.5 MeV + p + B11 -> 3 He⁴ + 8.7 MeV
A trove of technical articles regarding the proton-boron fusion reaction:
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I guess the "p-B11 fusion" energy concept is termed fusion because the first step is fusing a proton with a boron11 to create boron12. This of course consumes energy.
Because boron12 is unstable a cascade of "fission" nuclear reactions follow, and this ultimately leads to the production of various smaller sized nuclei - such as helium 4 (alpha particles). This can result in net release of energy.
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How can it be that B11, a stable isotope, can undergo fusion/fission and give a net gain of energy?
B11 is an oddball. It has a particularly weakly bound nucleus (making it similar to a radioactive isotope) but is a stable isotope nonetheless. Its nucleus has a particularly high energy level - which is attributable a cosmic ray that, in the distant past, led to its creation from B10 or other elements (see the x-process below). In the p-B11 fusion process, after being hit by a 500 keV proton, B11 is transmuted to B12. The unstable B12 quickly breaks up and yields three He4 atoms. With this decay there is a sizable release of energy (originating from the aforementioned cosmic ray), and there is no neutron radiation.
The existence of abundant B11 is due to its creation by the x-process.
Cosmic ray spallation, also known as the x-process, is a set of naturally occurring nuclear reactions causing nucleosynthesis; it refers to the formation of chemical elements from the impact of cosmic rays on an object. Cosmic rays are highly energetic charged particles from beyond Earth, ranging from protons, alpha particles, and nuclei of many heavier elements.The x-process in cosmic rays is the primary means of nucleosynthesis for the five stable isotopes of lithium, beryllium, and boron.[2] As the proton–proton chain reaction cannot proceed beyond 4He due to the unbound nature of 5He and 5Li,[3] and the triple alpha process skips over all species between 4He and 12C, these elements are not produced in the main reactions of stellar nucleosynthesis. In addition, nuclei of these elements are relatively weakly bound, resulting in their rapid destruction in stars and no significant accumulation. It was thus postulated that another nucleosynthesis process occurring outside stars was necessary to explain their existence in the universe. This process is now known to occur in cosmic rays, where lower temperature and particle density favor reactions leading to the synthesis of lithium, beryllium, and boron.[2]
Bottom line - B11 exists in abundance because of the x-process by which it was created. And when a proton and a B11 atom are put into the right high energy environment they can be transmuted into three He4 atoms and create energy.
For this idea to be viable for providing low cost energy generation one only need develop an efficient and low cost process for generating a million-billion-billion 0.5 MeV protons per second and colliding them with a million-billion-billion B11 atoms per second to create a million-billion-billion B12 atoms per second that then decay to He4 atoms The nuclear energy released by this scale of operation would be 364 Megawatts
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0.5 MeV + p + B11 -> 3 He⁴ + 8.7 MeV
left hand side mass = 1.00727 AMU + 11.009306 AMU= 12.0166 AMUright hand side mass = 3*4.002603 AMU= 12.007809 AMUnet change in mass = -.0088 AMUythe energy equivalent (-.0088 AMU x 931 MeV/AMU) is 8.2 MeV net energy
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Boron is synthesized entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, so it is a low-abundance element in the Solar System and in the Earth's crust.[10] It constitutes about 0.001 percent by weight of Earth's crust.[11]
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