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Title: Production of Dense Plasmas with sub-10-fs Laser Pulses

Abstract

Close to solid state density plasmas with peak electron temperatures of about 190 eV have been generated with sub-10-fs laser pulses incident on solid targets. Extreme ultraviolet (XUV) spectroscopy is used to investigate the K shell emission from the plasma. In the spectra, a series limit for the H- and He-like resonance lines becomes evident which is explained by pressure ionization in the dense plasma. The spectra are consistent with computer simulations calculating the XUV emission and the expansion of the plasma.

Authors:
; ; ; ; ; ;  [1];  [2]
  1. Institute of Laser and Plasmaphysics, Heinrich-Heine-University Duesseldorf (Germany)
  2. Department of Physics, Clarendon Laboratory, University of Oxford, Oxford (United Kingdom)
Publication Date:
OSTI Identifier:
20777069
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevLett.96.085002; (c) 2006 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; COMPUTERIZED SIMULATION; ELECTRON TEMPERATURE; EV RANGE 100-1000; EXPANSION; EXTREME ULTRAVIOLET RADIATION; IONIZATION; K SHELL; LASER-PRODUCED PLASMA; LASERS; PLASMA DENSITY; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; PULSES; RESONANCE; SPECTROSCOPY

Citation Formats

Osterholz, J., Brandl, F., Fischer, T., Hemmers, D., Cerchez, M., Pretzler, G., Willi, O., and Rose, S.J. Production of Dense Plasmas with sub-10-fs Laser Pulses. United States: N. p., 2006. Web. doi:10.1103/PhysRevLett.96.085002.
Osterholz, J., Brandl, F., Fischer, T., Hemmers, D., Cerchez, M., Pretzler, G., Willi, O., & Rose, S.J. Production of Dense Plasmas with sub-10-fs Laser Pulses. United States. doi:10.1103/PhysRevLett.96.085002.
Osterholz, J., Brandl, F., Fischer, T., Hemmers, D., Cerchez, M., Pretzler, G., Willi, O., and Rose, S.J. Fri . "Production of Dense Plasmas with sub-10-fs Laser Pulses". United States. doi:10.1103/PhysRevLett.96.085002.
@article{osti_20777069,
title = {Production of Dense Plasmas with sub-10-fs Laser Pulses},
author = {Osterholz, J. and Brandl, F. and Fischer, T. and Hemmers, D. and Cerchez, M. and Pretzler, G. and Willi, O. and Rose, S.J.},
abstractNote = {Close to solid state density plasmas with peak electron temperatures of about 190 eV have been generated with sub-10-fs laser pulses incident on solid targets. Extreme ultraviolet (XUV) spectroscopy is used to investigate the K shell emission from the plasma. In the spectra, a series limit for the H- and He-like resonance lines becomes evident which is explained by pressure ionization in the dense plasma. The spectra are consistent with computer simulations calculating the XUV emission and the expansion of the plasma.},
doi = {10.1103/PhysRevLett.96.085002},
journal = {Physical Review Letters},
number = 8,
volume = 96,
place = {United States},
year = {Fri Mar 03 00:00:00 EST 2006},
month = {Fri Mar 03 00:00:00 EST 2006}
}
  • The extreme ultraviolet (XUV) emission from dense plasmas generated with sub-10-fs laser pulses with varying peak intensities up to 3x10{sup 16} W/cm{sup 2} is investigated for different target materials. K shell spectra are obtained from low Z targets (carbon and boron nitride). In the spectra, a series limit for the hydrogen- and helium-like resonance lines is observed, indicating that the plasma is at high density and that pressure ionization has removed the higher levels. In addition, L shell spectra from titanium targets were obtained. Basic features of the K and L shell spectra are reproduced with computer simulations. The calculationsmore » include hydrodynamic simulation of the plasma expansion and collisional radiative calculations of the XUV emission.« less
  • Intense laser pulse duration effects in the Coulomb explosion of the N{sub 2} molecule are studied using 10- and 40-fs laser pulses in the 10{sup 14}-10{sup 16} W cm{sup -2} intensity range. At 10 fs, no significant molecular stretching is observed during multi-ionization events up to the N{sup 2+}+N{sup 2+} fragmentation channel. Kinetic energy releases are larger and fragmentation yields are lower at 10 fs than at 40 fs due to the 1/R scaling of the molecular multi-ionization thresholds. These results open the way to Coulomb explosion imaging of neutral molecules using intense sub-10-fs laser pulses.
  • Double ionization channels of H{sub 2} are separated in the time domain using ultrashort 10-fs laser pulses in the 10{sup 13}-10{sup 15} W cm{sup -2} intensity range. Charge resonance enhanced ionization does not contribute anymore to double ionization because the H{sub 2}{sup +} ion does not have enough time to stretch up to the critical internuclear distance. Using a pump-probe excitation scheme, this process is shown to be very sensitive for the detection of pre- and post-pulses situated at a few tens of femtoseconds from the maximum pulse envelope.
  • Electrons have been accelerated from solid target surfaces by sub-10-fs laser pulses of 120 {mu}J energy which were focused to an intensity of 2x10{sup 16} W/cm{sup 2}. The electrons have a narrow angular distribution, and their observed energies exceed 150 keV. We show that these energies are not to be attributed to collective plasma effects but are mainly gained directly via repeated acceleration in the transient field pattern created by incident and reflected laser, alternating with phase-shift-generating scattering events in the solid.
  • An analysis made on the basis of the theory of the self-consistent field shows the possibility of production of ultrashort sub-10-fs soliton-like pulses in a solid-state laser with a coherent semiconductor switch in the absence of mode-locking caused by self-focusing. Mode-locking caused by self-focusing leads to the formation of an extremely short sech-shaped pulse. In this case, the restriction imposed on the minimum modulation degree in a passive semiconductor switch that provides self-starting USP generation is lifted. (nonlinear optical phenomena)