Fast ignition of fusion targets by laser-driven electrons

TL;DR

This paper uses hybrid PIC simulations to study how laser-driven electrons can ignite fusion targets, considering magnetic effects, plasma response, and recent experimental findings, to optimize electron beam parameters for efficient ignition.

Contribution

It introduces comprehensive hybrid PIC simulations that incorporate magnetic effects and plasma dynamics to analyze fast electron transport and fusion target ignition, advancing understanding of optimal conditions.

Findings

Beam collimation significantly lowers ignition energy requirements.

Increased electron beam divergence impacts ignition success.

Target ignition depends on electron energy, divergence, and geometry.

Abstract

We present hybrid PIC simulations of fast electron transport and energy deposition in pre-compressed fusion targets, taking full account of collective magnetic effects and the hydrodynamic response of the background plasma. Results on actual ignition of an imploded fast ignition configuration are shown accounting for the increased beam divergence found in recent experiments [J.S. Green et al., Phys. Rev. Lett. 100, 015003 (2008)] and the reduction of the electron kinetic energy due to profile steepening predicted by advanced PIC simulations [B. Chrisman et al. Phys. Plasmas 15, 056309 (2008)]. Target ignition is studied as a function of injected electron energy, distance of cone-tip to dense core, initial divergence and kinetic energy of the relativistic electron beam. We found that beam collimation reduces substantially the ignition energies of the cone-guided fuel configuration assumed here.