Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

Alejo, A. and Green, A. and Ahmed, H. and Robinson, A.P.L. and Cerchez, M. and Clarke, R. and Doria, D. and Dorkings, S. and Fernandez, J. and McKenna, P. and Mirfayzi, S.R. and Naughton, K. and Neely, D. and Norreys, P. and Peth, C. and Powell, H. and Ruiz, J.A. and Swain, J. and Willi, O. and Borghesi, M. and Kar, S. (2016) Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 829. pp. 176-180. ISSN 0168-9002

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    Abstract

    The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic number ions in fusion reactions. In addition to benefiting from the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in the neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in the neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow divergence ( 70 full width at half maximum) neutron beam recently obtained from an experiment employing multi-MeV deuteron beams of narrow divergence (upto 30 FWHM depending on the ion energy) accelerated by a subpetawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from the interactions with higher power lasers at upcoming facilities.