Two-Plasmon-Decay Instability Stimulated by a Normal- and Large-Angle-Incidence Laser Pair

TL;DR

This study investigates the two-plasmon-decay instability driven by combined normal- and large-angle laser beams in inertial confinement fusion, revealing low-threshold growth and significant energy transfer effects through particle-in-cell simulations.

Contribution

It demonstrates that combined laser beams can induce TPD at lower intensities than previously known, highlighting a new seed-amplification mechanism in laser-plasma interactions.

Findings

TPD can grow at unexpectedly low laser intensities with combined beams.

Both laser beams contribute to TPD growth via seed-amplification.

Significant pump depletion and hot electron generation occur due to TPD.

Abstract

The two-plasmon-decay instability (TPD) is a critical target preheating risk in direct-drive inertial confinement fusion. In this paper, TPD collectively driven by a normal-incidence laser beam (Beam-N) and a large-angle-incidence laser beam (Beam-L) is investigated via particle-in-cell simulations. Significant TPD growth is found able to develop in this regime at previously unexpected low laser intensities if the intensity of Beam-L exceeds the large-angle-incidence threshold. Both beams contribute to the growth of TPD in a "seed-amplification" manner where the absolute instability driven by Beam-L provides the seeds that get convectively amplified by Beam-N, making TPD energetically important and causing significant pump depletion and hot electron generation.