids are separated by a solid wall so that they never mix. ...
Carbon fiber composite is a strong, light and very expensive material. ...
In physics, and in particular in scattering theory, a differential cross section is defined by the probability to observe a scattered particle in a given quantum state per solid angle unit (i. ...
As a power source, even the best IFE reactors would be hard-pressed to deliver the same economics as coal. Coal can simply be dug up and burned for little cost, one of the main costs being shipping. An IFE plant would likely be similar in cost to a coal-fired one in terms of construction and machinery, but the fuel is considerably more complex while also being much more powerful. It is generally estimated that an IFE plant would have long-term operational costs about the same as coal, discounting development. HYLIFE-II claims to be about 40% less expensive than a coal plant of the same size, but considering the problems with NIF, it is simply too early to tell if this is realistic or not. Coal is a fossil fuel extracted from the ground either by underground mining, open-pit mining or strip mining. ...
See also A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ...
The magnetic fusion energy (MFE) program seeks to establish the conditions to sustain a nuclear fusion reaction in a plasma that is contained by magnetic fields. ...
The deuterium-tritium fusion reaction is considered the most promising for producing fusion power. ...
Sketch of induced nuclear fission, a neutron (n) strikes a uranium nucleus which splits into similar products (F. P.), and releases more neutrons to continue the process, and energy in the form of gamma and other radiation. ...
Muon-catalyzed fusion is a process allowing nuclear fusion to take place at room temperature. ...
Antimatter catalysed nuclear pulse propulsion is a variation of nuclear pulse propulsion based upon the injection of antimatter into a mass of nuclear fuel which normally would not be useful in propulsion. ...
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. ...
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. ...
External link - Inertial Fusion Energy: A Tutorial on the Technology and Economics
- National Ignition Facility Project
- Igniting a Fsion Face Off
- Zpinch Home Page
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