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Title: Laser-induced Coulomb mirror effect: Applications for proton acceleration

Abstract

Using two-dimensional particle-in-cell simulations, the temporal evolution of the uncompensated charge on an ultra-thin (400 nm) foil target ionized by a relativistically intense laser pulse is studied in detail. The analysis reveals a new dynamic regime of acceleration of light ions/protons that allows particles to experience the maximum acceleration potential created by the laser. As an alternative to the conventional double-layer target, a new target geometry in which the proton energy is enhanced by {approx_equal}30% is proposed.

Authors:
; ;  [1]
  1. Department of Radiation Physics, Laser Lab, Fox Chase Cancer Center, 432 Rhawn Street, Philadelphia, Pennsylvania 19006 (United States)
Publication Date:
OSTI Identifier:
20974891
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 3; Other Information: DOI: 10.1063/1.2716690; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATION; BEAM-PLASMA SYSTEMS; FOILS; GEOMETRY; IONIZATION; LASERS; LAYERS; LIGHT IONS; LIGHT TRANSMISSION; PLASMA; PLASMA SIMULATION; PROTON BEAMS; PROTONS; PULSES; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Velchev, I., Fourkal, E., and Ma, C.-M. Laser-induced Coulomb mirror effect: Applications for proton acceleration. United States: N. p., 2007. Web. doi:10.1063/1.2716690.
Velchev, I., Fourkal, E., & Ma, C.-M. Laser-induced Coulomb mirror effect: Applications for proton acceleration. United States. doi:10.1063/1.2716690.
Velchev, I., Fourkal, E., and Ma, C.-M. Thu . "Laser-induced Coulomb mirror effect: Applications for proton acceleration". United States. doi:10.1063/1.2716690.
@article{osti_20974891,
title = {Laser-induced Coulomb mirror effect: Applications for proton acceleration},
author = {Velchev, I. and Fourkal, E. and Ma, C.-M.},
abstractNote = {Using two-dimensional particle-in-cell simulations, the temporal evolution of the uncompensated charge on an ultra-thin (400 nm) foil target ionized by a relativistically intense laser pulse is studied in detail. The analysis reveals a new dynamic regime of acceleration of light ions/protons that allows particles to experience the maximum acceleration potential created by the laser. As an alternative to the conventional double-layer target, a new target geometry in which the proton energy is enhanced by {approx_equal}30% is proposed.},
doi = {10.1063/1.2716690},
journal = {Physics of Plasmas},
number = 3,
volume = 14,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • The results of studies of high-intensity proton beam generation from thin (1-3 {mu}m) solid targets irradiated by 0.35 ps laser pulse of energy up to 15 J and intensity up to 2x10{sup 19} W/cm{sup 2} are reported. It is shown that the proton beams of terawatt power and intensity around 10{sup 18} W/cm{sup 2} at the source can be produced when the laser-target interaction conditions approach the skin-layer ponderomotive acceleration requirements. The proton beam parameters remarkably depend on the target structure and can be significantly increased with the use of a double-layer Au/PS target (plastic covered by 0.1-0.2 {mu}m Aumore » front layer)« less
  • The regime of multicascade proton acceleration during the interaction of a 10{sup 21}-10{sup 22} W/cm{sup 2} laser pulse with a structured target is proposed. The regime is based on the electron charge displacement under the action of laser ponderomotive force and on the effect of relativistically induced slab transparency which allows realization of the idea of multicascade acceleration. It is shown that a target comprising several thin foils properly spaced apart can optimize the acceleration process and give at the output a quasi-monoenergetic beam of protons with energies up to hundreds of MeV with an energy spread of just amore » few percent.« less
  • The acceleration of protons in dense plastic foils irradiated by ultrahigh intensity laser pulses is simulated using a two-dimensional hybrid particle-in-cell scheme. For the chosen parameters of the overdense foils of densities {rho}=0.2, 1, and 3 g/cm{sup 3} and of an ultrahigh intensity (2x10{sup 20} W/cm{sup 2}) laser pulse, our simulations illustrate that a high-density target is favorable to high collimation of the target-normal-sheath acceleration protons but less energy for a short acceleration time (<100 fs). In particular, the difference of strong local heating of the carbon ion for different plasma densities is clearly observed at both the front andmore » rear surfaces of thin solid targets, suggesting that the effect of the density and composition of the targets are also important for correctly simulating energetic ion generation in ultraintense laser-solid interactions.« less
  • Laser-driven ion acceleration has been experimentally investigated by irradiating, with tightly focused femtosecond laser pulses at 5x10{sup 19} W/cm{sup 2}, thin metal foils, which have been back-coated with a {mu}m thick dielectric layer. The observation we report shows the production of MeV proton bunches with an unexpected highly uniform spatial cross section.
  • The interactions of ultraintense circularly polarized laser pulses with a mixed solid target and a double-layer target are studied by two-dimensional particle-in-cell simulations. Different carbon and proton compositions in the targets are used in the simulations. It is shown that the proton acceleration mechanisms in both targets are very sensitive to the ion density ratios between protons and carbon ions. For a mixed solid target, a relatively low proton density gives rise to monoenergetic peaks in the proton energy spectrum while a high proton density leads to a large cut-off energy and wide energy spread. With the increase of themore » ratio, the so-called directed-Coulomb-explosion becomes dominated over the radiation pressure. Surprisingly, for a double-layer target with a front proton layer and an ultrathin rear carbon layer, a highly monoenergetic proton beam with a peak energy of 1.7 GeV/u, an energy spread of {approx}4%, and a divergency angle of 2 Degree-Sign can be obtained, which might have diverse applications in medical therepy and proton imaging in future.« less