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Title: Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission

Abstract

An experimental investigation of lateral electron transport in thin metallic foil targets irradiated by ultraintense ({>=}10{sup 19} W/cm{sup 2}) laser pulses is reported. Two-dimensional spatially resolved ion emission measurements are used to quantify electric-field generation resulting from electron transport. The measurement of large electric fields ({approx}0.1 TV/m) millimeters from the laser focus reveals that lateral energy transport continues long after the laser pulse has decayed. Numerical simulations confirm a very strong enhancement of electron density and electric field at the edges of the target.

Authors:
 [1];  [2]; ; ; ;  [1]; ; ;  [3];  [3];  [2]; ; ;  [4]; ;  [5]
  1. SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)
  2. (United Kingdom)
  3. CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX (United Kingdom)
  4. Department of Physics, Lund University, P.O. Box 118, S-22100 Lund (Sweden)
  5. Department of Physics and Astronomy, Queen's University Belfast, Belfast BT7 1NN (United Kingdom)
Publication Date:
OSTI Identifier:
20951212
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 14; Other Information: DOI: 10.1103/PhysRevLett.98.145001; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 43 PARTICLE ACCELERATORS; CHARGED-PARTICLE TRANSPORT; ELECTRIC FIELDS; ELECTRON DENSITY; ELECTRONS; FOILS; ION EMISSION; IRRADIATION; LASERS; PULSES; SIMULATION; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

McKenna, P., CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX, Carroll, D. C., Ledingham, K. W. D., McCanny, T., Robson, L., Clarke, R. J., Neely, D., Robinson, A. P. L., Evans, R. G., Department of Physics, Imperial College, London, SW7 2AZ, Lindau, F., Lundh, O., Wahlstroem, C.-G., Simpson, P. T., and Zepf, M. Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.145001.
McKenna, P., CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX, Carroll, D. C., Ledingham, K. W. D., McCanny, T., Robson, L., Clarke, R. J., Neely, D., Robinson, A. P. L., Evans, R. G., Department of Physics, Imperial College, London, SW7 2AZ, Lindau, F., Lundh, O., Wahlstroem, C.-G., Simpson, P. T., & Zepf, M. Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission. United States. doi:10.1103/PHYSREVLETT.98.145001.
McKenna, P., CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX, Carroll, D. C., Ledingham, K. W. D., McCanny, T., Robson, L., Clarke, R. J., Neely, D., Robinson, A. P. L., Evans, R. G., Department of Physics, Imperial College, London, SW7 2AZ, Lindau, F., Lundh, O., Wahlstroem, C.-G., Simpson, P. T., and Zepf, M. Fri . "Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission". United States. doi:10.1103/PHYSREVLETT.98.145001.
@article{osti_20951212,
title = {Lateral Electron Transport in High-Intensity Laser-Irradiated Foils Diagnosed by Ion Emission},
author = {McKenna, P. and CCLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX14 0QX and Carroll, D. C. and Ledingham, K. W. D. and McCanny, T. and Robson, L. and Clarke, R. J. and Neely, D. and Robinson, A. P. L. and Evans, R. G. and Department of Physics, Imperial College, London, SW7 2AZ and Lindau, F. and Lundh, O. and Wahlstroem, C.-G. and Simpson, P. T. and Zepf, M.},
abstractNote = {An experimental investigation of lateral electron transport in thin metallic foil targets irradiated by ultraintense ({>=}10{sup 19} W/cm{sup 2}) laser pulses is reported. Two-dimensional spatially resolved ion emission measurements are used to quantify electric-field generation resulting from electron transport. The measurement of large electric fields ({approx}0.1 TV/m) millimeters from the laser focus reveals that lateral energy transport continues long after the laser pulse has decayed. Numerical simulations confirm a very strong enhancement of electron density and electric field at the edges of the target.},
doi = {10.1103/PHYSREVLETT.98.145001},
journal = {Physical Review Letters},
number = 14,
volume = 98,
place = {United States},
year = {Fri Apr 06 00:00:00 EDT 2007},
month = {Fri Apr 06 00:00:00 EDT 2007}
}
  • Hot electron transport along the target surface out of the laser-irradiated spot plays an important role in such applications as ion acceleration or fast ignition of fusion reactions. In this paper, the lateral electron transport in a thin foil, limited in transverse sizes, is studied by numerical particle-in-cell simulations for two linear polarizations (p and s) of femtosecond laser pulse incident on a foil at various angles. Two mechanisms of the transport are identified: the first one is due to hot electron recirculation across the foil and the second is electron guiding along the foil surface by quasistatic magnetic andmore » electric fields. It is demonstrated that the second mechanism takes place for larger incidence angles, although the recirculation is still important. The ions accelerated from a lateral foil edge, which is out of the laser focal spot, can have higher energies than the ions from the rear foil side.« less
  • Ion acceleration resulting from the interaction of ultra-high intensity (2 x 10{sup 20 }W/cm{sup 2}) and ultra-high contrast ({approx}10{sup 10}) laser pulses with 0.05-10 {mu}m thick Al foils at normal (0 deg.) and 35 deg. laser incidence is investigated. When decreasing the target thickness from 10 {mu}m down to 0.05 {mu}m, the accelerated ions become less divergent and the ion flux increases, particularly at normal (0 deg.) laser incidence on the target. A laser energy conversion into protons of {approx}6.5% is estimated at 35 deg. laser incidence. Experimental results are in reasonable agreement with theoretical estimates and can be amore » benchmark for further theoretical and computational work.« less
  • A complete analytical description of ion acceleration in the laser radiation-pressure regime is presented. The combined effects of hot electron and light-pressure phenomena are used to qualitatively and quantitatively describe most recent experimental results in this regime. An essential part of the developed model is exhibited in the calculation of nonlinear laser light reflection and transmission properties, as well as in the spectral characterization of the laser light after interaction. The validity of the analytical model is supported by recent experimental results and by particle-in-cell simulations.
  • Recent investigations of relativistic laser plasmas have shown that the energy transfer from the laser field to the kinetic ion energy and therefore the attainable maximum energy of the ions increases when ultrathin targets are irradiated by laser pulse without prepulse. In this paper, the influence of the target thickness and laser pulse contrast on the energy of the accelerated ions has been studied theoretically as well as experimentally. An optimum target was searched if a real laser pulse with a certain prepulse irradiates the target.
  • 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