scholarly journals X-ray and ion emission studies from subnanosecond laser-irradiated SiO2 aerogel foam targets

2017 ◽  
Vol 35 (3) ◽  
pp. 505-512 ◽  
Author(s):  
C. Kaur ◽  
S. Chaurasia ◽  
A.A. Pisal ◽  
A.K. Rossall ◽  
D.S. Munda ◽  
...  
Keyword(s):  
Laser Energy ◽  
Laser System ◽  
Line Emission ◽  
Plasma Temperature ◽  
X Rays ◽  
Plasma Parameters ◽  
X Ray ◽  
Spectral Ranges ◽  
Ion Emission

AbstractIn this experiment, a comparative study of ion and X-ray emission from both a SiO2 aerogel foam and a quartz target is performed. The experiment is performed using Nd:glass laser system operated at laser energy up to 15 J with a pulse duration of 500 ps with focusable intensity of 1013–1014 W/cm2 on target. X-ray fluxes in different spectral ranges (soft and hard) are measured by using X-ray diodes covered with Al filters of thickness 5 µm (0.9–1.56 keV) and 20 µm (3.4–16 keV). A 2.5 times enhancement in soft X-ray flux (0.9–1.56 keV) and a decrease of 1.8 times in hard X rays (3.4–16 keV) for 50 mg/cc SiO2 aerogel foam is observed compared with the solid quartz. A decrease in the flux of the K-shell line emission spectrum of soft X rays is noticed in the case of the foam targets. The high-resolution K-shell spectra (He-like) of Si ions in both the cases are analyzed for the determination of plasma parameters by comparing with FLYCHK simulations. The estimated plasma temperature and density are Tc = 180 eV, ne = 7 × 1020 cm−3 and Tc = 190 eV, ne = 4 × 1020 cm−3 for quartz and SiO2 aerogel foam, respectively. To measure the evolution of the plasma moving away from the targets, four identical ion collectors are placed at different angles (22.5, 30, 45, and 67.5°) from target normal. The angular distribution of the thermal ions are scaled as cosnθ with respect to target normal, where n = 3.8 and 4.8 for the foam and quartz, respectively. The experimental plasma volume measured from the ion collectors and shadowgraphy images are verified by a two-dimensional Eulerian radiative–hydrodynamic simulation (POLLUX code).

Spectral Analysis of X-Rays from Laser-Induced Plasmas†

1974 ◽  
Vol 18 ◽  
pp. 159-168 ◽  
Author(s):  
J. F. Cuderman ◽  
K. M. Glibert
Keyword(s):  
Spectral Analysis ◽  
Total Energy ◽  
Spectral Range ◽  
Laser Energy ◽  
Laser System ◽  
X Rays ◽  
Laser Interaction ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Beam Laser

AbstractLaser interaction experiments have been conducted on Sandia Laboratories' four-beam laser system. In these experiments, pulses of 1.06 μm light of up to 50 J each were focused in a tetrahedral geometry onto CD2 microspheres. A 22-channel x-ray spectrometer which utilises silicon diodes with appropriate K-edge prefilters was used for x-ray measurements. Typically, bremsstrahlung-recombination spectra were observed in the photon regime below about 5 keV. The electron temperatures for this part of the spectrum ranged from a few hundred eV to 1 keV with up to 15 percent of the total laser energy converted to x-rays. Less than one percent of the total energy emitted as x-rays appeared in the spectral range above 5 keV.

scholarly journals Characterization of X-ray radiation from solid Sn target irradiated by femtosecond laser pulses in the presence of air plasma sparks

2016 ◽  
Vol 34 (3) ◽  
pp. 533-538 ◽  
Author(s):  
A. Curcio ◽  
M. Anania ◽  
F.G. Bisesto ◽  
A. Faenov ◽  
M. Ferrario ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Near Infrared ◽  
Laser Energy ◽  
Laser System ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
X Rays ◽  
Air Plasma ◽  
X Ray ◽  
Near Infrared Spectra

AbstractThe emission of X-rays from solid tin targets irradiated by low-energy (few mJ) femtosecond laser pulses propagated through air plasma sparks is investigated. The aim is that to better understand the X-ray emission mechanism and to show the possibility to produce proper radiation for spectroscopic and imaging applications with a table-top laser system. The utilization of a controlled ultrashort prepulse is found necessary to optimize the conversion efficiency of laser energy into Lα radiation. The optimum contrast between the main pulse and the controlled prepulse is found about 102. A correlation between the laser contrast value and the laser near-infrared spectra at the exit of the plasma spark is observed.

Application of Multilayer Structures to the Determination of Optical Constants in the X-Ray, Soft X-Ray and Extreme Ultra Violet Spectral Ranges

1988 ◽  
Vol 143 ◽  
Author(s):  
Troy W. Barbee
Keyword(s):  
Cross Sections ◽  
Optical Constants ◽  
Extreme Ultraviolet ◽  
Ultra Violet ◽  
Multilayer Structures ◽  
X Rays ◽  
X Ray ◽  
Spectral Ranges ◽  
Scattering Cross Sections

AbstractThe dispersion of x-rays (XR), soft x-rays (SXR) and extreme ultraviolet (EUV) light by multilayer structures is dependent on the scattering and absorption cross-sections of the elements used to synthesize the multilayer. In this paper it will be shown that this dependence provides a means for the accurate experimental determination of the optical constants of the multilayer constituents. Two specific approaches will be presented and discussed. First, it will be shown that detailed analysis of the energy dependence of the reflectivity of a simple depth periodic multilayer allows the unfolding of the optical constants. Secondly a new optic structure, the multilayer diffraction grating, will be described and it will be demonstrated that such combined microstructure optics allow the scattering cross-sections of the multilayer constituents to be accurately determined over broad spectral ranges.

Problems in Thin-Film X-ray Quantification

1990 ◽  
Vol 48 (2) ◽  
pp. 458-459
Author(s):  
J N Chapman ◽  
W A P Nicholson
Keyword(s):  
Thin Film ◽  
Specimen Thickness ◽  
X Rays ◽  
Characteristic Peak ◽  
Local Composition ◽  
X Ray ◽  
Measured Ratio ◽  
Path Lengths ◽  
Composition Changes

Energy dispersive x-ray microanalysis (EDX) is widely used for the quantitative determination of local composition in thin film specimens. Extraction of quantitative data is usually accomplished by relating the ratio of the number of atoms of two species A and B in the volume excited by the electron beam (nA/nB) to the corresponding ratio of detected characteristic photons (NA/NB) through the use of a k-factor. This leads to an expression of the form nA/nB = kAB NA/NB where kAB is a measure of the relative efficiency with which x-rays are generated and detected from the two species.Errors in thin film x-ray quantification can arise from uncertainties in both NA/NB and kAB. In addition to the inevitable statistical errors, particularly severe problems arise in accurately determining the former if (i) mass loss occurs during spectrum acquisition so that the composition changes as irradiation proceeds, (ii) the characteristic peak from one of the minority components of interest is overlapped by the much larger peak from a majority component, (iii) the measured ratio varies significantly with specimen thickness as a result of electron channeling, or (iv) varying absorption corrections are required due to photons generated at different points having to traverse different path lengths through specimens of irregular and unknown topography on their way to the detector.

scholarly journals Silicon in the solar corona

1965 ◽  
Vol 23 ◽  
pp. 115-123
Author(s):  
K. G. Widing ◽  
J. R. Porter
Keyword(s):  
Solar Corona ◽  
Relative Intensity ◽  
Line Emission ◽  
X Ray ◽  
Resonance Transitions ◽  
Spectral Ranges

Resonance lines of coronal ions of silicon are prominent in the spectral ranges 40–62 Å and 254–356 Å.An unexpected feature of the soft X-ray spectrum is the weakness or absence of the resonance lines of iron in ionization stages XI through XV.A second feature is the prominence of lines of the type (3d → 2p) relative to the resonance transitions (3p → 2s) in Li-like and Beryllium-like spectra. It is suggested that the upper levels (3d) are excited by quadrupole collisions from the ground 2s or 2s2levels.The intensity of the soft X-ray lines relative to the resonance lines in the 300 Å region seems to be more consistent with temperatures well above one million degrees than with temperatures as low as 700000°K, but the data are not adequate for a precise comparison. The relative intensity of the line emission from the various stages of silicon ionization may be interpreted as indicating that the ionization of silicon peaks in stages IX and X.The abundances of C, Mg, S, and Al relative to silicon do not seem to be greatly different from the chromospheric abundances reported by Pottasch or with the photospheric abundances.

scholarly journals Electronic Excitations and Radiation Damage in Macromolecular Crystallography

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 273 ◽  
Author(s):  
José Brandão-Neto ◽  
Leonardo Bernasconi
Keyword(s):  
Chemical Information ◽  
X Rays ◽  
Electronic Excitations ◽  
Macromolecular Crystallography ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Successful Approach ◽  
Structural Research

Macromolecular crystallography at cryogenic temperatures has so far provided the majority of the experimental evidence that underpins the determination of the atomic structures of proteins and other biomolecular assemblies by means of single crystal X-ray diffraction experiments. One of the core limitations of the current methods is that crystal samples degrade as they are subject to X-rays, and two broad groups of effects are observed: global and specific damage. While the currently successful approach is to operate outside the range where global damage is observed, specific damage is not well understood and may lead to poor interpretation of the chemistry and biology of the system under study. In this work, we present a phenomenological model in which specific damage is understood as the result of a single process, the steady excitation of crystal electrons caused by X-ray absorption, which acts as a trigger for the bulk effects that manifest themselves in the form of global damage and obscure the interpretation of chemical information from XFEL and synchrotron structural research.

Determination of the plasma parameters in the PF-3 facility by the methods of X-ray spectroscopy

2011 ◽  
Vol 37 (11) ◽  
pp. 935-947 ◽  
Author(s):  
E. O. Baronova ◽  
V. P. Vinogradov ◽  
V. I. Krauz ◽  
V. V. Myalton ◽  
A. M. Stepanenko ◽  
...  
Keyword(s):  
Plasma Parameters ◽  
X Ray

scholarly journals SPECTROSCOPY PECULIARITIES OF ELECTRIC ARC DISCHARGE PLASMA WITH IRON VAPOURS

2021 ◽  
pp. 171-175
Author(s):  
A. Murmantsev ◽  
A. Veklich ◽  
V. Boretskij
Keyword(s):  
Discharge Plasma ◽  
Arc Discharge ◽  
Line Emission ◽  
Plasma Temperature ◽  
Optical Emission ◽  
Plasma Source ◽  
Electric Arc ◽  
Spectral Lines ◽  
Electric Arc Discharge

This work is devoted to spectroscopy peculiarities of electric arc discharge plasma with iron vapours. The solution of the main issue of optical emission spectroscopy, namely, selection of iron spectral lines, to study the parameters of non-uniform and non-steady-state plasma source, was considered within this paper. Specifically, the Boltzmann plots technique was used for detailed analysing of application possibility of Fe I spectral lines as well as for determination of plasma temperature. The spatial profiles of selected spectral line emission intensities were used to measure the radial distributions of plasma temperature of free-burning arc discharge between consumable electrodes at 3.5 A.

scholarly journals Electronic Excitations and Radiation Damage in Macromolecular Crystallography

2018 ◽  
Author(s):  
José Brandão-Neto ◽  
Leonardo Bernasconi
Keyword(s):  
Chemical Information ◽  
X Rays ◽  
Electronic Excitations ◽  
Macromolecular Crystallography ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Successful Approach ◽  
Structural Research

Macromolecular crystallography at cryogenic temperatures has so far provided the majority of the experimental evidence that underpins the determination of the atomic structures of proteins and other biomolecular assemblies by means of single crystal X-ray diffraction experiments. One of the core limitations of the current methods is that crystal samples degrade as they are subject to X-rays, and two broad groups of effects are observed: global and specific damage. While the currently successful approach is to operate outside the range where global damage is observed, specific damage is not well understood and may lead to poor interpretation of the chemistry and biology of the system under study. In this work, we present a phenomenological model in which specific damage is understood as the result of a single process, the steady excitation of crystal electrons caused by X-ray absorption, which acts as a trigger for the bulk effects that manifest themselves in the form of global damage and obscure the interpretation of chemical information from XFEL and synchrotron structural research.

scholarly journals On the ionization of light gases by X-rays. I.—Technique

1933 ◽  
Vol 141 (845) ◽  
pp. 669-686
Keyword(s):  
Absolute Intensity ◽  
X Rays ◽  
X Ray ◽  
Quantitative Correlation ◽  
Quantitative Measurements ◽  
Fluorescent Radiation ◽  
A New Technique ◽  
Heavy Gas ◽  
Reliable Correlation

The measurement of the intensity of an X-ray beam in absolute units is in theory most satisfactorily accomplished by a determination of its heating effect. The method, however, is attended by considerable experimental difficulties, so that its application is very limited, and in practice it is usual to replace it by a determination of the ionization produced when the beam is passed through a gas. To correlate the ionization with an absolute intensity requires a quantitative knowledge of the details of the interaction between the X-rays and the molecules concerned and of the ionization of the gas by the ejected electrons. It sometimes happens that the processes involved about which we know least are relatively unimportant, so that a fairly reliable correlation can be made; and much work has been done on the application of the ionization method to X-ray dosimetry. But in general a quantitative correlation between ionization and intensity is not possible. A further study of the ionization of gases by X-rays is therefore desirable; moreover it may be made to yield important information concerning the processes involved. The early development of the physics of X-rays contains many examples of this, and more recently an important contribution has been made by Stockmeyer. The events leading to the ionization of a heavy gas are exceedingly complicated, whereas in the light gases (hydrogen and helium) some of these events are absent or else occur to a negligible extent, so that the interpretation of experiments with the latter becomes simpler and more reliable. These gases are therefore specially worthy of study. Moreover, for them the application of quantum mechanics leads to the most definite results for comparison with experiment, and in particular permits of a direct test of some aspects of Dirac’s theory of recoil scattering. The ionization due to the gas itself is, however, very small, and may even be less than the secondary ionization due to electrons liberated from the chamber walls. The technique used in ionization measurements with heavy gases is therefore unsuitable. Hitherto the only attempt made to extend such measurements to light gases is an experiment carried out in 1915 on hydrogen by Shearer who, however, obtained very variable results and an ionization markedly smaller than that to be expected from recoil electrons alone. Moreover his experimental method is now open to criticism in view of our greater knowledge of X-rays, and in particular the fluorescent radiation used was of doubtful homogeneity. The present paper will describe a new technique suitable for quantitative measurements of the ionization produced by X-rays in light gases, and in another paper it will be applied to a re-investigation of hydrogen.

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