Absolute X-ray yields from laser-irradiated, Ge-doped aerogel targets

Fournier, K. B.; Tobin, M.; Poco, J.F.; Bradley, K. S.; Hansen, Stephanie B.; Coverdale, C. A.; Beutler, D.E.; Severson, M.; Smith, Eugene A.; Reeder, D. L.

doi:10.1051/jp4:2006133092

Cited by 4 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 8 shows the comparison of ΔE k between the model (equation (10)) and the simulation result. The deviation is about 15% and it includes four parts: (1) the neglected shock wave compression work of the solid target; (2) the neglected heat wave expansion work of the foam target; (3) the error of equation ( 7); (4) the error of equation (9). Part (1) and (2) result in a larger ΔE k than the simulation result.…”

Section: The Improvement Of Conversion Efficiencymentioning

confidence: 95%

“…As discussed below, the model indicates a density dependence of P h that is consistent with the simulation result. In low-density foams, the shock wave surface is close to the critical surface (v s ≈ v c ) [16], and therefore, P h ≈ 0 according to equation (9). To analyze the P h of a high-density target, equation ( 9) is rewritten as below.…”

Section: Heat Wave Expansion Workmentioning

confidence: 99%

“…Under-critical foam (also called underdense foam), an extremely low density material whose electron density is lower than the critical density determined by laser wavelength, produces a higher hard x-ray yield compared with the solid material [6]. It has been widely applied in multi-keV x-ray sources using mid-Z metallic materials such as titanium [7], iron [8], and germanium [9]. The mechanism that causes the hard x-ray enhancement has been clarified: the laser ionization wave (also called the bleaching wave) in under-critical foam induces supersonic heating, which could not efficiently drive the hydrodynamic motion and thus reduces the kinetic energy [10].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling the x-ray enhancement in foams for laser-driven soft x-ray sources

et al. 2022

View full text Add to dashboard Cite

This paper investigates the mechanism that causes the x-ray enhancement in high-Z foams for laser-driven soft x-ray sources. By simulation of one-dimensional radiation-hydrodynamics, it is found that the x-ray enhancement is mainly due to the effect that, in foam target, shock wave compression significantly reduces the energy loss of hydrodynamic motion (kinetic energy). In solid target this effect is negligible for its low compressibility. Expressions of kinetic energy reduction (∆Ek=Ek,solid-Ek,foam) are given to model the improvement of laser-to-x-ray conversion efficiency. The ∆Ek given by the model agrees with the simulation result with about 15% error for foam density 0.07~0.3g/cc and for laser intensity 0.4×1015~2.0×1015W/cm2. The model indicates that the x-ray enhancement is more efficient with lower foam density and higher laser intensity, which is also presented by the simulation results.

show abstract

Section: The Improvement Of Conversion Efficiencymentioning

confidence: 95%

Section: Heat Wave Expansion Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling the x-ray enhancement in foams for laser-driven soft x-ray sources

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Polycrystalline materials are interrogated with a collimated quasi-monochromatic X-ray source. We use helium-alpha emission from laser-produced plasma produced by a metallic foil or foam 14 target made of a mid-Z element. Simultaneously with the diffraction data we will monitor the target compression using VISAR to obtain not only information about the crystal's phase and strain history, but also the stress profiles.…”

Section: Experimental Feasibilitymentioning

confidence: 99%

X-ray diffraction studies of dynamically compressed diamond

Eggert

2010

View full text Add to dashboard Cite

X-ray Diffraction Studies of Dynamically Compressed Diamond Purpose:We propose a series of experiments to use X-ray diffraction (XRD) to study material properties using the NIF. XRD is the best way to determine the structure, lattice deformation, and texture of materials. Advances in synchrotron XRD facilities in the past two decades have revolutionized the study of materials at static high pressure in diamond anvil cells (DACs) up to about 3 Mbar. The National Ignition Facility (NIF) has the potential to do the same for dynamic materials studies at high-pressure. Members of our scientific team have pioneered XRD on many smaller laser facilities around the world. Our results suggest that diffraction on solids approaching 100 Mbar may be possible on the NIF, providing access to new regime for matter at extreme conditions. Scientific Case:An understanding of the fundamental physics of the response of matter to rapid compression -be it shock or quasi-isentropic -remains an important, elusive challenge in the fields of laser-matter interactions and high energy-density physics. The capabilities of the NIF greatly expand capabilities in this burgeoning field, as the high energy and long shaped-pulse capability of this unique platform will allow the precise temporally-controlled compression of matter to many tens of Mbars, heralding a new era of high-pressure materials science, with the potential to uncover hitherto unknown highpressure crystalline phases and material properties.The aim of this proposal is to reach an understanding, at the atomic level, of the pathways taken to, and the final forms of, these new states of matter. The diagnostic of choice is nanosecond X-ray diffraction. This proven technique, pioneered on more modest laser platforms (at consequently lower pressures) by the applicants, affords the potential for direct monitoring of lattice deformation before, during, and after polymorphic phase transitions. We are firmly of the view that dynamic ultra-highpressure materials science on NIF will be an extremely fruitful area of study. There are many materials that we wish to interrogate as the field matures, with varying, but equally compelling scientific rationales. This consortium proposes an initial concentration on polycrystalline diamond targets using an angle dispersive camera.There are two persuasive reasons for this approach. First, the beauty of materials with the diamond cubic structure is that we can obtain single-crystal samples which are, for most purposes, 'perfect' -i.e. dislocation free. There is a strong line of reasoning that indicates these materials are better suited for theoretical modeling, both in terms of ab-initio calculations, and large (multi-million to billion atom) classical molecular dynamics calculations. Second, low-Z, strong and/or highly anisotropic materials, such as diamond and beryllium remain as candidates for ablator materials for ICF targets. Depending upon the target and drive-pulse designs, material phase, strength, texture, and lattice response may play a role in...

show abstract

“…Given the laser energies and intensities available with the systems that have been used for shock compression and diffraction experiments, the highest photon energies used to date correspond to the helium resonance line of copper at 8.4 keV ͑although it has been shown that this could be extended to the resonance line of He-like Ge͒. 28 On the other hand, in the picosecond and subpicosecond regime, the huge intensities that can be produced Ͼ10 18 W cm −2 induce the excitation and breaking of plasma waves, resulting in short bursts of energetic electrons penetrating the underlying target, producing a short burst of K␣ emission in an analogous manner to a conventional x-ray tube. It has been shown that such techniques can readily produce K-shell radiation up to 22 keV.…”

Section: Relation To Experimentsmentioning

confidence: 99%

Molecular dynamics simulations of the Debye-Waller effect in shocked copper

et al. 2008

View full text Add to dashboard Cite

We present an analysis of the directionally dependent x-ray structure factors ͑and, hence, intensities͒ predicted by nonequilibrium molecular dynamics simulations of statically compressed and shocked single crystals of copper, and comment on the feasibility of using experimentally measured intensities to infer temperature information. We further consider the behavior of the diffracted intensity from isentropically compressed samples.

show abstract

Absolute X-ray yields from laser-irradiated, Ge-doped aerogel targets

Cited by 4 publications

References 0 publications

Modeling the x-ray enhancement in foams for laser-driven soft x-ray sources

Modeling the x-ray enhancement in foams for laser-driven soft x-ray sources

X-ray diffraction studies of dynamically compressed diamond

Molecular dynamics simulations of the Debye-Waller effect in shocked copper

Contact Info

Product

Resources

About