The Established Paradigm: D+T Fusion At very high temperatures found only in stars and in exploding fission bombs, Deuterium (D), Tritium (T), or light Helium (3He) will fuse in various combinations and produce larger nuclei and excess heat. The U.S. Government has investigated these and less promising reactions since 1951 through large research grants to major physics research labs. Most of the effort has been aimed at the D + T reaction because this fusion reaction requires the lowest temperature to sustain (10,000,000 degrees Kelvin). There is a considerable interest in the D + 3He fusion reaction because it produces few neutrons as a byproduct of the main reaction and therefore presents fewer problems with radioactive waste. 3He is extremely rare on Earth but could be obtained on the Moon where 3He residue from the solar wind has accumulated in the top few inches of soil since the moon was formed, or from other celestial bodies. The theoretical temperature of fusion for a D + 3He reaction is about five times higher than for the D + T reaction. D + D fusion produces neutrons but the fuel (D2 from heavy water) is easily obtainable from water. The theoretical temperature for such a reaction in plasma is about three times higher than for D + T fusion. This leads to the practical problem assumed to be readily soluble, that the as yet undesigned 3He + D reactor will have uniform conditions throughout so as to suppress the undesirable D + D reaction. At a 1989 International Astronautic Federation conference, (previously covered in Space Power), the assertion was made in a NASA presentation that D + 3He fusion was commercially promising and that this reaction provided a economic justification for a mining base on the moon. Many scientists at the conference were critical of this assertion. 1. "Fusion is the energy of the future and always will be" (A British physicist with a major lab). According to NASA literature demonstration reactors for D + T fusion are planned "after 2015," and the "facilities required for both magnetic and inertial confinement will be large and expensive."4 D + 3He is probably much farther away from commercially viable use. 2. Dr. Andrew Cutler, Editor of Space Power, felt that if the higher temperatures really weren't a problem and a clean reaction was needed going to a still higher temperatures with a Boron fusion reaction which emits no neutrons made more sense. Boron is easily obtainable on Earth. Looking at this objection further it would seem to be crushing. The main Boron fusion reaction under study has been the p - nB cycle which yields three Helium nuclei and no neutrons plus 8.66 Million Electron Volts (MeV) of energy [Ibid 4]. According to the NASA 1988 report, the problems of going from temperatures of 10 keV for D + T fusion to about 50 KeV for D + 3He Fusion is "not worth mentioning." [Ibid, p. 215, 4] Boron plus a proton requires slightly higher temperatures to achieve fusion and has all the advantages of the clean 3He reaction. It also doesn't have the side reaction that D + D and D + 'He have which produce neutrons and therefore radioactive waste.
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