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Title: Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses

Abstract

We demonstrated enhancement of extreme ultraviolet (EUV) emission at 13.5 nm from a lithium plasma by use of dual laser pulses. A single laser pulse produced a lithium plasma condition for the EUV emission far beyond its optimum. Utilization of dual laser pulses, however, enhanced the EUV emission energy, and its maximum in-band EUV conversion efficiency (CE) in a measured solid angle was observed to be 2.4% at a pulse separation time between 20 and 50 ns. The EUV CE became 1.8 times as large as that produced by a single laser pulse, which was one of the highest values ever reported. Enhancement of the EUV CE was attributed to the decrease of the plasma temperature and density to their optimum values.

Authors:
; ; ;  [1]
  1. Department of Electrical and Electronic Engineering, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki 889-2192, Japan and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki 889-2192 (Japan)
Publication Date:
OSTI Identifier:
20779123
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 16; Other Information: DOI: 10.1063/1.2195904; (c) 2006 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; ELECTRON TEMPERATURE; EXTREME ULTRAVIOLET RADIATION; ION TEMPERATURE; LASER RADIATION; LASER-PRODUCED PLASMA; LITHIUM; PHOTON EMISSION; PLASMA DENSITY; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; PULSES

Citation Formats

Higashiguchi, Takeshi, Kawasaki, Keita, Sasaki, Wataru, and Kubodera, Shoichi. Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses. United States: N. p., 2006. Web. doi:10.1063/1.2195904.
Higashiguchi, Takeshi, Kawasaki, Keita, Sasaki, Wataru, & Kubodera, Shoichi. Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses. United States. doi:10.1063/1.2195904.
Higashiguchi, Takeshi, Kawasaki, Keita, Sasaki, Wataru, and Kubodera, Shoichi. Mon . "Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses". United States. doi:10.1063/1.2195904.
@article{osti_20779123,
title = {Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses},
author = {Higashiguchi, Takeshi and Kawasaki, Keita and Sasaki, Wataru and Kubodera, Shoichi},
abstractNote = {We demonstrated enhancement of extreme ultraviolet (EUV) emission at 13.5 nm from a lithium plasma by use of dual laser pulses. A single laser pulse produced a lithium plasma condition for the EUV emission far beyond its optimum. Utilization of dual laser pulses, however, enhanced the EUV emission energy, and its maximum in-band EUV conversion efficiency (CE) in a measured solid angle was observed to be 2.4% at a pulse separation time between 20 and 50 ns. The EUV CE became 1.8 times as large as that produced by a single laser pulse, which was one of the highest values ever reported. Enhancement of the EUV CE was attributed to the decrease of the plasma temperature and density to their optimum values.},
doi = {10.1063/1.2195904},
journal = {Applied Physics Letters},
number = 16,
volume = 88,
place = {United States},
year = {Mon Apr 17 00:00:00 EDT 2006},
month = {Mon Apr 17 00:00:00 EDT 2006}
}
  • Emission spectra from multiply charged potassium ions ranging from K{sup 3+} to K{sup 5+} have been obtained in the extreme ultraviolet (EUV) spectral region. A strong emission feature peaking around 38 nm, corresponding to a photon energy of 32.6 eV, is the dominant spectral feature at time-averaged electron temperatures in the range of 8−12 eV. The variation of this emission with laser intensity and the effects of pre-pulses on the relative conversion efficiency (CE) have been explored experimentally and indicate that an enhancement of about 30% in EUV CE is readily attainable.
  • We demonstrated enhancement of in-band conversion efficiency (CE) at 13.5 nm of the extreme ultraviolet (EUV) emission from a tin (Sn) cavity target irradiated by a CO{sub 2} laser pulse. Whereas a planar Sn target produced an in-band CE of around 2%, the use of cavity targets significantly enhanced the EUV emission energy and the EUV CE. An EUV CE of 4% was observed for a Sn cavity target with a depth of 200 {mu}m which is one of the highest values ever reported.
  • A double laser pulse heating scheme has been applied to generate plasmas with enhanced emission in the extreme ultraviolet (EUV). The plasmas were produced by focusing two laser beams (prepulse and main pulse) with a small spatial separation between the foci on a xenon gas jet target. Prepulses with ps-duration were applied to obtain high shockwave densities, following indications of earlier published results obtained using ns prepulses. EUV intensities around 13.5 nm and in the range 5-20 nm were recorded, and a maximum increase in intensity exceeding 2 was measured at an optimal delay of 140 ns between prepulse andmore » main pulse. The gain in intensity is explained by the interaction of the shockwave produced by the prepulse with the xenon in the beam waist of the main pulse. Extensive simulation was done using the radiative magnetohydrodynamic code Z{sup *}.« less
  • 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
  • Spherical solid tin targets were illuminated uniformly with twelve beams from the Gekko XII laser system to create spherical plasmas, and the extreme ultraviolet (EUV) emission spectra from the plasmas were measured. The highest conversion efficiency of 3% to 13.5 nm EUV light in 2% bandwidth was attained for an irradiance of around 5x10{sup 10} W/cm{sup 2}. The experimental results were reproduced fairly well using a theoretical model taking the power balance in the plasma into consideration.