Magnetic fusion reactor

Sheffield, J. (1994). The Physics of Magnetic Fusion Reactors. Reviews of Modern Physics 66 1015-1103. 

For 1978 the course was titled Driven magnetic fusion reactors - giving a cloak of responsibility to the consideration of mirrors. For a rousing start we had Dr R F Post on The Philosophy of Fusion Research. Many of the points he raised are quite pertinent to our discussion of unconventionals and alternatives. ... 

R.F. Post, "Driven Magnetic Fusion Reactors", B. Brunelli,... 

C. Baker et al., Trends and Developments in Magnetic Fusion Reactor Concepts, Nuc. Tech./Fusion, V 1, Jan. 

Schematic of a fusion reactor, assuming a generally toroidal shape of the plasma and magnetic fusion. The principles emphasized are central hot core (red) at 100 million degrees, blanket and heat exchanger, shield, energy conversion, and the handling of D, T, and the "ash" He.

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... 

One possible way to achieve nuclear fusion is to use magnetic fields to confine the reactant nuclei and prevent them from touching the walls of the container, where they would quickly slow down below the velocity required for fusion. Using 400-ton magnets, it is possible to sustain the reaction for a fraction of a second. To achieve a net evolution of energy, this time must be extended to about one second. A practical fusion reactor would have to produce 20 times as much energy as it consumes. Optimists predict that this goal may be reached in 50 years. 

Among several conceptual designs of fusion reactors, the machines based on magnetic confinement, such as Tokamak- and mirror-type reactors, employ a... 

Neutronic calculations show that fast neutron fluxes at fusion reactor magnet locations are rather high and the energy deposited by neutrons compares to or exceeds that by y-rays [2]. It is therefore important to establish the characteristics of radiation damage due to fast neutrons in comparison with those due to y-rays. 

These results indicate that the newly developed 3DFRP are potentially component materials of fusion reactors. In fact, the research groups of Japan [78] and the US [79] are planning to examine the cryogenic properties of irradiated 3DFRP for insulating materials of fusion magnets. 

The electrical properties of insulators for superconducting magnets are of crucial importance in relation to the operational reliability of fusion reactors [81], In the present section, the characteristics in original electrical properties of polymers at cryogenic temperatures are briefly introduced and then the effects of radiation on these properties are surveyed. 

The research and development efforts on polymer materials for fusion reactors have been intensified in recent years. Some polymers and composites are able to withstand the radiation doses in excess of 108 Gy even at cryogenic temperatures. Furthermore, international research projects on organic insulators used for fusion magnets are currently in progress. As one of the important subjects, the combined effects of intense radiation and thermal cycling are being tested. 

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... 

In the Tokamak fusion reactor depicted in Fig. 21.9, electric current to the poloidal coils on the primary magnetic transformer generates the axial current in the secondary plasma composed of deuterium and tritium ions. These ions are heated to ignition temperature and then the reaction becomes self-sustaining. The toroidal field coil suspends the plasma away from the metal conducting walls. Contact with the wall would both cool the plasma below ignition temperature and contaminate the plasma with heavy ions. The relevant reactions are given below. 

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