Broadband high-resolution elliptical crystal x-ray spectrometer for high energy density physics experiments

Anderson, S. G.; Heeter, R. F.; Booth, R.; Emig, J.; Fulkerson, S.; McCarville, T.; Norman, D.; Young, B. K.

doi:10.1063/1.2214688

Cited by 14 publications

(6 citation statements)

References 14 publications

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“…Together, these should result in improved background subtraction methods. A further step is to drastically reduce the diffuse scattering visible at the detector by switching to a concave elliptical crystal geometry with a crossover slit, similar in concept to the OZSPEC instrument [27,28] but without the gated detector. The crossover slit reduces by a factor of 5-10 the fraction of the crystal (and substrate) seen by any given detector pixel, which should reduce the scattered background proportionately.…”

Section: Diffuse Scattering and Fluorescencementioning

confidence: 99%

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Heeter

Perry

Johns

et al. 2018

Atoms

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Discrepancies exist between theoretical and experimental opacity data for iron, at temperatures 180-195 eV and electron densities near 3 × 10 22 /cm 3 , relevant to the solar radiative-convective boundary. Another discrepancy, between theory and helioseismic measurements of the boundary's location, would be ameliorated if the experimental opacity is correct. To address these issues, this paper details the first results from new experiments under development at the National Ignition Facility (NIF), using a different method to replicate the prior experimental conditions. In the NIF experiments, 64 laser beams indirectly heat a plastic-tamped rectangular iron-magnesium sample inside a gold cavity. Another 64 beams implode a spherical plastic shell to produce a continuum X-ray flash which backlights the hot sample. An X-ray spectrometer records the transmitted X-rays, the unattenuated X-rays passing around the sample, and the sample's self-emission. From these data, X-ray transmission spectra are inferred, showing Mg K-shell and Fe L-shell X-ray transitions from plasma at a temperature of~150 eV and electron density of~8 × 10 21 /cm 3 . These conditions are similar to prior Z measurements which agree better with theory. The NIF transmission data show statistical uncertainties of 2-10%, but various systematic uncertainties must be addressed before pursuing quantitative comparisons. The paths to reduction of the largest uncertainties are discussed. Once the uncertainty is reduced, future NIF experiments will probe higher temperatures (170-200 eV) to address the ongoing disagreement between theory and Z data.

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Section: Diffuse Scattering and Fluorescencementioning

confidence: 99%

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Heeter

Perry

Johns

et al. 2018

Atoms

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“…15,16 With this in mind, we set as a goal achieving an x-ray flash with a duration between 80 and 230 ps. There are two characteristic times associated with an MCP: the high-voltage pulse propagation time t MCP across the MCP and the duration ⌬t HV of this pulse.…”

Section: Emission Time Historymentioning

confidence: 99%

Dynamic Hohlraums as x-ray sources in high-energy density science

Hansen

Glendinning

Heeter

et al. 2008

Review of Scientific Instruments

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The first demonstration of laser driven dynamic Hohlraums (LDDH) as a spectrally smooth backlighter source for opacity and temperature measurements through absorption spectrometry of materials in local thermodynamic equilibrium at temperatures >150 eV has been made. This is a crucial temperature regime for future astrophysics and ignition fusion experiments at the nearly completed National Ignition Facility (NIF) [E. I. Moses and C. R. Wuest, Fusion Sci. Technol. 47, 314 (2005)] at the Lawrence Livermore National Laboratory. The new backlighter consists of a LDDH filled with either krypton or argon that implodes to create an x-ray flash. The properties of this x-ray flash have been measured in experiments at the Omega laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] at the Laboratory for Laser Energetics in Rochester, New York, satisfying all requirements imposed by future experiments: (1) the emission spectrum extends to at least 5.5 keV, well above the maximum x-ray energy ( approximately 3.5 keV) obtained from the previously "best" opacity backlighters (uranium M-shell emission backlighters); (2) the spectrum is smooth and featureless (intensity variation <6% rms), allowing absorption spectrometry through experimental samples; (3) the emission source size is sufficiently small (<50 microm) for projection backlighting through future samples; (4) the emission is bright enough (and twice as bright as imploding hydrogen-filled capsules) for gated spectrometer measurements; (5) the emission duration is optimized ( approximately 100 ps) for the current and future generations of spectrometers; and (6) by using only a small number of beams with limited energy and symmetry for the backlighter (10 out of 60 beams in the Omega experiments), the majority of laser beams are left available for heating sample materials to >150 eV.

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“…Compared to a conventional spherical surface, the point-to-point focusing provided by an elliptical surface not only reduces the impact of the source size on spectral resolution but also provides a broader range of Bragg angles and a wider energy range. Anderson et al developed a three-channel, ellipsoidal, opacityzipper spectrometer (OZSPEC) that covers the energy range of 0.24-5.80 keV; it achieved a spectral resolution E/ ∆E greater than 400, which is 2-3 times larger than that provided by a spherical surface [14]. Heeter et al developed a modified version of the OZSPEC-2 structure that further improved the spectral resolution E/ ∆E to more than 500 [15].…”

Section: Introductionmentioning

confidence: 99%

A Wide-Range High-Resolution X-ray Crystal Spectrometer for Laser–Plasma Diagnostics

Yi,

Du,

et al. 2023

Photonics

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Wide-range crystal spectrometers are important tools for performing X-ray spectroscopic measurements of medium- and high-Z tracer elements in research on laser-driven inertial confinement fusion (ICF) plasmas. In this paper, we propose a wide-range high-resolution crystal spectrometer based on a tandem array of crystals that have the same geometric parameters. We have developed a three-channel crystal spectrometer that covers the range of 8–18 keV by combining Ge<311>, Ge<331>, and Ge<531> crystals. Here, we report the design, optical simulations, and X-ray test experiments of this spectrometer. The calibration results indicate that the spectral resolution E/ΔE is greater than 2800 at 8.048 keV. By selecting appropriate Bragg angles, crystal materials, orientations, or other geometrical parameters, the wide-range crystal spectrometer developed in this paper can also be used to make measurements in other energy ranges.

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Broadband high-resolution elliptical crystal x-ray spectrometer for high energy density physics experiments

Cited by 14 publications

References 14 publications

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Dynamic Hohlraums as x-ray sources in high-energy density science

A Wide-Range High-Resolution X-ray Crystal Spectrometer for Laser–Plasma Diagnostics

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