A Particle X-ray Temporal Diagnostic (PXTD) for studies of kinetic, multi-ion effects, and ion-electron equilibration rates in Inertial Confinement Fusion plasmas at OMEGA (invited)

Sio, H.; Frenje, J. A.; Katz, J.; Stoeckl, C.; Weiner, D.; Bedzyk, M.; Glebov, V. Yu.; Sorce, C.; Johnson, M. Gatu; Rinderknecht, H. G.; Zylstra, A. B.; Sangster, T. C.; Regan, S. P.; Kwan, Thomas J. T.; Lê, A.; Simakov, Andrei N.; Taitano, William; Chacòn, Luis; Keenan, Brett; Shah, Rahul; Sutcliffe, G. D.; Petrasso, R. D.

doi:10.1063/1.4961552

Cited by 23 publications

(15 citation statements)

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“…28 The laser absorption (measured using a Full Aperture Back Scatter 29 system) and fuelshell trajectory (measured using X-ray framing cameras 30 ) are used to constrain postshot simulations. The primary observables-DD, DT, and D 3 He reaction histories-are simultaneously measured using the Particle X-ray Temporal Diagnostic (PXTD) 24 with high relative timing precision ($10 ps). On some shots, the Neutron Temporal Diagnostic 31 provided independent measurements of the DD and/or DT reaction histories.…”

Section: Omega Experimentsmentioning

confidence: 99%

“…With few exceptions, 10,23 the majority of existing experimental work investigating the role of kinetic and multi-ion physics in ICF implosions made use of time-integrated nuclear observables (reaction yields and ion temperatures). The experimental interaction signatures between the D, T, and 3 He ions are the DD, DT, and D 3 He reactions and measurements of the DD, DT, and D 3 He reaction histories using the Particle X-ray Temporal Diagnostic (PXTD) 24 enable time-resolved studies of these multi-ion effects. In this work, time-resolved DD, DT, and D 3 He reaction rates are used to probe the underlying changes in the plasma's temperature and density profiles and are compared with average-ion DUED 4 and kinetic-ion FPION 19 simulations.…”

Section: Introductionmentioning

confidence: 99%

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Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories

et al. 2019

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Simultaneously measured DD, DT, and D 3 He reaction histories are used to probe the impacts of multi-ion physics during the shock phase of inertial confinement fusion implosions. In these relatively hydrodynamiclike (burn-averaged Knudsen number hN K i $0.3) shock-driven implosions, average-ion hydrodynamic DUED simulations are able to reasonably match burnwidths, nuclear yields, and ion temperatures. However, kineticion FPION simulations are able to better simulate the timing differences and time-resolved reaction rate ratios between DD, DT, and D 3 He reactions. FPION simulations suggest that the D 3 He/DT reaction rate ratio is most directly impacted by ion species separation between the 3 He and T ions, whereas the D 3 He/DD reaction rate ratio is affected by both ion species separation and ion temperature decoupling effects.

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Section: Omega Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories

et al. 2019

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“…II, we provide the details of our OMEGA direct-drive ICF experiments. Section III reports the results from the analysis of multi-monochromatic x-ray imager (MMI) 39 data and particle x-ray temporal diagnostic (PXTD) 40 measurements. Section IV summarizes this paper.…”

Section: Introductionmentioning

confidence: 99%

Progress on observations of interspecies ion separation in inertial-confinement-fusion implosions via imaging x-ray spectroscopy

et al. 2019

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We report on the analyses of x-ray-imaging spectroscopy data from experiments to study interspecies ion separation in direct-drive inertial-confinement-fusion experiments on the Omega laser facility. This is a continuation of recent, related research [S. C. Hsu et al., Euro Phys. Lett. 115, 65001 (2016); T. R. Joshi et al., Phys. Plasmas 24, 056305 (2017)]. The targets were argon (Ar)-doped, deuterium (D2)-filled spherical plastic shells of varying D2-Ar relative and total gas pressures. We used a time- and space-integrated spectrometer, streaked crystal spectrometer, and up to three time-gated multi-monochromatic x-ray imagers (MMIs) fielded along different lines of sight to record x-ray spectral features obtained from the implosions. The MMI data were recorded between first-shock convergence and slightly before the neutron bang time. We confirm the presence of interspecies ion separation as reported in our recent work. Extensions to the previous work include (a) the inclusion of shell mix in the data analysis, which slightly changes the amount of inferred species separation, (b) observation of species separation closer to the neutron bang time, and (c) fielding of the particle x-ray temporal diagnostic (PXTD) [H. Sio et al., Rev. Sci. Instrum. 87, 11D701 (2016)] to infer the relative timing between the neutron bang time and peak x-ray emission. Experimentally inferred species separation is compared with radiation-hydrodynamic simulations that include a multi-ion-species transport model.

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“…In particular, the newly developed spectrometer at the National Ignition Facility (NIF) will infer the electron temperature from the hard X‐ray spectral continuum of 20 keV ≲ ℏ ω ≲ 30 keV, which is established through the free‐free Bremsstrahlung by electrons scattering off the fully ionized D and T ions . At the OMEGA laser facility, an electron temperature diagnostic is also being designed based on the time‐resolving streak‐camera approach, which will look at multiple energy bands in the range of 10 keV ≲ ℏ ω ≲ 30 keV in cryogenic and warm ICF implosions.…”

Section: Introductionmentioning

confidence: 99%

Inference of the electron temperature in inertial confinement fusion implosions from the hard X‐ray spectral continuum

Kagan

Landen

Svyatsky

et al. 2018

Contributions to Plasma Physics

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Using the free-free continuum self-emission spectrum at photon energies above 15 keV is one of the most promising concepts for assessing the electron temperature in inertial confinement fusion (ICF) experiments. However, these photons are due to suprathermal electrons whose mean free path is much larger than the thermal one, making their distribution deviate from Maxwellian in a finite-size hotspot. The first study of the free-free X-ray emission from an ICF implosion is conducted, accounting for the kinetic modifications to the electron distribution. These modifications are found to result in qualitatively new features in the hard X-ray spectral continuum. Inference of the electron temperature as if the emitting electrons are Maxwellian is shown to give a lower value than the actual one. KEYWORDShigh-energy-density, inertial confinement, x-ray diagnostic INTRODUCTIONKnowledge of the temperature of the deuterium-tritium (DT) hotspot is crucial for the success of inertial confinement fusion (ICF) experiments. [1,2] Accurate and reliable temperature measurements constrain theoretical models of the implosions and help identify shortcomings of presently available simulation tools, such as radiation-hydrodynamics codes. [3,4] Under thermonuclear conditions the fuel is in the form of a plasma, and the ion and electron temperatures, T i and T e , should generally be distinguished. The ion temperature can be inferred from the spectra of the fusion reaction products. [5,6] Information about the electron temperature is, in principle, carried by the radiation from the hot imploded plasma as this radiation is facilitated by free electrons scattering over ions. As electrons are much faster, it is their distribution only that governs the emission spectrum, which should then provide the basis for the T e inference.In practice, such an inference is obscured by opacity effects. The photon emitted in the hotspot has to travel through the hot-spot itself as well, as through the remnants of the shell, before being registered by spectrometers surrounding the implosion. With a substantial probability of a reabsorption or scattering event, it is a challenge to retrieve the emitting electron distribution from the measured emission spectrum. The current consensus is therefore that the successful diagnostic should operate using the harder part of the spectrum, that is, photon energies ℏ ≳ 15 keV 15 keV, for which the imploded capsule is transparent. [7][8][9][10] In particular, the newly developed spectrometer at the National Ignition Facility (NIF) will infer the electron temperature from the hard X-ray spectral continuum of 20 keV ≲ ℏ ≲ 30 keV, which is established through the free-free Bremsstrahlung by electrons scattering off the fully ionized D and T ions. [11] At the OMEGA laser facility, an electron temperature diagnostic is also being designed based on the time-resolving streak-camera approach, [12] which will look at multiple energy bands in the range of 10 keV ≲ ℏ ≲ 30 keV in cryogenic and warm ICF implosions.

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A Particle X-ray Temporal Diagnostic (PXTD) for studies of kinetic, multi-ion effects, and ion-electron equilibration rates in Inertial Confinement Fusion plasmas at OMEGA (invited)

Cited by 23 publications

References 14 publications

Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories

Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories

Progress on observations of interspecies ion separation in inertial-confinement-fusion implosions via imaging x-ray spectroscopy

Inference of the electron temperature in inertial confinement fusion implosions from the hard X‐ray spectral continuum

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