STM-D-0792Paper2017Designed, not yet built

Road map to clean energy using laser beam ignition of boron-hydrogen fusion

H. Hora · S. Eliezer · G.J. Kirchhoff · N. Nissim · J.X. Wang · P. Lalousis · Y.X. Xu · G.H. Miley · J.M. Martinez-Val · W. McKenzie · J. Kirchhoff

Abstract and summary · read the original at the source

In one page

Heinrich Hora and ten colleagues set out the engineering road map for the fusion fuel that returns charged particles instead of neutrons. Hydrogen fused with boron-11 yields three helium nuclei and nothing radioactive, which is why the site keeps coming back to it — but at ordinary thermal-equilibrium conditions it is about a hundred thousand times harder to ignite than deuterium and tritium. Hora’s route around that is to stop heating the fuel at all. A picosecond laser pulse of petawatt power pushes a solid-density plasma block forward by the light’s own pressure, reaching accelerations above ten to the twentieth centimetres per second squared, and the ignition threshold computed that way comes out about the same for boron as for deuterium–tritium. A second, longer laser pulse wraps the cylindrical fuel in a magnetic field of several kilotesla to hold the reaction together. Their design: fourteen milligrams of fuel, one gigajoule a shot, and the alpha particles converted straight to electricity.

Why it matters hereChapter twelve’s argument is that aneutronic fusion is the fuel that matters, because it hands you charged particles you can convert directly rather than neutrons you have to shield and that make the reactor radioactive. This is the paper that turns that preference into a reactor with numbers on it — laser powers, field strengths, a fuel mass and a shot rate — and names the measurement that tells you whether your laser is good enough to try.

What it claims

01Hydrogen fused with boron-11 produces three alpha particles and no neutrons, which is what makes it the one fusion fuel free of radioactive waste; the reaction has been known since Oliphant and Rutherford in 1933, and stays neutron-free as long as the reacting proton energies remain below the MeV range.Sect. 2, opening paragraphs; Eq. (1) and Fig. 8
Settled physics
02The ignition is non-thermal. A picosecond laser pulse at ten to the eighteenth watts per square centimetre drives plasma blocks by the nonlinear ponderomotive force rather than by heating, reaching accelerations above ten to the twentieth centimetres per second squared — about a hundred thousand times higher than any acceleration previously measured in a laboratory. Predicted by computation in 1978, it was measured by Sauerbrey in 1996 from the blue Doppler shift of the reflected light and repeated by Földes and colleagues in 2000.Sect. 3, Figs. 4 and 5
Published and peer-reviewed
03When the block-ignition calculation is applied to boron-hydrogen using its measured cross-sections, the threshold comes out close to the deuterium–tritium value — five orders of magnitude better than boron-hydrogen ignition at thermal equilibrium, which is the result the whole road map rests on.Sect. 3, paragraph beginning ‘It was then a surprise’
Published and peer-reviewed
04The reaction multiplies itself. Each event’s three alphas hand their energy on by elastic nuclear collisions to cold boron and hydrogen nuclei in the strongly non-equilibrium plasma, producing an avalanche; the effect was worked out against the measured high-gain boron experiments of Picciotto and of Margarone, later increased by a further factor of ten by Giuffrida and colleagues.Sect. 3, closing paragraphs; Fig. 8
Published and peer-reviewed
05The proposed reactor is fully specified: cylindrical fuel inside a laser-driven capacitor-coil target, where a kilojoule nanosecond pulse raises a magnetic field of several kilotesla to trap the plasma at about one millimetre radius, and a second pulse of 30 kilojoules in a picosecond — 30 petawatts — ignites it end-on. Fourteen milligrams of fuel yields more than one gigajoule, about 300 kilowatt-hours, per shot, inside a steel sphere of at least one metre radius, with a mechanical shock equivalent to roughly 50 grams of chemical explosive. Because the products are charged, holding the Faraday-screened unit at a negative potential just below the alphas’ stopping voltage decelerates them electrostatically and the recovered energy is converted with established high-voltage direct-current technique, avoiding a thermal cycle — provided discharge losses to the reactor wall stay small.Sect. 2, Figs. 2 and 3; Sect. 3, final paragraph
Designed, not yet built
06The named go or no-go test for any laboratory attempting this is the pulse contrast ratio: light reflected from the target must show a blue Doppler shift of its spectral lines. Repeat attempts that used lasers of insufficient contrast returned a red shift instead and did not reproduce the block acceleration, so the shift is the check to run before anything else.Sect. 5
What to watch

Read it · abstract

Abstract

With the aim to overcome the problems of climatic changes and rising ocean levels, one option is to produce large-scale sustainable energy by nuclear fusion of hydrogen and other very light nuclei similar to the energy source of the sun. Sixty years of worldwide research for the ignition of the heavy hydrogen isotopes deuterium (D) and tritium (T) have come close to a breakthrough for ignition. The problem with the DT fusion is that generated neutrons are producing radioactive waste. One exception as the ideal clean fusion process – without neutron production – is the fusion of hydrogen (H) with the boron isotope 11B11 (B11). In this paper, we have mapped out our research based on recent experiments and simulations for a new energy source. We suggest how HB11 fusion for a reactor can be used instead of the DT option. We have mapped out our HB11 fusion in the following way: (i) The acceleration of a plasma block with a laser beam with the power and time duration of the order of 10 petawatts and one picosecond accordingly. (ii) A plasma confinement by a magnetic field of the order of a few kiloteslas created by a second laser beam with a pulse duration of a few nanoseconds (ns). (iii) The highly increased fusion of HB11 relative to present DT fusion is possible due to the alphas avalanche created in this process. (iv) The conversion of the output charged alpha particles directly to electricity. (v) To prove the above ideas, our simulations show for example that 14 milligram HB11 can produce 300 kWh energy if all achieved results are combined for the design of an absolutely clean power reactor producing low-cost energy.

Keywords: Clean boron fusion; Laser boron fusion; Non-thermal plasma block acceleration; Petawatt-picosecond laser pulses; Single laser beam ignition.

H. Hora, S. Eliezer, G.J. Kirchhoff, N. Nissim, J.X. Wang, P. Lalousis, Y.X. Xu, G.H. Miley, J.M. Martinez-Val, W. McKenzie and J. Kirchhoff. Laser and Particle Beams 35 (2017) 730–740.

(Abstract only. The complete article is at the publisher — see the rights note for why the full text is not reproduced here.)

The way in

https://doi.org/10.1017/S0263034617000799Licence checked in the article itself: the published paper, Laser and Particle Beams 35 (2017) 730–740, carries the single line ‘© Cambridge University Press, 2017’ on its first page and the running footer ‘Published online by Cambridge University Press’, and no Creative Commons statement appears anywhere in its eleven pages. So this sheet carries the summary, the claims and the authors’ own abstract and sends the reader to the source. The claims below were written from the complete published paper, and the locators use the article’s own section and figure numbering. The skeleton listed eight authors; the paper’s byline carries eleven, and all eleven are restored above. Affiliations: Theoretical Physics, University of New South Wales, Sydney; SOREQ Research Centre, Yavne; UJG Management, Poing; Polytechnique University, Madrid; Earth and Planetary Science, University of California, Berkeley; State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai; Institute of Electronic Structure and Laser FORTH, Heraklion; Nuclear, Plasma and Radiological Engineering, University of Illinois, Urbana; and HB11 Energy Pty Ltd, Sydney. Received 26 September 2017, accepted 16 October 2017.

How to cite it

H. Hora, S. Eliezer, G.J. Kirchhoff, N. Nissim, J.X. Wang, P. Lalousis, Y.X. Xu, G.H. Miley, J.M. Martinez-Val, W. McKenzie, J. Kirchhoff (2017) Road map to clean energy using laser beam ignition of boron-hydrogen fusion. doi:10.1017/S0263034617000799

Where it sits in the curriculum

Lattice confinement fusion