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Nuclear Fusion
Published in D. Yogi Goswami, Frank Kreith, Energy Conversion, 2017
Although a number of different atomic nuclei can combine to release net energy from fusion, the reaction of deuterium and tritium (D-T) is the basis of planning for the first generation of fusion reactors. This choice is based on considerations of reactor economy. The D-T reaction occurs at the lowest temperature, has the highest probability for reaction, and provides the greatest output of power per unit of cost (Shannon 1989). The disadvantages of D-T as a fusion fuel are twofold. Tritium does not occur naturally in nature and must be bred in the fusion reactor or elsewhere. Second, tritium is a radioactive isotope of hydrogen with a relatively long half-life of 12.3 years. Since tritium can readily combine with air and water, special safety procedures will be required to handle the inventory necessary for a fusion reactor. There is hope that a less reactive fuel, such as deuterium alone (D-D), will eventually prove to be an economically acceptable alternative (Shannon 1989). A tantalizing alternative is the reaction between a proton and boron-11 to form three helium nuclei. This offers the prospect of aneutronic fusion, but the conditions necessary to produce energy through this reaction are very difficult to achieve (Rostoker et al. 1997).
Energetic aspects of elemental boron: a mini-review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Okan Icten, Birgul Zumreoglu-Karan
The efforts to develop nuclear fusion as usable energy were intensified at the beginning of the 21st century. Sandia National Laboratory uses the “Z-machine” to create conditions for hydrogen–boron reactions (https://www.sandia.gov/z-machine/about_z/index.html). The Z machine’s plasma has a special, reverted non-equilibrium state, in which the ion temperature is 100 times higher than electron temperature (Haeinz et al. 2006). The process, called inertial confinement fusion, distinguishes itself by using magnetic fields, rather than lasers, to compress the fuel. Sandia researchers expect to achieve infrastructure improvements of this concept within the next few years. Several private companies also support research to develop safe nuclear reactions that produce electricity directly. Lawrenceville Plasma Physics (www.lpp.fusion.com) runs theoretical and experimental programs for aneutronic p-11B fusion funded by NASA’s Jet Propulsion Laboratory and Air Force Research Laboratory (). Tri-Alpha Energy Technologies Inc. (TAE) (www.tae.com), an American company founded in 1998 to develop aneutronic fusion power, is now developing a device that will fire two balls of plasmoids into each other to fuse boron and hydrogen. Achieving a large scale private sector investment, TAE plans to commercialize the fusion-reactor technology to commercialization in the next five years (McMahon 2019).
Evaluation of Alpha Particle Emission Rate Due to the p-11B Fusion Reaction in the Large Helical Device
Published in Fusion Science and Technology, 2022
K. Ogawa, M. Isobe, H. Nuga, R. Seki, S. Ohdachi, M. Osakabe
Research on the realization of a first-generation fusion reactor has been intensively performed based on deuterium-tritium reactions. As a near-future application, self-heating of plasma using the deuterium-tritium fusion-born alpha particle has been demonstrated in ITER (Ref. 1). In a first-generation reactor, a deuterium-tritium fusion-born 14-MeV neutron is utilized for power generation.2 In addition, the study of aneutronic fusion, a fusion reaction that emits no neutron, has recently regained the spotlight. One of the most practical aneutronic fusion reactors is based on the p-11B reaction (11B(p,α)2α) (Ref. 3). The fusion cross section of p-11B has a local maximum around the incident particle energy of 135 keV (Refs. 4 and 5), as shown in Fig. 1. This local maximum corresponds to the energy level of the compound nucleus 12C, which decays to three alpha particles via α + 8Be (Ref. 6). The potential of the p-11B reaction for thermonuclear fusion reactors was investigated in magnetic confinement devices,7,8 and in particular, the Large Helical Device (LHD)–type magnetic field configuration combined with an ion cyclotron range of frequency heating.9 It was reported that the effective proton temperature needed for ignition conditions is approximately 300 keV, which is very difficult to achieve with the current technology. More realistically, a relatively high p-11B reaction rate can be achieved in boron-doped plasma using a high-energy hydrogen beam. For the feasibility of a beam fusion reactor, estimation of the p-11B reaction rate in existing plasma is important. The LHD is equipped with negative-ion-based intensive neutral beam (NB) injectors,10 whose acceleration energy is approximately 180 keV, and with an impurity powder dropper injecting boron grains into a plasma.11 Therefore, a significant p-11B fusion reaction rate could be achieved in the LHD by utilizing existing equipment. In this paper, the estimation of the p-11B fusion reaction rate in an LHD is reported for studying the spacial/energy distribution of alpha particles produced by the p-11B fusion reactions in the magnetic confinement fusion machine.