Conversion of laser light into x rays in thin foil targets

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

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Heterodyne Near Field Speckles: from laser light to X-rays

Advances in Physics X ◽

10.1080/23746149.2021.1891001 ◽

2021 ◽

Vol 6 (1) ◽

pp. 1891001

Author(s):

M. Siano ◽

B. Paroli ◽

M. A. C. Potenza

Keyword(s):

Laser Light ◽

Near Field ◽

X Rays

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Extremely High-Order Multiphoton Thomson Scattering: Synchrotron Hard X-Rays from Ultra-Intense Laser Light

2018 IEEE Photonics Conference (IPC) ◽

10.1109/ipcon.2018.8527124 ◽

2018 ◽

Author(s):

Donald Umstadter

Keyword(s):

Laser Light ◽

Thomson Scattering ◽

High Order ◽

Intense Laser ◽

X Rays

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M-L band x-rays (3–3.5 KeV) from palladium coated targets for isochoric radiative heating of thin foil samples

Journal of Physics B Atomic Molecular and Optical Physics ◽

10.1088/0953-4075/48/22/224002 ◽

2015 ◽

Vol 48 (22) ◽

pp. 224002 ◽

Cited By ~ 5

Author(s):

B Kettle ◽

T Dzelzainis ◽

S White ◽

L Li ◽

A Rigby ◽

...

Keyword(s):

Thin Foil ◽

Radiative Heating ◽

X Rays ◽

L Band

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A simple model for soft X-ray conversion efficiency from laser-irradiated gold disk targets

Laser and Particle Beams ◽

10.1017/s0263034600000902 ◽

1984 ◽

Vol 2 (3) ◽

pp. 303-307 ◽

Cited By ~ 6

Author(s):

P. H. Y. Lee ◽

H. G. Ahlstrom

Keyword(s):

Heat Conduction ◽

Simple Model ◽

Conversion Efficiency ◽

Laser Light ◽

Laser Intensity ◽

Laser Energy ◽

High Irradiance ◽

X Rays ◽

X Ray ◽

Laser Heated

Simple arguments are used to construct a model to explain the conversion efficiency of absorbed laser energy into soft X-rays from laser-irradiated targets. In this model, we postulate that the energy available for conversion is bounded at some low irradiance limit by heat conduction away from the laser heated spot, while at some high irradiance limit it is bounded by the energy lost in plasma blowoff. Consequently, at some appropriate laser intensity, where the sum energy of the conduction and blowoff losses is at a minimum, the X-ray conversion efficiency should reach a maximum. A specific example for gold disk targets irradiated by 0·53 μm laser light will be treated. Simple heuristic scalings of blowoff and conduction as functions of laser intensity are obtained.

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Investigation of light absorption, energy transfer, and plasma dynamic processes in laser-irradiated targets of low average density

Laser and Particle Beams ◽

10.1017/s0263034699173099 ◽

1999 ◽

Vol 17 (3) ◽

pp. 415-426 ◽

Cited By ~ 16

Author(s):

A.E. BUGROV ◽

I.N. BURDONSKII ◽

V.V. GAVRILOV ◽

A.Yu. GOL'TSOV ◽

S.Yu. GUS'KOV ◽

...

Keyword(s):

Energy Transfer ◽

Light Absorption ◽

Laser Light ◽

Plasma Layer ◽

Average Density ◽

Diagnostic Methods ◽

Radiative Energy ◽

X Rays ◽

Plasma Dynamic ◽

X Ray

The interaction of powerful laser and X-ray pulses with planar low average density (0.5–10 mg/cm3) porous agar-agar targets was experimentally studied. At a laser power density of ∼5 × 1013 W/cm2 (λ = 1.054 μm) the laser light absorption and following energy transfer processes, as well as dynamics of produced plasma were investigated in detail with a variety of optical and X-ray diagnostic methods. Volume absorption is shown to occur in experiments with laser-irradiated agar targets. An extended laser energy deposition region filled with hot (0.8–1 keV) plasma is formed inside a porous target. The laser light absorption efficiency is as high as ∼80%. The emission of 2ω0 and 3ω0/2 harmonics from laser-produced plasma is observed over the time of the laser pulse even with agar targets of 0.5 mg/cm3 average density. Characteristics of energy transfer in low-density porous media are measured in experiments on illumination of agar targets by laser pulses or X rays emitted by a thin Cu converter. The hydrodynamic mechanism is responsible for the energy transfer in laser-illuminated porous targets and the radiative energy transfer seems to be dominant in the case of X-ray irradiation. The experimental data are in reasonable agreement with predictions of a developed theoretical model describing the hot plasma layer formation and the two-stage homogenization process within the illuminated porous targets.

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The Soft X-Ray Laser Program at Livermore

International Astronomical Union Colloquium ◽

10.1017/s0252921100107754 ◽

1988 ◽

Vol 102 ◽

pp. 221

Author(s):

R.A. London ◽

N.M. Ceglio ◽

D.C. Eder ◽

A.U. Hazi ◽

C.J. Keane ◽

...

Keyword(s):

Laser Light ◽

Thin Foil ◽

Dielectronic Recombination ◽

Theoretical Modelling ◽

Collisional Excitation ◽

X Ray ◽

Dense Plasmas ◽

Spatial And Temporal Distributions ◽

Laser Facility ◽

Optical Laser

AbstractWe describe the experiments and supporting theoretical modelling to develop and characterize soft x-ray lasers. The x-ray lasers are created in dense plasmas produced by optical laser irradiation of solid targets with line focussed beams. We use mainly thin foil targets, which upon appropriate illumination, produce rather uniform plasmas. We consider laser schemes pumped by electron collisional excitation and dielectronic recombination in Ne-like and Ni-like ions, and schemes pumped by collisional and radiative recombination following rapid cooling for H-like and Li-like ions.Experimental measurements of the time and space resolved spectra taken both along the lasing axis and at other viewing angles, in addition to data on the angular pattern of x-ray laser radiation and on the absorption and scattering of the optical laser light are presented. These data allow us the determine the characteristics of the plasmas which have been created, as well as the properties of the x-ray lasers, such as the gain coefficients for the inverted transitions, and their spatial and temporal distributions. The modelling includes calculations of the absorption of the optical laser light, the hearing and hydrodynamics of the targets and the evolution of the atomic level populations within the plasma. Transfer of the emitted radiation is calculated, including resonance line trapping, amplification for inverted transitions, and refraction of the x-ray laser beam due to electron density gradients. Results are used to optimize x-ray laser designs before the experiments and to interpret the measured spectra.The latest experimental results from the NOVA laser facility on the performance of several laser schemes and on the use of multilayer mirrors to produce x-ray laser cavities are reported. These results arc compared to the models to test and improve our understanding of the complex physics involved in making x-ray lasers. Based on current experiments, we show how the modelling can be use to design shorter wavelength and more efficient schemes for use in applications such as x-ray holography.

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