High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

Hah, J. and Petrov, G.M. and Nees, J.A. and He, Z.-H. and Hammig, M.D. and Krushelnick, K. and Thomas, A.G.R. (2016) High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O. Applied Physics Letters, 109 (14). ISSN 0003-6951

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Using several-mJ energy pulses from a high-repetition rate (1/2 kHz), ultrashort (35 fs) pulsed laser interacting with a 10 lm diameter stream of free-flowing heavy water (D2O), we demonstrate a 2.45 MeV neutron flux of 105/s. Operating at high intensity (of order 1019W/cm2), laser pulse energy is efficiently absorbed in the pre-plasma, generating energetic deuterons. These collide with deuterium nuclei in both the bulk target and the large volume of low density D2O vapor surrounding the target to generate neutrons through dðd; nÞ3 He reactions. The neutron flux, as measured by a calibrated neutron bubble detector, increases as the laser pulse energy is increased from 6 mJ to 12 mJ. A quantitative comparison between the measured flux and the results derived from 2D-particle-in-cell simulations shows comparable neutron fluxes for laser characteristics similar to the experiment. The simulations reveal that there are two groups of deuterons. Forward moving deuterons generate deuterium–deuterium fusion reactions in the D2O stream and act as a point source of neutrons, while backward moving deuterons propagate through the low-density D2O vapor filled chamber and yield a volumetric source of neutrons.

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Journal Article
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Applied Physics Letters
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Copyright 2016 American Institute of Physics. The following article appeared in Applied Physics Letters, 109,14, 2016 and may be found at http://dx.doi.org/10.1063/1.4963819 This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
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11 Nov 2016 09:02
Last Modified:
27 Sep 2020 03:33