The supply of the required energy to achieve the fuel ignition is one of great concern in a fusion reactor. High amount of energy is needed for the ignition of He-3-He-3 fuel in a fusion reactor which is due to the losses of radiation and the requirement for high-temperature electrons and ions. The fast ignition (FI) approach causes a decrease in the laser power required to reach a large energy gain in an inertial confinement fusion (ICF) reactor. Ions have the benefit of having classical interaction through Coulomb dispersion with the background plasma. In this method, it is suggested to use deuteron beam for decreasing the ignition energy of the He-3-He-3 fuel. The deuteron particles would fuse with ions into fuel (helium-3) and produce additional energy. This excess energy has a considerable role in increasing energy gain in an He-3-He-3 fusion reactor. In this paper, the value of the energy efficiency coefficient (Y-value) and the total deposited energy are computed at different deuteron beam energy and electron temperature. The results show that Y-value is independent of helium-3 numerical density in the He-3-He-3 plasma and increases slowly with an increase in ion temperature. This fact is substantial at little deuteron energy and high electron temperature. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.