Optimisation of the yield of low-threshold nuclear reactions under the action of protons accelerated using a terawatt femtosecond laser

Abstract: The possibility of performing nuclear reactions with a low energy threshold using terawatt femtosecond laser systems is considered by the example of the reactions ¹¹B(p, α)2α and ⁷Li(p, n)⁷Be used for neutronless thermonuclear fusion and obtaining neutron beams. Based on the literature data on the dependences of the average energy and cutoff energy in the spectrum of laser-accelerated protons on the laser radiation intensity and laser pulse energy, we estimate the expected number of recorded events depending on the laser radiation intensity in the intensity range achievable for compact desktop terawatt laser systems. It is shown that the optimal intensities for observing the reactions in question lie in the range (1–5)×10¹⁹ W·cm^-2, while the total number of secondary particles per 1 TW of peak power can reach 10⁶ and 10⁸ for reactions ¹¹B(p, α)2α and ⁷Li(p, n)⁷Be, respectively.

Keywords: terawatt laser system, femtosecond laser pulses, relativistic intensity, electron and ion acceleration, nuclear reactions, ¹¹B(p, α)2α and ⁷Li(p, n)⁷Be, neutronless thermonuclear reaction, directed neutron beam.