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X-ray scattering measurements of dissociation-induced metallization of dynamically compressed deuterium.

Davis P, Döppner T, Rygg JR, Fortmann C, Divol L, Pak A, Fletcher L, Becker A, Holst B, Sperling P, Redmer R, Desjarlais MP, Celliers P, Collins GW, Landen OL, Falcone RW, Glenzer SH - Nat Commun (2016)

Bottom Line: Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades.Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium.Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression.

View Article: PubMed Central - PubMed

Affiliation: University of California, Berkeley, California 94720, USA.

ABSTRACT
Hydrogen, the simplest element in the universe, has a surprisingly complex phase diagram. Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades. While sophisticated static experiments have probed hydrogen's structure at ever higher pressures, studies examining the higher-temperature regime using dynamic compression have mostly been limited to optical measurement techniques. Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium. Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression. The onset of ionization occurs close in pressure to where density functional theory-molecular dynamics (DFT-MD) simulations show molecular dissociation, suggesting hydrogen transitions from a molecular and insulating fluid to a conducting state without passing through an intermediate atomic phase.

No MeSH data available.


Related in: MedlinePlus

Measured forward scattering spectra with theoretical fits.Pressure and compression are inferred from VISAR measurements. X-ray forward scattering spectrum from 3.2 × shock-compressed D2 showing elastic scatter at 2005, eV and downshifted plasmon with theoretical fits corresponding to Te=0.15 eV and ne=1.3 (blue), 2.5 (red) and 4.0 (yellow) × 1022 cm−3. Below, a spectrum from 2.8 × compressed D2 showing no evidence of free electrons as a visible inelastic scattering feature.
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f4: Measured forward scattering spectra with theoretical fits.Pressure and compression are inferred from VISAR measurements. X-ray forward scattering spectrum from 3.2 × shock-compressed D2 showing elastic scatter at 2005, eV and downshifted plasmon with theoretical fits corresponding to Te=0.15 eV and ne=1.3 (blue), 2.5 (red) and 4.0 (yellow) × 1022 cm−3. Below, a spectrum from 2.8 × compressed D2 showing no evidence of free electrons as a visible inelastic scattering feature.

Mentions: Figure 4 shows collective scattering data measured with the forward spectrometer for two shock conditions. The upper spectrum is taken from the same shot as Fig. 3, with a compression of ρ/ρ0=3.2+0.2/−0.3 at the time of x-ray probing, while the lower spectrum used a lower laser intensity drive to reach ρ/ρ0=2.8+0.3/−0.4. At this lower drive condition, no inelastic feature is visible above the noise and spectral resolution of the detector, placing an upper bound on ionization state of Z≤0.04.


X-ray scattering measurements of dissociation-induced metallization of dynamically compressed deuterium.

Davis P, Döppner T, Rygg JR, Fortmann C, Divol L, Pak A, Fletcher L, Becker A, Holst B, Sperling P, Redmer R, Desjarlais MP, Celliers P, Collins GW, Landen OL, Falcone RW, Glenzer SH - Nat Commun (2016)

Measured forward scattering spectra with theoretical fits.Pressure and compression are inferred from VISAR measurements. X-ray forward scattering spectrum from 3.2 × shock-compressed D2 showing elastic scatter at 2005, eV and downshifted plasmon with theoretical fits corresponding to Te=0.15 eV and ne=1.3 (blue), 2.5 (red) and 4.0 (yellow) × 1022 cm−3. Below, a spectrum from 2.8 × compressed D2 showing no evidence of free electrons as a visible inelastic scattering feature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835540&req=5

f4: Measured forward scattering spectra with theoretical fits.Pressure and compression are inferred from VISAR measurements. X-ray forward scattering spectrum from 3.2 × shock-compressed D2 showing elastic scatter at 2005, eV and downshifted plasmon with theoretical fits corresponding to Te=0.15 eV and ne=1.3 (blue), 2.5 (red) and 4.0 (yellow) × 1022 cm−3. Below, a spectrum from 2.8 × compressed D2 showing no evidence of free electrons as a visible inelastic scattering feature.
Mentions: Figure 4 shows collective scattering data measured with the forward spectrometer for two shock conditions. The upper spectrum is taken from the same shot as Fig. 3, with a compression of ρ/ρ0=3.2+0.2/−0.3 at the time of x-ray probing, while the lower spectrum used a lower laser intensity drive to reach ρ/ρ0=2.8+0.3/−0.4. At this lower drive condition, no inelastic feature is visible above the noise and spectral resolution of the detector, placing an upper bound on ionization state of Z≤0.04.

Bottom Line: Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades.Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium.Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression.

View Article: PubMed Central - PubMed

Affiliation: University of California, Berkeley, California 94720, USA.

ABSTRACT
Hydrogen, the simplest element in the universe, has a surprisingly complex phase diagram. Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades. While sophisticated static experiments have probed hydrogen's structure at ever higher pressures, studies examining the higher-temperature regime using dynamic compression have mostly been limited to optical measurement techniques. Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium. Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression. The onset of ionization occurs close in pressure to where density functional theory-molecular dynamics (DFT-MD) simulations show molecular dissociation, suggesting hydrogen transitions from a molecular and insulating fluid to a conducting state without passing through an intermediate atomic phase.

No MeSH data available.


Related in: MedlinePlus