Thermal and chaotic distributions of plasma in laser driven Coulomb explosions of deuterium clusters

Abstract

In this work we explore the possibility that the motion of the deuterium ions emitted from Coulomb cluster explosions is chaotic enough to resemble thermalization. We analyze the process of nuclear fusion reactions driven by laser-cluster interactions in experiments conducted at the Texas Petawatt laser facility using a mixture of D2+3He and CD4+3He cluster targets. When clusters explode by Coulomb repulsion, the emission of the energetic ions is nearly isotropic. In the framework of cluster Coulomb explosions, we analyze the energy distributions of the ions using a Maxwell- Boltzmann (MB) distribution, a shifted MB distribution (sMB) and the energy distribution derived from a log-normal (LN) size distribution of clusters. We show that the first two distributions reproduce well the experimentally measured ion energy distributions and the number of fusions from d-d and d-3He reactions. The LN distribution is a good representation of the ion kinetic energy distribution well up to high momenta where the noise becomes dominant, but overestimates both the neutron and the proton yields. If the parameters of the LN distributions are chosen to reproduce the fusion yields correctly, the experimentally measured high energy ion spectrum is not well represented. We conclude that the ion kinetic energy distribution is highly chaotic and practically not distinguishable from a thermalized one.

arXiv comment9 pages, 6 figures

References in corpus (10)

• Laser-driven nonlinear cluster dynamics
• Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma
• Novel path towards compact laser ion accelerators for hadron therapy: Tenfold energy increase in laser-driven multi-MeV ion generation using a gas target mixed with submicron clusters
• Measurement of the plasma astrophysical S factor for the 3He(D, p)4He reaction in exploding molecular clusters
• Temperature measurements of fusion plasmas produced by petawatt laser-irradiated D2-3He or CD4-3He clustering gases
• Comment on "Observation of neutronless fusion reactions in picosecond laser plasmas"
• Model-independent determination of the astrophysical S-factor in laser-induced fusion plasmas
• Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases
• Chaos driven fusion enhancement factor at astrophysical energies
• Gamow peak approximation near strong resonances