Mitigation of Two-Plasmon Decay in Direct-Drive Inertial Confinement Fusion Through the Manipulation of Ion-Acoustic- and Langmuir-Wave Damping

LLE Review, Volume 134 112 Introduction Two-plasmon decay1–6 (TPD) is a three-wave–decay instability in which an electromagnetic (EM) wave parametrically decays into two longitudinal (Langmuir) waves. Experimentally, signatures of TPD have been observed in the ionosphere7 and in laser–plasma interaction experiments.8,9 In the context of laser fusion, TPD has been identified in both the indirect-10 and direct-drive11 approaches.In these schemes, TPD is undesirable because of the anomalous absorption of laser light at densities below the critical density and the potential to accelerate electrons to high energies.12–16 High-energy electrons can preheat the target and severely degrade performance since efficient implosions require the fuel to remain on a low adiabat.