Streaked x-ray spectrometer having a discrete selection of Bragg geometries for Omega

Millecchia, M.; Regan, S. P.; Bahr, R.; Romanofsky, M. H.; Sorce, C.

doi:10.1063/1.4729501

Cited by 13 publications

(5 citation statements)

References 5 publications

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“…28 In addition, a time-integrated x-ray microscope imager 33 observed the emission in the $3-to $7-keV photon-energy range. The XRFC employed a 4 Â 4 array of 10-lm-diam pinholes to produce 16 enlarged images of the target on a microchannelplate detector coupled to a charge-coupled-device camera.…”

Section: Diagnosticsmentioning

confidence: 99%

“…At the time of shock convergence, a short burst of x rays emitted from the target is detected with an x-ray framing camera (XRFC) 27 and a streaked x-ray spectrometer (SXS). 28 The hot electrons are characterized from the measured hard x-ray bremsstrahlung emission. Laser-backscatter diagnostics provide measurements of the absorbed laser power and the spectrally and temporally resolved optical emission generated by laser-plasma instabilities.…”

Section: Introductionmentioning

confidence: 99%

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Spherical strong-shock generation for shock-ignition inertial fusion

et al. 2015

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Recent experiments on the Laboratory for Laser Energetics' OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct laser illumination. The shocks are launched at pressures of several hundred Mbars and reach Gbar upon convergence. The results are relevant to the validation of the shock-ignition scheme and to the development of an OMEGA experimental platform to study material properties at Gbar pressures. The experiments investigate the strength of the ablation pressure and the hot-electron production at incident laser intensities of $2 to 6 Â 10 15 W/cm 2 and demonstrate ablation pressures exceeding 300 Mbar, which is crucial to developing a shockignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer the ablation and shock pressures. Laser-plasma instabilities produce hot-electrons with a moderate temperature (<100 keV). The instantaneous conversion efficiencies of laser power into hot-electron power reached up to $15% in the intensity spike. The large amount of hot electrons is correlated with an earlier x-ray flash and a strong increase in its magnitude. This suggests that hot electrons contribute to the augmentation of the shock strength. V C 2015 AIP Publishing LLC. [http://dx.

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Section: Diagnosticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spherical strong-shock generation for shock-ignition inertial fusion

et al. 2015

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“…The seed shock pressure is inferred from hydrodynamic simulations constrained by the measured temporal occurrence of the x-ray flash. The x-ray emission from the center of the target was measured temporally, spatially, and spectrally resolved using an x-ray framing camera (XRFC) [21] and a streaked x-ray spectrometer (SXS) [22]. The XRFC spatially and temporally resolved the x-ray emission, using a 4 × 4 pinhole array to produce 16 enlarged images of the target on a microchannel-plate detector, which was covered with four strips of gold film.…”

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confidence: 99%

Gigabar Spherical Shock Generation on the OMEGA Laser

et al. 2015

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This Letter presents the first experimental demonstration of the capability to launch shocks of several-hundred Mbar in spherical targets--a milestone for shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]. Using the temporal delay between the launching of the strong shock at the outer surface of the spherical target and the time when the shock converges at the center, the shock-launching pressure can be inferred using radiation-hydrodynamic simulations. Peak ablation pressures exceeding 300 Mbar are inferred at absorbed laser intensities of ∼3×10(15) W/cm2. The shock strength is shown to be significantly enhanced by the coupling of suprathermal electrons with a total converted energy of up to 8% of the incident laser energy. At the end of the laser pulse, the shock pressure is estimated to exceed ∼1 Gbar because of convergence effects.

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“…Bragg reflection crystal spectrometers recorded time-integrated and time-resolved x-ray spectra in the energy range of 7800–8600 eV. One spectrometer 58 was coupled to an x-ray streak camera to achieve 80-ps time-resolution; the other was coupled to x-ray–sensitive image plate.…”

Section: Methodsmentioning

confidence: 99%

“…The overall resolving power of the x-ray spectrometers is calibrated to be E/ ≈ 1100. The resolving power of the x-ray spectrometers is primarily limited by source size broadening and crystal rocking curve effects 58 .…”

Section: Methodsmentioning

confidence: 99%

Probing atomic physics at ultrahigh pressure using laser-driven implosions

Chin

et al. 2022

Nat Commun

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Spectroscopic measurements of dense plasmas at billions of atmospheres provide tests to our fundamental understanding of how matter behaves at extreme conditions. Developing reliable atomic physics models at these conditions, benchmarked by experimental data, is crucial to an improved understanding of radiation transport in both stars and inertial fusion targets. However, detailed spectroscopic measurements at these conditions are rare, and traditional collisional-radiative equilibrium models, based on isolated-atom calculations and ad hoc continuum lowering models, have proved questionable at and beyond solid density. Here we report time-integrated and time-resolved x-ray spectroscopy measurements at several billion atmospheres using laser-driven implosions of Cu-doped targets. We use the imploding shell and its hot core at stagnation to probe the spectral changes of Cu-doped witness layer. These measurements indicate the necessity and viability of modeling dense plasmas with self-consistent methods like density-functional theory, which impact the accuracy of radiation transport simulations used to describe stellar evolution and the design of inertial fusion targets.

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Streaked x-ray spectrometer having a discrete selection of Bragg geometries for Omega

Cited by 13 publications

References 5 publications

Spherical strong-shock generation for shock-ignition inertial fusion

Spherical strong-shock generation for shock-ignition inertial fusion

Gigabar Spherical Shock Generation on the OMEGA Laser

Probing atomic physics at ultrahigh pressure using laser-driven implosions

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