Expansion of nanoplasmas and laser-driven nuclear fusion in single exploding clusters

TL;DR

This paper investigates how laser pulse shaping influences nanoplasma expansion regimes in clusters, enabling controlled Coulomb explosions and enhancing intracluster nuclear fusion through hybrid expansion schemes.

Contribution

It introduces a self-consistent kinetic model and a double-pump irradiation scheme to control cluster expansion and fusion processes, supported by molecular dynamics simulations.

Findings

Double-pump scheme produces hybrid expansion regimes.

Hybrid regimes enable intracluster fusion reactions.

Ion overtaking leads to multiple ion flows with different velocities.

Abstract

The expansion of laser-irradiated clusters or nanodroplets depends strongly on the amount of energy delivered to the electrons and can be controlled by using appropriately shaped laser pulses. In this paper, a self-consistent kinetic model is used to analyze the transition from quasineutral, hydrodinamic-like expansion regimes to the Coulomb explosion (CE) regime when increasing the ratio between the thermal energy of the electrons and the electrostatic energy stored in the cluster. It is shown that a suitable double-pump irradiation scheme can produce hybrid expansion regimes, wherein a slow hydrodynamic expansion is followed by a fast CE, leading to ion overtaking and producing multiple ion flows expanding with different velocities. This can be exploited to obtain intracluster fusion reactions in both homonuclear deuterium clusters and heteronuclear deuterium-tritium clusters, as also proved by three-dimensional molecular-dynamics simulations.