Prediction and observation of tin and silver plasmas with index of refraction greater than one in the soft x-ray range

Includes bibliographical references (pages 016404-6-016404-7).We present the calculated prediction and the experimental confirmation that doubly ionized Ag and Sn plasmas can have an index of refraction greater than one for soft x-ray wavelengths. Interferometry experiments conducted using a capillary discharge soft x-ray laser operating at a wavelength of 46.9 nm (26.44 eV) confirm that in few times ionized laser-created plasmas of these elements the anomalous dispersion from bound electrons can dominate the free electron contribution, making the index of refraction greater than one. The results confirm that bound electrons can strongly influence the index of refraction of numerous plasmas over abroad range of soft x-ray wavelengths confirming recent observations. The understanding of index of refraction at short wavelengths will become even more essential during the next decade as x-ray free electron lasers will become available to probe a wider variety of plasmas at higher densities and shorter wavelengths

Prediction and observation of tin and silver plasmas with index of refraction greater than one in the soft x-ray range

Includes bibliographical references (pages 016404-6-016404-7).We present the calculated prediction and the experimental confirmation that doubly ionized Ag and Sn plasmas can have an index of refraction greater than one for soft x-ray wavelengths. Interferometry experiments conducted using a capillary discharge soft x-ray laser operating at a wavelength of 46.9 nm (26.44 eV) confirm that in few times ionized laser-created plasmas of these elements the anomalous dispersion from bound electrons can dominate the free electron contribution, making the index of refraction greater than one. The results confirm that bound electrons can strongly influence the index of refraction of numerous plasmas over abroad range of soft x-ray wavelengths confirming recent observations. The understanding of index of refraction at short wavelengths will become even more essential during the next decade as x-ray free electron lasers will become available to probe a wider variety of plasmas at higher densities and shorter wavelengths

Dense plasma interferometry with a tabletop soft X-ray laser and an amplitude division interferometer based on diffraction gratings

Includes bibliographical references (page 486).We have demonstrated a novel Mach-Zehnder soft x-ray interferometer that uses diffraction gratings as beam splitters. The interferometer was used together with a 46.9nm tabletop soft x-ray laser, to map the evolution of the electron density distribution of a large-scale laser created plasma

Dense plasma diagnostics with an amplitude-division soft-x-ray laser interferometer based on diffraction gratings

Includes bibliographical references (page 358).We report the demonstration of an amplitude-division soft-x-ray interferometer that can be used to generate high-contrast interferograms at the wavelength of any of the saturated soft-x-ray lasers (5.6-46.9 nm) that are available at present. The interferometer, which utilizes grazing-incidence diffraction gratings as beam splitters in a modified Mach-Zehnder configuration, was used in combination with a tabletop 46.9-nm laser to probe a large-scale (~2.7-mm-long) laser-created plasma

Application of extremely compact capillary discharge soft x-ray lasers to dense plasma diagnostics

Includes bibliographical references.Table-top capillary discharge soft x-ray lasers combine the advantages of a small size and a high repetition rate with an extremely high brightness similar to that of their laboratory-size predecessors. When utilized to probe high density plasmas their short wavelength results in a higher critical density, reduced refraction, decreased free-electron absorption, and higher resolution as compared to optical probes. These characteristics allow the design of experiments capable of measuring the evolution of plasmas with density-scale length products that are outside the reach of optical lasers. This paper reviews the use of a 46.9 nm wavelength Ne-like Ar capillary discharge table-top laser in dense plasma diagnostics, and reports soft x-ray laser interferometry results of spot-focus Nd:YAG laser plasmas created at moderate irradiation intensity (~7×1012 W cm-2) with ; ~13 ns pulse width duration laser pulses. The measurements produced electron density maps with densities up to 0.9×1021 cm-3 that show the development of a concave electron density profile that differ significantly from those of a classical expansion. This two-dimensional behavior, that was recently also observed in line-focus plasmas, is analyzed here for the case of spot-focus plasmas with the assistance of hydrodynamic model simulations. The results demonstrate the use of a table-top soft x-ray laser interferometer as a new high resolution tool for the study of high density plasma phenomena and the validation of hydrodynamic codes.This work was supported by the U.S. Department of Energy Grant No. DE-FG03-02NA00062 and by the National Science Foundation. Part of this work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory through the Institute of Laser Science and Application, under Contract No. W-7405-Eng-48

Two-dimensional effects in laser-created plasmas measured with soft-x-ray laser interferometry

Includes bibliographical references (pages 056409-6).Soft-x-ray laser interferograms of laser-created plasmas generated at moderate irradiation intensities (1×1011-7×1012 W cm-2) with λ = 1.06 μm light pulses of ~13-ns-FWHM (full width at half maximum) duration and narrow focus (~30 μm) reveal the unexpected formation of an inverted density profile with a density minimum on axis and distinct plasma sidelobes. Model simulations show that this strong two dimensional hydrodynamic behavior is essentially a universal phenomena that is the result of plasma radiation induced mass ablation and cooling in the areas surrounding the focal spot

Observation of multiply ionized plasmas with dominant bound electron contribution to the index of refraction

Includes bibliographical references.We report anomalous fringe shifts observed in soft X-ray laser interferograms of laser-created Al plasmas. This clear experimental evidence shows that the contribution of bound electrons can dominate the index of refraction of laser-created plasmas at soft X-ray wavelengths, resulting in values greater than 1. The comparison of measured and simulated interferograms shows that this results from the dominant contribution of low-charge ions to the index of refraction. This usually neglected bound electron contribution can affect the propagation of soft X-ray radiation in plasmas and the interferometric diagnostics of plasmas for many elements.This work was sponsored by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Research Grant # DE-FG03-02NA00062. Part of this work was performed under the auspices of the US Department of Energy by the University of California, Lawrence Livermore National Laboratory through the Institute of Laser Science and Application, under Contract No. W-7405-Eng-48. The CSU researchers also gratefully acknowledge the partial support of the NSF ERC Center for Extreme Ultraviolet Science and Technology, award EEC-0310717

Observation of multiply ionized plasmas with dominant bound electron contribution to the index of refraction

Includes bibliographical references.We report anomalous fringe shifts observed in soft X-ray laser interferograms of laser-created Al plasmas. This clear experimental evidence shows that the contribution of bound electrons can dominate the index of refraction of laser-created plasmas at soft X-ray wavelengths, resulting in values greater than 1. The comparison of measured and simulated interferograms shows that this results from the dominant contribution of low-charge ions to the index of refraction. This usually neglected bound electron contribution can affect the propagation of soft X-ray radiation in plasmas and the interferometric diagnostics of plasmas for many elements.This work was sponsored by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Research Grant # DE-FG03-02NA00062. Part of this work was performed under the auspices of the US Department of Energy by the University of California, Lawrence Livermore National Laboratory through the Institute of Laser Science and Application, under Contract No. W-7405-Eng-48. The CSU researchers also gratefully acknowledge the partial support of the NSF ERC Center for Extreme Ultraviolet Science and Technology, award EEC-0310717

Extremely compact soft X-ray lasers based on capillary discharges

Includes bibliographical references (page 522).Extremely compact high repetition rate soft X-ray lasers based on capillary discharge excitation have demonstrated average powers of a few milliWatt at 46.9 nm, milli-Joule-level pulse energy, peak spectral brightness several orders of magnitude larger than third-generation synchrotron beam lines, and excellent spatial coherence. Examples of the use of a capillary discharge soft X-ray laser in dense plasma diagnostics and laser ablation of materials are summarized