Direct-drive heavy ion beam inertial confinement fusion: a review, toward our future energy source

Abstract

Direct-drive heavy ion beam (HIB) inertial confinement fusion (ICF), or HIF would be a promising future energy source for society. Particle accelerators produce HIBs with precise particle energies, pulse lengths and pulse shapes with high energy efficiencies of ~30-40%. Higher energy driver efficiency means that a lower fusion energy output is required to construct a HIF power station to supply ~1 GW of electricity. A HIF power station could use about 4 to 5 MJ of HIB energy per shot at a shot rate of ~10 Hz. This review is focused on the direct-drive scheme in HIF. In direct-drive fuel target HIBs deposit their energy into a shell surrounded by a denser tamping outer layer. The DT (Deuterium-Tritium) fusion fuel, with a total mass of several mg, must be compressed to about one thousand times solid density to reduce the input driver energy and to achieve an adequate burn fraction. High-density compression is a major challenge in ICF, requiring that non-uniformity in driver energy deposition be kept lower than a few percent. The axis of an HIB can be made to oscillate sufficiently rapidly to improve the uniformity of energy deposition.