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

1984 ◽  
Vol 2 (3) ◽  
pp. 303-307 ◽  
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.

scholarly journals Conversion of laser light into soft X rays with 3-ns and 30-ps laser pulses

1991 ◽  
Vol 9 (2) ◽  
pp. 551-562 ◽  
Author(s):  
K. Eidmann ◽  
W. Schwanda
Keyword(s):  
Laser Light ◽  
Laser Energy ◽  
Short Pulse ◽  
Laser Pulses ◽  
X Rays ◽  
Incident Laser ◽  
X Ray ◽  
Transmission Grating ◽  
Incident Laser Energy ◽  
Temporal And Spatial

The X-ray emission from planar targets made of aluminum, copper, or gold irradiated by a frequency-doubled Nd laser (530-nm wavelength and 1012–1014-W/cm2 laser intensity) was measured at two pulse durations: 3 ns and 30 ps. We absolutely measured the X-ray emission with spectral, temporal, and spatial resolution in the wavelength range 3 Å < λ < 250 Å by using filtered bolometers, a transmission grating spectrometer, X-ray diodes, and an X-ray streak camera as diagnostics. In addition, the absorption of laser light was measured. For the short, 30-ps laser pulse the conversion of incident laser energy into X rays was considerably less than that with the long, 3-ns pulse. This is caused by less absorption of laser light and, in addition, by less conversion of absorbed laser energy into X rays in the case of the short pulse. The results are compared with numerical simulations performed with the MULTI hydrocode.

scholarly journals Bright source of Kα and continuum X rays by heating Kr clusters using a femtosecond laser

2003 ◽  
Vol 21 (4) ◽  
pp. 535-540 ◽  
Author(s):  
R. ISSAC ◽  
J. WIRTHIG ◽  
E. BRUNETTI ◽  
G. VIEUX ◽  
B. ERSFELD ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Laser Intensity ◽  
Plasma Temperature ◽  
Hot Electrons ◽  
X Rays ◽  
X Ray ◽  
Laser Heated ◽  
Bright Source ◽  
The Continuum

X rays emitted from Kr clusters illuminated by a femtosecond laser have been observed over a wide spectral region from 3 keV to 15 keV. The measured spectra are characterized by a broad bremsstrahlung continuum and Kα, β lines at 12.66 keV and 14.1 keV. To the best of the authors' knowledge, this is the first observation of Kα, β emission from laser-heated Kr clusters. The bremsstrahlung continuum arising from collisions in the plasma implies a population of hot electrons consistent with a temperature of several kiloelectron volts. The absolute X-ray yield in the 3–15 keV region is found to be of the order of 107 photons per laser pulse. The plasma temperature, estimated from the continuum part of the spectrum as a function of laser intensity and X-ray yield as a function of laser pulse duration, are studied.

scholarly journals Laser contrast and other key parameters enhancing the laser conversion efficiency in ion acceleration regime

2018 ◽  
Vol 167 ◽  
pp. 02002 ◽  
Author(s):  
Lorenzo Torrisi
Keyword(s):  
Electric Field ◽  
Conversion Efficiency ◽  
Laser Light ◽  
Laser Intensity ◽  
Multilayered Structure ◽  
Maximum Energy ◽  
Ion Acceleration ◽  
Surface Geometry ◽  
Laser Parameters ◽  
Target Composition

Measurements of ion acceleration in plasma produced by fs lasers at intensity of the order of 1018 W/cm2 have been performed in different European laboratories. The forward emission in target-normal-sheath-acceleration (TNSA) regime indicated that the maximum energy is a function of the laser parameters, of the irradiation conditions and of the target properties.In particular the laser intensity and contrast play an important role to maximize the ion acceleration enhancing the conversion efficiency. Also the use of suitable prepulses, focal distances and polarized laser light has important roles. Finally the target composition, surface, geometry and multilayered structure, permit to enhance the electric field driving the forward ion acceleration.Experimental measurements will be reported and discussed.

STUDY OF TRANSVERSE EFFECTS IN THE PRODUCTION OF X-RAYS WITH A FREE-ELECTRON LASER BASED ON AN OPTICAL UNDULATOR

2007 ◽  
Vol 22 (23) ◽  
pp. 4270-4279
Author(s):  
A. BACCI ◽  
C. MAROLI ◽  
V. PETRILLO ◽  
L. SERAFNI ◽  
M. FERRARIO
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Free Electron Laser ◽  
Laser Energy ◽  
Laser Pulses ◽  
Collective Effects ◽  
Laser Source ◽  
X Rays ◽  
X Ray ◽  
Back Scattering

The interaction between high-brilliance electron beams and counter-propagating laser pulses produces X rays via Thomson back-scattering. If the laser source is long and intense enough, the electrons of the beam can bunch and a regime of collective effects can establish. In this case of dominating collective effects, the FEL instability can develop and the system behaves like a free-electron laser based on an optical undulator. Coherent X-rays can be irradiated, with a bandwidth very much thinner than that of the corresponding incoherent emission. The emittance of the electron beam and the distribution of the laser energy are the principal quantities that limit the growth of the X-ray signal. In this work we analyse with a 3-D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the X-ray spectra obtained. The scalings typical of the optical wiggler, characterized by very short gain lengths and overall time durations of the process make possible considerable emission also with emittance of the order of 1mm mrad.

scholarly journals Experimental and numerical study of ultra-short laser-produced collimated Cu Kα X-ray source

2017 ◽  
Vol 35 (3) ◽  
pp. 442-449 ◽  
Author(s):  
R. Rathore ◽  
V. Arora ◽  
H. Singhal ◽  
T. Mandal ◽  
J.A. Chakera ◽  
...  
Keyword(s):  
Laser Intensity ◽  
Numerical Study ◽  
Low Cost ◽  
Laser Pulses ◽  
Photon Flux ◽  
X Rays ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Short Laser Pulses

AbstractKα X-ray sources generated from the interaction of ultra-short laser pulses with solids are compact and low-cost source of ultra-short quasi-monochromatic X-rays compared with synchrotron radiation source. Development of collimated ultra-short Kα X-ray source by the interaction of 45 fs Ti:sapphire laser pulse with Cu wire target is presented in this paper. A study of the Kα source with laser parameters such as energy and pulse duration was carried out. The observed Kα X-ray photon flux was ~2.7 × 108 photons/shot at the laser intensity of ~2.8 × 1017 W cm−2. A model was developed to analyze the observed results. The Kα radiation was coupled to a polycapillary collimator to generate a collimated low divergence (0.8 mrad) X-ray beam. Such sources are useful for time-resolved X-ray diffraction and imaging studies.

scholarly journals Experiments with laser-irradiated cylindrical targets

1991 ◽  
Vol 9 (3) ◽  
pp. 725-747 ◽  
Author(s):  
C. Stöckl ◽  
G. D. Tsakiris
Keyword(s):  
Light Propagation ◽  
Energy Transport ◽  
Laser Light ◽  
Laser Energy ◽  
Axial Direction ◽  
Radiative Energy ◽  
Capillary Length ◽  
Inner Diameter ◽  
Laser Heated ◽  
Good Agreement

Results of novel experiments with laser-heated capillary targets are presented. In these experiments the interior of gold capillaries having a 200- or 700-μm inner diameter and a 2–12-mm length was axially irradiated by injection of the laser energy through one of the end openings. A frequency-doubled Nd:glass laser (λ = 0.53 μm) was employed, delivering 8-J energy in 3 ns. The experiments showed no significant backreflection of laser light. Depending on the capillary diameter and length, most of the laser energy is either transmitted or absorbed inside the capillary. The transmission of laser light was measured as a function of capillary length and found to be in good agreement with the predictions of a simple theoretical model. Two extreme cases could be identified. Capillaries with a 700-μm diameter show uninhibited laser light propagation due to multireflections off the inner wall. In contrast, at the entrance of capillaries with a 200-μm inner diameter a plasma plug forms that absorbs most of the laser energy. In both cases significant energy transport was observed to occur in the axial direction. A stable and strongly radiating plasma column is formed along the capillary axis by the collision of the radially imploding plasma. During the collision, part of the hydrodynamic energy of the plasma is converted into radiative energy. In a special case-a lower limit of ≊7% could be inferred for the conversion efficiency from laser light into X-ray radiation emitted from the rear opening of the capillary.

scholarly journals Dynamics of ultrafast heated radiative plasmas driven by petawatt laser light

2021 ◽  
Author(s):  
Kaoru Sugimoto ◽  
Natsumi Iwata ◽  
Atsushi Sunahara ◽  
Takayoshi Sano ◽  
Yasuhiko Sentoku
Keyword(s):  
Energy Density ◽  
Laser Light ◽  
Laser Intensity ◽  
High Energy ◽  
High Energy Density ◽  
Silver Foil ◽  
Cooling Process ◽  
Incident Laser ◽  
X Ray ◽  
Cooling Effects

Abstract A relativistic petawatt laser light can heat heavy metals over keV temperature isochorically and ionize them almost fully. Copious hard X-rays are emitted from the high-Z hot plasma which acts as X-ray sources, while they work as a cooling process of the plasma. The cooling process can affect on the creation of high energy density plasma via the interaction, however, the details are unknown. The X-ray spectrum depends on the plasma temperature, so that it is worthwhile to investigate the radiation cooling effects. We here study the isochoric heating of a solid silver foil irradiated by relativistic laser lights with a help of particle-in-cell simulations including Coulomb collisions, ionizations, and radiation processes. We have conducted a parameter survey varying laser intensity, 1018-20 W/cm2, to check the cooling effects while keeping the incident laser energy constant. The silver plasma heated mainly by the resistive heating dissipates its energy by keV X-ray emissions in a picosecond time scale. The radiation power from the silver foil is found to be comparable to the incident laser power when the laser intensity is less than 1019 W/cm2 under the constant energy situation. The evolution of the plasma energy density inside the target is then suppressed, due to which a highly compressed collisional shock is formed at the target surface and propagates into the plasma. The radiation spectra of the keV silver plasma are also demonstrated.

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

1999 ◽  
Vol 17 (3) ◽  
pp. 415-426 ◽  
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.

Simulations of femtosecond X-ray diffraction from unperturbed and rapidly heated single crystals

1999 ◽  
Vol 32 (4) ◽  
pp. 692-703 ◽  
Author(s):  
J. S. Wark ◽  
R. W. Lee
Keyword(s):  
Single Crystals ◽  
Time Scales ◽  
X Rays ◽  
Femtosecond Pulses ◽  
X Ray Diffraction ◽  
Similar Time ◽  
Short Pulses ◽  
X Ray ◽  
Laser Sources ◽  
Laser Heated

Simulations are presented of the dynamical diffraction of femtosecond pulses of X-rays from crystals whose structures are modified on similar time scales. Such simulations are of relevance to experiments in which short pulses of X-rays from synchrotron or laser sources are diffracted from rapidly laser-heated crystals.

scholarly journals Energy transport experiments at Institute of Laser Engineering, Osaka University

1989 ◽  
Vol 7 (3) ◽  
pp. 495-504 ◽  
Author(s):  
K. A. Tanaka ◽  
Y. Kato ◽  
S. Nakai ◽  
H. Shiraga ◽  
T. Yabe ◽  
...  
Keyword(s):  
Energy Transport ◽  
High Efficiency ◽  
Laser Energy ◽  
Rear Side ◽  
X Rays ◽  
Uv Laser ◽  
X Ray ◽  
Characteristic Emission ◽  
Irradiation Energy ◽  
The One

Emissions from the rear side of the targets were temporally resolved by irradiating an ultraviolet (UV) laser on Al and Au thin targets. A difference was clearly observed between the above two targets. Given the fact that absorbed laser energy is converted with a very high efficiency to soft x-rays in a high Z plasma, a characteristic emission peak only observed for Au targets was attributed to the effect of soft x-ray energy transport. The ablation pressures estimated from the emissions indicate that the pressure scaling for Au is close to the one by x-ray radiation rather than by a UV laser. With soft x-ray irradiation, energy transport in A1 foils was also studied. An ablation pressure was estimated by the shock speed.

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