Effect of resistivity gradient on laser-driven electron transport and ion acceleration

Abstract

The effect of resistivity gradient on laser-driven electron transport and ion acceleration is investigated using collisional particle-in-cell simulation. The study is motivated by recent proton acceleration experiments [Gizzi et al., Phys. Rev. ST Accel. Beams 14, 011301 (2011)], which showed significant effect of the resistivity gradient in layered targets on the proton angular spread. This effect is reproduced in the present simulations. It is found that resistivity-gradient generation of magnetic fields and inhibition of electron transport is significantly enhanced when the feedback interaction between the magnetic field and the fast-electron current is included. Filamentation of the laser-generated hot electron jets inside the target, considered as the origin of the nonuniform proton patterns observed in the experiments, is clearly suppressed by the resistive magnetic field. As a result, the electrostatic sheath field at the target back surface acquires a relatively smooth profile, which contributes to the superior quality of the proton beams accelerated off layered targets in the experiments. V C 2013 AIP Publishing LLC. [http://dx.

Effects of buried high-Z layers on fast electron propagation

“…The term magnetic field refers to the total magnetic field hereafter. Strong resistive magnetic fields generated at the interface of different materials have been observed in recent collisional PIC simulations [38,39], which have a similar magnetic field distribution and magnitude as our results. The Larmor radius of the fast electrons in the magnetic field region would become very small as the magnetic field is large.…”

Nanoscale femtosecond imaging of transient hot solid density plasmas with elemental and charge state sensitivity using resonant coherent diffraction

“…This is intimately intertwined with the ionization dynamics and the complex evolution of the bulk return currents [8,9]. These are important due to the strong magnetic and electric fields generated at these current densities, up to 10 5 T and 10 14 V/m, as well as the rapid temporal and spatial evolution of the bulk temperature, ionization state, and hence resistivity by virtue of the electron-ion collision frequency, and anomalous resistivity from strong fields [5][6][7][8][9][10]. At present, a predictive understanding of high-intensity laser-matter interactions is severely hampered by the lack of self-consistent models for the ionization and recombination dynamics, coupled with the complex electron transport and collisions, and our inability to unravel this complexity with available experimental techniques in laser-only experiments.…”

“…One of the essential elements in the generation of transient hot solid-density plasmas by ultra-high intensity (UHI) lasers is the relativistic electron generation [1][2][3] and transport dynamics [3][4][5][6][7]. Near the laser focus, the current density of the relativistic electrons can exceed 10 13 A/cm 2 [3].…”

Manipulation and optimization of electron transport by nanopore array targets

“…Fast electrons generated by ultra-intense laser interacting with solid targets have wide applications in microfocus x-ray source [1], positron generation [2], ion acceleration [3] and inertial confinement fusion [4]. However, the self-induced Weibel instability [5] and filamentation [6] during the transport process may inevitably be detrimental to beam divergence and directionality, leading to reduced yield and degenerated beam quality.…”