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Title: Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters

Abstract

Intense, femtosecond irradiation of atomic and molecular clusters can initiate Coulomb explosions, generating particle energies sufficient to drive nuclear fusion. Last and Jortner have proposed, based on particle dynamics simulations, that heteronuclear clusters with a mixture of heavy and light ions will not explode by the simple, equilibrium Coulomb model but that dynamic effects can lead to a boosting of energy of the lighter ejected ions [Phys. Rev. Lett. 87, 033401 (2001)]. We present experimental confirmation of this theoretically predicted ion energy enhancement in methane clusters.

Authors:
; ; ; ; ; ; ; ; ;  [1]
  1. Texas Center for High Intensity Laser Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
20699539
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 95; Journal Issue: 19; Other Information: DOI: 10.1103/PhysRevLett.95.195003; (c) 2005 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; ACCELERATION; ATOMIC CLUSTERS; EQUILIBRIUM; EXPLOSIONS; HEAVY IONS; LASERS; LIGHT IONS; METHANE; MOLECULAR CLUSTERS; PLASMA PRODUCTION; SIMULATION

Citation Formats

Hohenberger, M., Symes, D.R., Madison, K.W., Sumeruk, A., Dyer, G., Edens, A., Grigsby, W., Hays, G., Teichmann, M., and Ditmire, T.. Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters. United States: N. p., 2005. Web. doi:10.1103/PhysRevLett.95.195003.
Hohenberger, M., Symes, D.R., Madison, K.W., Sumeruk, A., Dyer, G., Edens, A., Grigsby, W., Hays, G., Teichmann, M., & Ditmire, T.. Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters. United States. doi:10.1103/PhysRevLett.95.195003.
Hohenberger, M., Symes, D.R., Madison, K.W., Sumeruk, A., Dyer, G., Edens, A., Grigsby, W., Hays, G., Teichmann, M., and Ditmire, T.. Fri . "Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters". United States. doi:10.1103/PhysRevLett.95.195003.
@article{osti_20699539,
title = {Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters},
author = {Hohenberger, M. and Symes, D.R. and Madison, K.W. and Sumeruk, A. and Dyer, G. and Edens, A. and Grigsby, W. and Hays, G. and Teichmann, M. and Ditmire, T.},
abstractNote = {Intense, femtosecond irradiation of atomic and molecular clusters can initiate Coulomb explosions, generating particle energies sufficient to drive nuclear fusion. Last and Jortner have proposed, based on particle dynamics simulations, that heteronuclear clusters with a mixture of heavy and light ions will not explode by the simple, equilibrium Coulomb model but that dynamic effects can lead to a boosting of energy of the lighter ejected ions [Phys. Rev. Lett. 87, 033401 (2001)]. We present experimental confirmation of this theoretically predicted ion energy enhancement in methane clusters.},
doi = {10.1103/PhysRevLett.95.195003},
journal = {Physical Review Letters},
number = 19,
volume = 95,
place = {United States},
year = {Fri Nov 04 00:00:00 EST 2005},
month = {Fri Nov 04 00:00:00 EST 2005}
}
  • Intense, femtosecond irradiation of atomic and molecular clusters can initiate Coulomb explosions generating particle energies sufficient to drive nuclear fusion. It has been proposed that heteronuclear clusters with a mixture of heavy and light ions will not explode by the simple, equilibrium Coulomb model but that dynamic effects can lead to a boosting of energy of the lighter ejected ions. We present experimental confirmation of this theoretically predicted ion energy enhancement in methane and deuterated methane clusters. We then present data on fusion induced by explosions of dueterated methane clusters examining both fusion yield and neutron angular distribution.
  • Electron spectra from Ar{sub n} (n{<=}24 000) and doped Ar-CS{sub 2} clusters are studied experimentally at laser intensities of about 10{sup 15} W cm{sup -2}. More than an order of magnitude enhancement in the electron yield is observed in the case of doped Ar-CS{sub 2} clusters. The enhancement observed is argued to be because of the presence of species with low ionization potential, CS{sub 2}, in the cluster. Similar enhancement is also observed in K-shell emission when comparison is done between pure Ar{sub n} and mixed Ar-(CS{sub 2}) clusters under identical experimental conditions of laser irradiation. We also address themore » effect of doping CS{sub 2} clusters with dopant, Ar, which has higher ionization energy. We demonstrate a simple method for the characterization of doping level based on the Rayleigh scattering measurements.« less
  • Profiles of the Ly{sub {alpha}} line of O VIII ions in N{sub 2}O clusters irradiated by fs laser pulses (laser flux up to 4x10{sup 17} W/cm{sup 2}) were recorded. The features (peaks and dips) in the Ly{sub {alpha}} O VIII line profiles were observed. The experimental spectra were simulated theoretically assuming that strong oscillating electric fields are generated in the cluster plasma. We showed that allowing for oscillating electric fields of the amplitude E{sub 0}{approx}(0.5-1.0)x10{sup 9} V/cm and frequency {omega}{approx}(0.7-2.4)x10{sup 15} s{sup -1} leads to spectral features in the theoretical profiles of the Ly{sub {alpha}} O VIII line that aremore » similar to the features observed experimentally. Possible mechanisms responsible for the generation of strong oscillating electric fields in the cluster plasma are discussed.« less
  • The effect of an axial magnetic field on laser driven ion acceleration from a thin overdense plasma slab is investigated. The magnetic field modifies the refractive index of the plasma and the axial ponderomotive force. The latter compresses the electrons until the space charge field thus created offsets it. When the foil thickness is just bigger than the length at which this happens, the compressed electrons and a thin ion layer detach from the foil forming a double layer that gets accelerated by the laser radiation pressure force. The optimum thickness of laser foil, DELTA{sub s}, for maximum acceleration ismore » sensitive to the polarization of the laser pulse. For right circular polarization it increases, while for left circular polarization it decreases with the magnetic field. The ion energy gain is sensitive to a{sub 0}{sup 2}omega{sup 2}/DELTA{sub s}omega{sub p}{sup 2} (where a{sub 0} is the laser field strength, omega{sub p} is the plasma frequency, and omega is the laser frequency) and can be tuned by varying the magnetic field.« less