Measurements of the 
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-Shell Opacity of a Solid-Density Magnesium Plasma Heated by an X-Ray Free-Electron Laser

Preston, Thomas R.; Vinko, S. M.; Ciricosta, O.; Hollebon, P.; Chung, H.‐K.; Dakovski, Georgi L.; Krzywiński, J.; Minitti, Michael P.; Burian, T.; Chalupský, J.; Hájková, V.; Juha, L.; Vozda, Vojtěch; Zastrau, U.; Lee, R. W.; Wark, J. S.

doi:10.1103/physrevlett.119.085001

Cited by 21 publications

(11 citation statements)

References 31 publications

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“…The intense x-ray pulse can drive x-ray photoionization of inner-shell electrons, provided the photon energy is higher than the shell’s ionization edge, and bound-bound transitions leading to excited atomic configurations, if the resonance energies are within the bandwidth of the x-ray pulse. Recombination into the core holes created by this interaction produces strong x-ray emission that has been spectrally resolved to identify ionization edges and deduce levels of CL 14 , 15 , observe non-linear processes 21 , measure x-ray opacities 16 and extract electron collisional ionization rates 23 , 24 .…”

Section: Approach and Validation In Almentioning

confidence: 99%

“…The most successful diagnostics to date have been x-ray inelastic scattering and x-ray emission spectroscopy. X-ray scattering experiments have recently investigated compressed CH plasmas on large-scale laser facilities Omega 12 and the NIF 13 , while spectroscopy has been deployed in campaigns investigating Mg, Al and Si using x-ray isochoric heating at the Linac Coherent Light Source (LCLS) free-electron laser 14 – 16 , and in fundamental plasma experiments on Al on the Orion laser at AWE 17 .…”

Section: Introductionmentioning

confidence: 99%

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Validating Continuum Lowering Models via Multi-Wavelength Measurements of Integrated X-ray Emission

Kasim

Wark

Vinko

2018

Sci Rep

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X-ray emission spectroscopy is a well-established technique used to study continuum lowering in dense plasmas. It relies on accurate atomic physics models to robustly reproduce high-resolution emission spectra, and depends on our ability to identify spectroscopic signatures such as emission lines or ionization edges of individual charge states within the plasma. Here we describe a method that forgoes these requirements, enabling the validation of different continuum lowering models based solely on the total intensity of plasma emission in systems driven by narrow-bandwidth x-ray pulses across a range of wavelengths. The method is tested on published Al spectroscopy data and applied to the new case of solid-density partially-ionized Fe plasmas, where extracting ionization edges directly is precluded by the significant overlap of emission from a wide range of charge states.

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Section: Approach and Validation In Almentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Validating Continuum Lowering Models via Multi-Wavelength Measurements of Integrated X-ray Emission

Kasim

Wark

Vinko

2018

Sci Rep

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“…Detailed studies of the X-ray spectra have led to an improved understanding of ionization potential depression (IPD) [3][4][5], as well as affording measurements of the femtosecond collisional ionization rates by means of the Auger-clock method [6,7]. Given the relatively long penetration depth of the X-rays compared with optical light, a study of the emission from slabs of plasma of varying thickness (from a few tens to a few hundred nm) has allowed direct measurements of K-shell opacity [8].…”

Section: Introductionmentioning

confidence: 99%

X-ray Spectroscopic Studies of a Solid-Density Germanium Plasma Created by a Free Electron Laser

et al. 2020

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The generation of solid-density plasmas in a controlled manner using an X-ray free electron laser (XFEL) has opened up the possibility of diagnosing the atomic properties of hot, strongly coupled systems in novel ways. Previous work has concentrated on K-shell emission spectroscopy of low Z (<= 14) elements. Here, we extend these studies to the mid-Z(=32) element Germanium, where the XFEL creates copious L-shell holes, and the plasma conditions are interrogated by recording of the associated L-shell X-ray emission spectra. Given the desirability of generating as uniform a plasma as possible, we present here a study of the effects of the FEL photon energy on the temperatures and electron densities created, and their uniformity in the FEL beam propagation direction. We show that good uniformity can be achieved by tuning the photon energy of the XFEL such that it does not overlap significantly with L-shell to M-shell bound-bound transitions, and lies below the L-edges of the ions formed during the heating process. Reasonable agreement between experiment and simulations is found for the emitted X-ray spectra, demonstrating that for these higher Z elements, the selection of appropriate XFEL parameters is important for achieving uniformity in the plasma conditions.

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“…This method has, to our knowledge, never been used experimentally. Preston et al [2], measured the K-shell emission of solid density magnesium by fitting the self-emission of planar targets to the solution of the radiative transfer equation.…”

Section: Introductionmentioning

confidence: 99%

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

Pérez-Callejo

Wark

Rose

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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We present solutions of the radiative transfer equation for cylinders, hollow hemi-ellipsoidal shells and tori for a uniform plasma of fixed geometry. The radiative transfer equation is explicitly solved for two directions of emission, parallel and perpendicular to the axis of symmetry. The ratio between the fluxes in these two directions is also calculated and its use in measuring the frequency resolved opacity of the plasma is discussed. We find that the optimal geometry to use this ratio as an opacity measurement is a planar geometry.

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Measurements of the K -Shell Opacity of a Solid-Density Magnesium Plasma Heated by an X-Ray Free-Electron Laser

Cited by 21 publications

References 31 publications

Validating Continuum Lowering Models via Multi-Wavelength Measurements of Integrated X-ray Emission

Validating Continuum Lowering Models via Multi-Wavelength Measurements of Integrated X-ray Emission

X-ray Spectroscopic Studies of a Solid-Density Germanium Plasma Created by a Free Electron Laser

Radiation transfer in cylindrical, toroidal and hemi-ellipsoidal plasmas

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