Fast ignition of a compressed inertial confinement fusion hemispherical capsule by two proton beams

A hemispherical conically guided indirectly driven inertial confinement fusion capsule has been considered. The fast ignition of the precompressed capsule driven by one or two laser-accelerated proton beams has been numerically investigated. The energy distribution of the protons is Gaussian with a mean energy of $12MeV$ and a full width at half maximum of $1MeV$⁠. A new scheme that uses two laser-accelerated proton beams is proposed. It is found that the energy deposition of $1kJ$ provided by a first proton beam generates a low-density cylindrical channel and launches a forward shock. A second proton beam, delayed by a few tens of ps and driving the energy of $6kJ$⁠, crosses the low-density channel and heats the dense shocked region where the ignition of the deuterium-tritium nuclear fuel is achieved. For the considered capsule, this new two-beam configuration reduces the ignition energy threshold to $7kJ$⁠.