ceeds about 300,000 meters per second. At maximum compression of the fuel, which is now in a cool plasma state, the energy in converging shock waves is sufficient to heat the vary center of the fuel to temperatures high enough to induce fusion reactions. If the product of mass and size of this highly compressed fuel material is large enough, energy will be generated through fusion reactions before the plasma disassembles. Under proper conditions, more energy can be released than is required to compresses, and shock-heat the fuel to thermonuclear burning conditions. The physical processes in ICF bear relationship to those in thermonuclear weapons and in star formation—namely, gravitational collapse, compression heating, and the onset of nuclear fusion. The situation in star formation differs in one respect: after gravitational collapse ceases and star begins to expand again due to heat from exoergic nuclear fusion reactions, the expansion is arrested by the gravity force associated with the enormous mass of the star. In a star a state of equilibrium in both size and temperature is achieved. In ICF, by contrast, complete disassembly of fuel occurs. The fusion reaction least difficult to achieve combines a deuteron (the nucleus of the deuterium atom) with a triton (the nucleus of a tritium atom). Both nuclei are isotopes of the hydrogen nucleus and contain a single unit of positive electric charge. Deuterium-tritium (D-T) fusion requires the nuclei to have lower kinetic energy than is needed for the fusion of more highly charged heavier nuclei. The two products of the reaction are an alpha particle (nucleus of the helium atom) at an energy of 3.5 million electron volts (MeV) and a neuron at an energy of 14.1 MeV. (One MeV is the energy equivalent of 10 billion Kelvin.). The neutrons, lacking electric charge, is not affected by electric or magnetic fields within the plasma and can escape the plasma to deposit its energy in a material,...
