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Title: Focusing of high-current laser-driven ion beams

Abstract

Using a two-dimensional relativistic hydrodynamic code, it is shown that a dense high-current ion beam driven by a short-pulse laser can be effectively focused by curving the target front surface. The focused beam parameters essentially depend on the density gradient scale length of the preplasma L{sub n} and the surface curvature radius R{sub T}. When L{sub n}{<=}0.5{lambda}{sub L} ({lambda}{sub L} is the laser wavelength) and R{sub T} is comparable with the laser beam aperture d{sub L}, a significant fraction of the accelerated ions is focused on a spot much smaller than d{sub L}, which results in a considerable increase in the ion fluence and current density. Using high-contrast multipetawatt picosecond laser pulses of relativistic intensity ({approx}10{sup 20} W/cm{sup 2}), focused ion (proton) current densities approaching those required for fast ignition of DT fuel seem to be feasible.

Authors:
;  [1]
  1. Institute of Plasma Physics and Laser Microfusion, EURATOM Association, Warsaw 00-908 (Poland)
Publication Date:
OSTI Identifier:
20960204
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 15; Other Information: DOI: 10.1063/1.2721394; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 07 ISOTOPES AND RADIATION SOURCES; BEAM-PLASMA SYSTEMS; CURRENT DENSITY; FOCUSING; ION BEAMS; LASERS; PLASMA; PLASMA DENSITY; PLASMA SIMULATION; PULSES; RELATIVISTIC RANGE; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Badziak, J., and Jablonski, S.. Focusing of high-current laser-driven ion beams. United States: N. p., 2007. Web. doi:10.1063/1.2721394.
Badziak, J., & Jablonski, S.. Focusing of high-current laser-driven ion beams. United States. doi:10.1063/1.2721394.
Badziak, J., and Jablonski, S.. Mon . "Focusing of high-current laser-driven ion beams". United States. doi:10.1063/1.2721394.
@article{osti_20960204,
title = {Focusing of high-current laser-driven ion beams},
author = {Badziak, J. and Jablonski, S.},
abstractNote = {Using a two-dimensional relativistic hydrodynamic code, it is shown that a dense high-current ion beam driven by a short-pulse laser can be effectively focused by curving the target front surface. The focused beam parameters essentially depend on the density gradient scale length of the preplasma L{sub n} and the surface curvature radius R{sub T}. When L{sub n}{<=}0.5{lambda}{sub L} ({lambda}{sub L} is the laser wavelength) and R{sub T} is comparable with the laser beam aperture d{sub L}, a significant fraction of the accelerated ions is focused on a spot much smaller than d{sub L}, which results in a considerable increase in the ion fluence and current density. Using high-contrast multipetawatt picosecond laser pulses of relativistic intensity ({approx}10{sup 20} W/cm{sup 2}), focused ion (proton) current densities approaching those required for fast ignition of DT fuel seem to be feasible.},
doi = {10.1063/1.2721394},
journal = {Applied Physics Letters},
number = 15,
volume = 90,
place = {United States},
year = {Mon Apr 09 00:00:00 EDT 2007},
month = {Mon Apr 09 00:00:00 EDT 2007}
}
  • We report on measurements of the focusing of high-current, large-area beams of heavy metal ions using an electrostatic plasma lens. Tantalum ion beams were formed by a repetitively pulsed vacuum arc ion source, with energy in the 100 keV range, current up to 0.5 A, initial beam diameter 10 cm, and pulse length 250 {mu}s. The plasma lens was of internal diameter 10 cm and length 20 cm, and had nine electrostatic ring electrodes with potential applied to the central electrode of up to 7 kV, in the presence of a pulsed magnetic field of up to 800 G. Themore » current-density profile of the downstream, focused, ion beam was measured with a radially moveable, magnetically suppressed, Faraday cup. The tantalum ion-beam current density at the focus was compressed by a factor of up to 30. The results are important in that they provide a demonstration of a means of manipulating high-current ion beams without associated space-charge blowup. {copyright} {ital 1999 American Institute of Physics.}« less
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  • An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 10{sup 16}-10{sup 19} W/cm{sup 2}. The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generationmore » ion sources to be employed in medicine, nuclear physics, matter physics, and industry.« less
  • The response of the magnetized plasma in an axisymmetric, plasma-filled, solenoidal magnetic lens, to intense light ion beam injection is studied. The lens plasma fill is modeled as an inertialess, resistive, electron magnetohydrodynamic (EMHD) fluid since characteristic beam times {tau} satisfy 2{pi}/{omega}{sub {ital pe}},2{pi}/{Omega}{sub {ital e}}{lt}{tau}{le}2{pi}/{Omega}{sub {ital i}} ({omega}{sub {ital pe}} is the electron plasma frequency and {Omega}{sub {ital e},{ital i}} are the electron, ion gyrofrequencies). When the electron collisionality satisfies {nu}{sub {ital e}}{lt}{Omega}{sub {ital e}}, the linear plasma response is determined by whistler wave dynamics. In this case, current neutralization of the beam is reduced on the time scalemore » for whistler wave transit across the beam. The transit time is inversely proportional to the electron density and proportional to the angle of incidence of the beam with respect to the applied solenoidal field. In the collisional regime ({nu}{sub {ital e}}{gt}{Omega}{sub {ital e}}) the plasma return currents decay on the normal diffusive time scale determined by the conductivity. The analysis is supported by two-and-one-half dimensional hybrid particle-in-cell simulations. {copyright} {ital 1996 American Institute of Physics.}« less