Effects of cluster size and spatial laser intensity distribution on fusion neutron generation by laser driven Deuterium clusters

A three dimensional molecular dynamic code is used to study the generation of fusion neutrons from Coulomb explosion of Deuterium clusters driven by intense near infra-red (NIR) laser ($\lambda=800nm$) of femtosecond pulse duration ($\tau=50 fs$) under beam-target interaction scheme. We have considered various clusters of average sizes ($\langle R_0\rangle$=80,140,200\AA) which are irradiated by a laser of peak spatial-temporal intensity of 1$\times10^{18} W/cm^{2}$. The effects of cluster size and spatial laser intensity distribution on ion energies due to the Coulomb explosion of the cluster are included by convolution of single cluster single intensity ion energy distribution function (IEDF) over a range of cluster sizes and laser intensities. The final convoluted IEDF gets broadened on both lower and higher energy sides due to this procedure. Furthermore, the neutron yield which takes into account the convoluted IEDF, also gets modified by a factor of $\sim$2 compared to the case when convolution effects are ignored.