In search of ways to improve the properties of a laser-accelerated heavy ion beam relevant for fusion fast ignition

Abstract

Ion fast ignition (IFI) is one of the proposed options for inertial fusion in which the ignition of nuclear fuel is initiated by an intense ion beam. In this paper, the properties of a laser-accelerated heavy ion beam are investigated for the possible use of such a beam as a fuel igniter in the IFI scenario. Using a two-dimensional particle-in-cell code, detailed studies of laser-driven heavy ion acceleration were carried out to determine the possibility of improving the properties of the heavy ion beam relevant for IFI by the appropriate selection of certain laser and target parameters. In simulations, a 1-ps laser with an energy of 150–250 kJ irradiated targets with a variety of atomic mass numbers, areal densities, thicknesses, and densities. For each of the sets of laser and target parameters considered in the paper, the parameters of the heavy ion beam relevant for IFI were determined and discussed. It was found that for realistic laser driver parameters, the IFI requirements are best met by ion beams with moderate ion mass numbers (A ∼ 50–100), such as the beam of Cu ions. It was shown that by optimizing the laser focal spot, as well as by properly matching the energy and power of the laser to the target areal mass density, it is possible to significantly improve the properties of the heavy ion beam relevant for IFI and, in particular, bring a many-fold increase in the intensity, fluence, and energy of the beam.