Enhanced laser-driven proton acceleration via improved fast electron heating in a controlled pre-plasma

Large-amplitude plasma wave generation by laser beating in inhomogeneous magnetized plasmas

Large-amplitude plasma wave is known to accelerate electrons to high energies. The electron energy gain mainly depends on plasma wave amplitude. In this paper, we investigate the excitation of large-amplitude plasma waves by laser beat-wave in an inhomogeneous plasma. The idea behind this work is to employ linear and radial plasma density profiles to enhance the plasma wave amplitude. PIC simulations are used to validate the numerical solution of the nonlinear wave equation in cylindrical dimensions through the finite difference method. Furthermore, the effects of the quadratic-radial plasma density profiles and magnetic field on the plasma wave excitation are investigated. The study shows that compared to the linear density profile of plasma, the plasma wave amplitude in the case of a linear-radial density profile is far more pronounced. For the linear-radial density profile, the plasma wave amplitude remains steady over greater distances of propagation compared to the linear density profile, resulting in reduced immediate damping effects. It can also be seen that the plasma wave amplitude is higher for the quadratic-radial than for the linear-radial density profiles. The effect of a longitudinal magnetic field on plasma wave amplitude is investigated. It can be seen that the plasma wave amplitude is increased by applying a magnetic field. This study may provide a way to enhance the plasma wave field for accelerating the electrons in laser-plasma accelerators.

Subpicosecond pre-plasma dynamics of a high contrast, ultraintense laser-solid target interaction

Using the spectral interferometry technique, we measured subpicosecond time-resolved pre-plasma scale lengths and early expansion (<12 ps) of the plasma produced by a high intensity (6 × 10¹⁸ W/cm²) pulse with high contrast (10⁹). We measured pre-plasma scale lengths in the range of 3-20 nm, before the arrival of the peak of the femtosecond pulse. This measurement plays a crucial role in understanding the mechanism of laser coupling its energy to hot electrons and is hence important for laser-driven ion acceleration and the fast ignition approach to fusion.

Towards bright gamma-ray flash generation from tailored target irradiated by multi-petawatt laser

One of the remarkable phenomena in the laser-matter interaction is the extremely efficient energy transfer to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma $$\end{document}γ-photons, that appears as a collimated \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma $$\end{document}γ-ray beam. For interactions of realistic laser pulses with matter, existence of an amplified spontaneous emission pedestal plays a crucial role, since it hits the target prior to the main pulse arrival, leading to a cloud of preplasma and drilling a narrow channel inside the target. These effects significantly alter the process of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma $$\end{document}γ-photon generation. Here, we study this process by importing the outcome of magnetohydrodynamic simulations of the pedestal-target interaction into particle-in-cell simulations for describing the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma $$\end{document}γ-photon generation. It is seen that target tailoring prior the laser-target interaction plays an important positive role, enhancing the efficiency of laser pulse coupling with the target, and generating high energy electron-positron pairs. It is expected that such a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma $$\end{document}γ-photon source will be actively used in various applications in nuclear photonics, material science and astrophysical processes modelling.

A Few MeV Laser-Plasma Accelerated Proton Beam in Air Collimated Using Compact Permanent Quadrupole Magnets

Proton laser-plasma-based acceleration has nowadays achieved a substantial maturity allowing to seek for possible practical applications, as for example Particle Induced X-ray Emission with few MeV protons. Here we report about the design, implementation, and characterization of a few MeV laser-plasma-accelerated proton beamline in air using a compact and cost-effective beam transport line based on permanent quadrupole magnets. The magnetic beamline coupled with a laser-plasma source based on a 14-TW laser results in a well-collimated proton beam of about 10 mm in diameter propagating in air over a few cm distance.