Laser-driven acceleration of ion beams for high-gain inertial confinement fusion

Abstract

Inertial confinement fusion (ICF) is currently one of the two main paths towards an energy source based on thermonuclear fusion. A promising ICF option is ion fast ignition (IFI), in which the ignition of nuclear fuel is initiated by an intense laser-driven ion beam. This paper presents the results of systematic numerical (particle-in-cell) studies of the properties of laser-driven carbon ion beams produced under conditions relevant for IFI, and the feasibility of achieving beam parameters required for fuel ignition is discussed. It was found that a 1 ps 200 kJ infrared laser driver is capable of producing ion beams with parameters required for IFI, even with a simple non-optimised target, but only at small distances (⩽0.1 mm) from the target. At such distances, the beam intensity and fluence exceeds 5 × 1021 W cm−2 and 2 GJ cm−2, respectively, while the beam energy approaches 30 kJ. The ion beam parameters can be significantly improved by carefully selecting the target thickness and shape. However, even with an optimised target, achieving the beam parameters required for IFI is possible only at distances from the target below 0.5 mm. The ion acceleration is accompanied by the emission of powerful (⩾50 PW) pulses of short-wavelength synchrotron radiation which are the source of significant ion energy losses and may pose a threat to the fusion infrastructure. In addition to ICF, the extremely intense ion beams demonstrated in the paper can be a unique research tool for research in nuclear physics, high energy-density physics or materials science.