Fusion reactions

Ninety-three grams of ammonium hydrogen fluoride and 40 g. of boric acid are mixed in an iron dishf and heated. The two substances react readily with the liberation of steam and ammonia and the formation of a homogeneous melt. After cooling, the crystalline mass is broken, dissolved in about 100 ml. of hot water, and allowed to crystallize. The crystals are filtered and dried. Additional crystals of somewhat lower purity may be obtained by evaporation of the filtrate. The yield depends only upon the number of crops of crystals obtained and may be nearly quantitative. 

Ammonium tetrafluoborate is a clear crystalline solid that sublimes when heated strongly. It is soluble in 100 ml. of water to the extent of 25 g. at 16 and 97 g. at 100° 

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Calculate the energy release in kilocalories per mole (kcal/mol) of He for the cold fusion reaction... 

Fusion of a nucleus of with one of helium gives 0 Eventually the helium too becomes de pleted and gravitational attraction causes the core to contract and its temperature to increase to the point at which various fusion reactions give yet heav ler nuclei... 

The NH4PO2F2 can be extracted from the soHd reaction product with boiling methanol (80). Alkali metal difluorophosphates are prepared from the hexafluorophosphates by one of the following fusion reactions (81) ... 

The reactions of deuterium, tritium, and helium-3 [14762-55-17, He, having nuclear charge of 1, 1, and 2, respectively, are the easiest to initiate. These have the highest fusion reaction probabiUties and the lowest reactant energies. 

Once a fusion reaction has begun in a confined plasma, it is planned to sustain it by using the hot, charged-particle reaction products, eg, alpha particles in the case of D—T fusion, to heat other, colder fuel particles to the reaction temperature. If no additional external heat input is required to sustain the reaction, the plasma is said to have reached the ignition condition. Achieving ignition is another primary goal of fusion research. 

In the spring of 1989, it was announced that electrochemists at the University of Utah had produced a sustained nuclear fusion reaction at room temperature, using simple equipment available in any high school laboratory. The process, referred to as cold fusion, consists of loading deuterium into pieces of palladium metal by electrolysis of heavy water, E)20, thereby developing a sufficiently large density of deuterium nuclei in the metal lattice to cause fusion between these nuclei to occur. These results have proven extremely difficult to confirm (20,21). Neutrons usually have not been detected in cold fusion experiments, so that the D-D fusion reaction familiar to nuclear physicists does not seem to be the explanation for the experimental results, which typically involve the release of heat and sometimes gamma rays. 

Room temperature fusion reactions, albeit low probabiHty ones, are not a new concept, having been postulated in 1948 and verified experimentally in 1956 (22), in a form of fusion known as muon-catalized fusion. Since the 1989 announcement, however, international scientific skepticism has grown to the point that cold fusion is not considered a serious subject by most scientists. FoUow-on experiments, conducted in many prestigious laboratories, have failed to confirm the claims, and although some unexplained and intellectually interesting phenomena have been recorded, the results have remained irreproducable and, thus far, not accepted by the scientific community. 

Helium, plentiful in the cosmos, is a product of the nuclear fusion reactions that are the prime source of stellar energy. The other members of the hehum-group gases are thought to have been created like other heavier elements by further nuclear condensation reactions occurring at the extreme temperatures and densities found deep within stars and in supernovas. 

Laser-Assisted Thermonuclear Fusion. An application with great potential importance, but which will not reach complete fmition for many years, is laser-assisted thermonuclear fusion (117) (see Fusion energy). The concept iavolves focusiag a high power laser beam onto a mixture of deuterium [7782-39-0] and tritium [10028-17-8] gases. The mixture is heated to a temperature around 10 K (10 keV) (see Deuterium AMD tritium). At this temperature the thermonuclear fusion reaction... 

Tritium is produced in heavy-water-moderated reactors and sometimes must be separated isotopicaHy from hydrogen and deuterium for disposal. Ultimately, the tritium could be used as fuel in thermonuclear reactors (see Fusionenergy). Nuclear fusion reactions that involve tritium occur at the lowest known temperatures for such reactions. One possible reaction using deuterium produces neutrons that can be used to react with a lithium blanket to breed more tritium. 

High temperature is an important requirement for the attainment of fusion reactions in a plasma. The conditions necessary for extracting as much energy from the plasma as went into it is the Lawson criterion, which states that the product of the ion density and the confinement or reaction time must exceed 10 s/cm in the most favorable cases (173). If the coUisions are sufficiently violent, the Lawson criterion specifies how many of them must occur to break even. Conventional magnetic confinement involves fields of as much as 10 T (10 G) with large (1 m ) plasmas of low densities (<10 particles/cm ) and volumes and reaction times of about 1 s. If the magnetic flux can be compressed to values above 100 T (10 G), then a few cm ... 

Fluorosilicate Fusion. The fusion reaction of milled zircon with potassium hydrogen fluoride was used to prepare potassium hexafluorozirconate [16923-95-8] for studies leading to the first separation of hafnium and zirconium (30). Similar reactions using potassium hexafluorosihcate have been used (31,32) commercially in the United States and the former USSR ... 

It has been claimed that the D-D fusion reaction occurs when D2O is electroly2ed with a metal cathode, preferably palladium, at ambient temperatures. This claim for a cold nuclear fusion reaction that evolves heat has created great interest, and has engendered a voluminous titerature filled with claims for and against. The proponents of cold fusion report the formation of tritium and neutrons by electrolysis of D2O, the expected stigmata of a nuclear reaction. Some workers have even claimed to observe cold fusion by electrolysis of ordinary water (see, for example. Ref. 91). The claim has also been made for the formation of tritium by electrolysis of water (92). On the other hand, there are many experimental results that cast serious doubts on the reahty of cold fusion (93—96). Theoretical calculations indicate that cold fusions of D may indeed occur, but at the vanishingly small rate of 10 events per second (97). As of this writing the cold fusion controversy has not been entirely resolved. 

Nuclear Fusion Reactions. Tritium reacts with deuterium or protons (at sufftciendy high temperatures) to undergo nuclear fusion ... 

The confinement region in which nuclear fusion proceeds is surrounded by a blanket in which the neutrons produced by the fusion reaction are captured to produce tritium. Because of its favorable cross section for neutron capture, lithium is the favored blanket material. Various lithium blanket... 

Inorganic product of a fusion reaction. Material forms on cooling to a rigid state without undergoing crystallization. Glass is typically hard and brittle and will fracture conchoidally. 

Element 111 was synthesized and characterized by the same group during the period 8-17 December 1994 using the analogous cold-fusion reaction, ° Bi( Ni,n) lll, followed by observation of up to five successive cc-emissions which could be assigned to the chain ... 

Lasers are focused on a small pellet of fuel. This is an attempt to create a nuclear fusion reaction for the purpose of producing energy. (Corbis-Bettmann)... 

It IS often stated that unclear fusion tvill produce no radioactive hazard, but this is not correct. The most likely fuels for a fusion reactor would be deuterium and radioactive tritium, which arc isotopes of hydrogen. Tritium is a gas, and in the event of a leak it could easily be released into the surrounding environment. The fusion of deuterium and tritium produces neutrons, which would also make the reactor building itself somewhat radioactive. However, the radioactivity produced in a fusion reactor would be much shorter-lived than that from a fission reactor. Although the thermonuclear weapons (that use nuclear fusion), first developed in the 1950s provided the impetus for tremendous worldwide research into nuclear fusion, the science and technology required to control a fusion reaction and develop a commercial fusion reactor are probably still decades away. 

Particle beam lusion accelerator II (PEFA-II) was designed io deliver ai least IQO trillion waits ol power and was ihe first machine Mth ihe potential to Ingnite a controlled laboratory fusion reaction. (U.S. Department of Energy)... 

The most plausible fusion reaction for producing energy commercially involves two isotopes of hydrogen, deuterium (D) and tritium (T), or H and H. Deuterium contains one proton and one neutron for an atomic number of two. Tritium contains one proton and two neutrons for an atomic number of three. The reaction is... 

Other fusion reactions such as D plus "He" and D plus D (not to mention the II plus II of stars) require far more difficult physical conditions than D plus T, but offer potential advantages in reduced neutron production, and even larger reseiwes of potential energy in the case of D-D. 

Inertial confinement fusion has long succeeded in the context of militai y explosions—the hydrogen bomb. In the militai y application a fission bomb produces x-rays that drive an implosion of D-T fuel to enormous temperatures and densities such that fusion reactions occur during the short time that inertia keeps the fusing nuclei densely packed and hot. 

Also in 1950 Sakliarov and Tamm proposed an idea for a controlled thermonuclear fusion reactor, the TOKAMAK (acronym for the Russian phrase for toroidal chamber with magnetic coiF ), which achieved the highest ratio of output power to input power of any fusion device of the twentieth centuiy. This reactor grew out of interest in a controlled nuclear fusion reaction, since 1950. Sakharov first considered electrostatic confinement, but soon came to the idea of magnetic confinement. Tamm joined the effort with his work on particle motion in a magnetic field, including cyclotron motion, drifts, and magnetic surfaces. Sakharov and Tamm realized that... 

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