Abstract
Using several-mJ energy pulses from a high-repetition rate (1/2 kHz), ultrashort (35 fs) pulsed laser interacting with a ∼10 μm 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 1019 W/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 d(d,n)3He 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.
Accepted Version (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call