Fusion, nuclear controlled

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. 

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... 

Plasma can be generated in many ways viz, by detonation (see Detonation Plasma in Vol 4, D258-L to D264-L, D348 D471-R to D474-R) by controlled nuclear fusion, the abundant energy source of the future (Refs 3,... 

A more constructive approach to nuclear fusion—one that achieves a controlled release of nuclear energy—is to heat a plasma, or ionized gas, by passing an electric current through it. The very fast ions in the plasma are kept away from the walls of the container with magnetic fields. This method of achieving fusion is the subject of intense research and is beginning to show signs of success (Fig. 17.27). 

FIGURE 17.27 Research into controlled nuclear fusion is being carried out in several countries. Here we see the Tokomak fusion test reactor at the Princeton Plasma Physics Laboratory. 

Nuclear fusion reactors do not split uranium atoms. They fuse hydrogen atoms in a process similar to that which occurs in the Sun and other stars. Although fusion physics is a common occurrence in stars, controlled fusion experiments continue. In 1994, theTokamak facility at Princeton reached a fusion plasma temperature of 510 million degrees and had a power output of 10.7 megawatts. 

Other uses of lasers include eye surgery on detached retinas, spot welding, holography, isotope separation, accurate determination of the moon s orbit by reflection of laser light off a reflector placed on the moon s surface, and laser-guided bombs and missiles. Possible future uses include terrestrial and extraterrestrial communication, applications to computers, and production of the high temperatures needed for controlled nuclear-fusion reactions. 

Sia.fl IAEA Plasma Physits it Controlled Nuclear Fusion Research 1994. Vol. 4. Bernan Associates, Lunham. MD. 1993. 

The main appeal of nuclear fusion as a power source is that the hydrogen isotopes used as fuel are cheap and plentiful and that the fusion products are nonra-dioactive and nonpolluting. The technical problems that must be solved before achieving a practical and controllable fusion method are staggering, however. Not the least of the problems is that a temperature of approximately 40 million kelvins is needed to initiate the fusion process. 

L. D. Stodiek, W. R. Stooksberry, R. Strachan, J.D. Suckewer, S. Takahasi, H. Tait, G.D., Ulrickson, M. von Goeler, S. Yamada, M. "PLT Neutral Beam Heating Results" in Proc. of the 7th Intern. Conf. on Plasma Physics and Controlled Nuclear Fusion Research, Innsbruck, Austria, 1979, (IAEA, Vienna, 1979) Vol. 1, p. 167. 

On Earth, scientists are studying plasmas as a source for nuclear fusion reactions. In theory, if we can understand howto make atoms combine nuclei in controlled conditions, we can produce large amounts of energy that could be used to make electricity. 

Rovner, L. H., Chen, K. Y., Chin, J. Proc. ANL Topical Meeting on the Technology of Controlled Nuclear Fusion. Santa Fe 1978... 

Scientists hope to someday use controlled nuclear fusion to produce energy. Nuclear fusion, which involves the coming together of light nuclei to form heavier ones, is the process by which stars generate energy. In order... 

Atoms are first stripped of their electrons at very high temperatures this creates a plasma (ionized gas) of positive ions. Then the positive ions must be brought into close enough proximity, so that the strong attractive force between nucleons can overwhelm the Coulomb repulsion between them. Magnetic fields can confine hot plasmas of ions, provided that collective instabilities of these plasmas can be controlled. For a successful nuclear fusion reactor, three requirements must be met (1) The density of the plasma must exceed some critical value p. (2) The plasma confinement time must exceed some critical value t. (3) The temperature of the plasma must exceed some critical value 9... 

Soltwisch H., Stodiek W., Manickam J., Schlueter J., Proc. 11th Int. Conf. Plasma Physics Controlled Nuclear Fusion Research, Kyoto, Vol. 1, 263 (1986)... 

For a controlled nuclear fusion reaction the following parameters are important ... 

The problems to be solved in controlling the nuclear fusion reaction have, however, been enormous. The most obvious challenge is simply to find a way to hold the nuclear fusion reaction in place as it occurs. One cannot build a machine made out of metal, plastic, glass, or any other common kind of material. At the temperatures at which fusion occurs, any one of these materials would vaporize instantly. So how does one contain the nuclear fusion reaction ... 

A second method for creating controlled nuclear fusion makes use of a laser beam or a beam of electrons or atoms. In this approach, hydrogen isotopes are suspended at the middle of the machine in tiny hollow glass spheres known as microballoons. The microballoons are then bombarded by the laser, electron, or atomic beam... 

Nuclear power is any method of doing work that makes use of nuclear fission or nuclear fusion reactions. hi its broadest sense, the term refers to both the uncontrolled release of nuclear energy, as in fission or fusion weapons, and to the controlled release of energy, as in nuclear power plants. Most commonly, however, the expression nuclear power is reserved for the latter. Approximately 430 nuclear reactors devoted to the manufacture of electricity are operating worldwide. 

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