X-Ray Thomson-Scattering Measurements of Density and Temperature in Shock-Compressed Beryllium

Lee, H. J.; Neumayer, P.; Castor, J.; Döppner, T.; Falcone, R. W.; Fortmann, C.; Hammel, B. A.; Kritcher, Andrea; Landen, O. L.; Lee, R. W.; Meyerhofer, D. D.; Munro, D.H.; Redmer, R.; Regan, S. P.; Weber, S. V.; Glenzer, S. H.

doi:10.1103/physrevlett.102.115001

Cited by 153 publications

(83 citation statements)

References 30 publications

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“…In warm dense matter, however, this spectrum blends with the bound-free scattering spectrum [18][19] that measures the momentum distribution of the bound electrons. Moreover, bound electrons with ionization energies larger than hω C /2π (states deep in the Fermi sphere) cannot be excited, and no energy can be transferred during the scattering process giving rise to an elastic scattering feature.…”

Section: Resolution Requirementsmentioning

confidence: 99%

Plasmon measurements with a seeded x-ray laser

et al. 2013

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Plasmon measurements hold great promise for providing highly accurate data on the physical properties of plasmas in the high-energy density physics regime. To this end we demonstrate in recent experiments at the Linac Coherent Light Source the first spectrallyresolved measurements of plasmons using a seeded 8-keV x-ray laser beam. Forward x-ray Thomson scattering spectra from isochorically heated solid aluminum show a well-resolved plasmon feature that is down-shifted in energy by 19 eV from the incident 8 keV elastic scattering feature. In this spectral range, the simultaneously measured backscatter spectrum shows no spectral features indicating observation of collective plasmon oscillations on a scattering length comparable to the screening length. This technique is a prerequisite for Thomson scattering measurements in compressed matter where the plasmon shift is a sensitive function of the free electron density and where the plasmon intensity provides information on temperature.

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Section: Resolution Requirementsmentioning

confidence: 99%

Plasmon measurements with a seeded x-ray laser

et al. 2013

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“…However, not all experiments [7][8][9][10][11][12][13] have observed this bcc phase, causing confusion and controversies. Be is important for both fundamental research [14][15][16][17] and practical applications. Being a strong and light-weight metal, it has been widely used in a broad range of technological applications in harsh environments and extreme PT conditions, e.g., up to T > 4,000 K and P > 200 GPa [18][19][20][21][22].…”

mentioning

confidence: 99%

Premelting hcp to bcc Transition in Beryllium

Sun

Zhang

et al. 2017

Phys. Rev. Lett.

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Beryllium (Be) is an important material with wide applications ranging from aerospace components to X-ray equipments. Yet a precise understanding of its phase diagram remains elusive. We have investigated the phase stability of Be using a recently developed hybrid free energy computation method that accounts for anharmonic effects by invoking phonon quasiparticles. We find that the hcp → bcc transition occurs near the melting curve at 0 < P < 11 GPa with a positive Clapeyron slope of 41 ± 4 K/GPa. The bcc phase exists in a narrow temperature range that shrinks with increasing pressure, explaining the difficulty in observing this phase experimentally. This work also demonstrates the validity of this theoretical framework based on phonon quasiparticle to study structural stability and phase transitions in strongly anharmonic materials.PACS numbers: 63.20. Ry, 81.30.Bx, 61.50.Ks,Elemental solids usually undergo a series of phase transitions from ambient conditions to extreme conditions [1][2][3]. Knowledge of their phase diagrams is a prerequisite for establishing their equations of state (EOS), a fundamental relation for determining thermodynamics properties and processes at high pressures and temperatures (PT). However, resolving phase boundaries is challenging for experiments given the uncertainties from several sources, especially at very high PT. Beryllium (Be) is a typical system whose phase diagram remains an open problem despite intense investigations. It assumes a hexagonal close-packed (hcp) structure at relatively low T [1]. Near the melting temperature T M (∼ 1, 550 K at 0 GPa), a competing phase with the body-centered cubic symmetry (bcc) seems to emerge [4][5][6]. However, not all experiments [7][8][9][10][11][12][13] have observed this bcc phase, causing confusion and controversies. Be is important for both fundamental research [14][15][16][17] and practical applications. Being a strong and light-weight metal, it has been widely used in a broad range of technological applications in harsh environments and extreme PT conditions, e.g., up to T > 4,000 K and P > 200 GPa [18][19][20][21][22].The bcc phase of Be was directly observed [4,5] only at T > 1, 500 K around ambient pressure before melting. Measurements of the temperature dependent resistance suggested that bcc Be is a high pressure phase and the hcp/bcc phase boundary between 0 < P < 6 GPa has a negative Clapeyron slope (−52 ± 8 K/GPa) [6]. However, recent experiments have challenged this conclusion [8,9,[11][12][13]. For example, it was reported that bcc Be was not observed for 8 < P < 205 GPa and 300 < T < 4, 000 K [13]. On the theory side, the study of Be's phase diagram using conventional methods encounters significant difficulties. The lattice dynamics of bcc Be is highly anharmonic, and the widely used quasi-harmonic approximation (QHA) and Debye model are not able to capture such effect [23][24][25][26][27][28][29]. For this reason, bcc Be and the associated hcp/bcc phase transition remain poorly understood for P < 11 GPa (density < 2.1g/...

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“…1.2). Non-collective Mn Heα spectra from a shocked Be experiment [14] were used to determine the electron density from the broadening of the Compton down-shifted spectrum and the electron temperature from the relative intensities of the Compton and Rayleigh peaks ( Fig. 1.2).…”

Section: X-ray Scatteringmentioning

confidence: 99%

“…1.2). Collective Ti Kα spectra from a shocked LiH experiment [14] were used to determine the electron density from the energy shift of the Plasmon feature and the ion temperature from the relative intensities of the Plasmon and Rayleigh features. A variety of diagnostic methods exist and which method is appropriate depends on the plasma conditions.…”

Section: X-ray Scatteringmentioning

confidence: 99%

X-ray thomson scattering measurements of warm dense matter.

Bailey¹,

Ao²,

Harding³

et al. 2012

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Warm dense matter exists at the boundary between traditional condensed matter and plasma physics and poses significant challenges to theoretical understanding. It is also critical for applications, including z-pinch and inertial fusion laboratory experiments and in astrophysical objects such as white dwarfs and giant planet interiors. The modern generation of high energy density facilities has made it possible to create warm dense conditions in the laboratory. Creating warm dense matter is challenging, but thorough understanding also requires accurate detailed diagnostics. This report describes research aimed at combining x-ray Thomson scattering, a powerful diagnostic for warm dense matter, with extreme environments created at the Z facility. Significant advances in in-house Sandia capability have been achieved, including x-ray scattering theory, instrumentation, and experiment design, execution, and interpretation. This work has set the stage for novel x-ray scattering investigations of warm dense matter at the Z facility in the near future.4

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X-Ray Thomson-Scattering Measurements of Density and Temperature in Shock-Compressed Beryllium

Cited by 153 publications

References 30 publications

Plasmon measurements with a seeded x-ray laser

Plasmon measurements with a seeded x-ray laser

Premelting hcp to bcc Transition in Beryllium

X-ray thomson scattering measurements of warm dense matter.

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