Fusion reactors, ignition temperature

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. 

Compared with fission reactors, operation of fusion reactors is more complicated because of the high ignition temperatures, the necessity to confine the plasma, and problems with the construction materials. On the other hand, the radioactive inventory of fusion reactors is appreciably smaller. Fission products are not formed and actinides are absent. The radioactivity in fission reactors is given by the tritium and the activation products produced in the construction materials. This simplifies the waste problems considerably. Development of thermonuclear reactors based on the D-D reaction would reduce the radioactive inventory even further, because T would not be needed. The fact that the energy produced by fusion of the D atoms contained in 1 litre of water corresponds to the energy obtained by burning 120 kg coal is very attractive. 

Of the several fusion reactions, deuterium-tritium fusion is the most feasible, as it has the lowest ignition temperature, 4E7 "K. (See Reaction 1.) Deuterium comprises 0.15 percent of naturally occurring hydrogen, whereas tritium is produced by neutron fission of iithium-6 that is irradiated in a blanket surrounding a nuclear reactor core. Nuclide separation is required to produce the deuterium and possibly the lithium. The... 

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