Simulation and analysis of time-gated monochromatic radiographs of cryogenic implosions on OMEGA

Epstein, R.; Stoeckl, C.; Goncharov, V. N.; McKenty, P. W.; Marshall, F. J.; Regan, S. P.; Betti, R.; Bittle, W.; Harding, D. R.; Hu, S. X.; Igumenshchev, I. V.; Jacobs‐Perkins, D.; Janezic, R.; Kelly, John; Kosc, T. Z.; Mileham, C.; Morse, Samuel Finley Breese; Radha, P. B.; Rice, Brian; Sangster, T. C.; Shoup, M. J.; Shmayda, W.T.; Sorce, C.; Ulreich, J.; Wittman, Mark D.

doi:10.1016/j.hedp.2017.04.005

Cited by 5 publications

(1 citation statement)

References 54 publications

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“…Improvements in our multi-physics codes now make this reanalysis a possibility. For example, Epstein et al [148] demonstrated that both short-pulse monoenergetic X-ray radiographs and self-emission x-ray images are well modeled by one-dimensional LILAC simulations. The legacy code used by the high-Z team before 2010 has been superseded by modern codes, and the high-Z experiments should be revisited with these tools.…”

Section: Discussionmentioning

confidence: 99%

Effect of Impurity Atoms on Thermonuclear Yield

Batha

2020

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The presence of impurity atoms in an inertial confinement fusion (ICF) implosion can greatly affect the burning of the thermonuclear fuel. This is a serious concern for attaining ignition as high atomic number atoms, such as carbon, can mix into the hot spot and reach the deuterium-tritium (DT) fuel, absorb energy from the implosion, and radiate away that energy. The temperature of the DT fuel drops and reduces the reactivity of the fuel resulting in lower thermonuclear yield. Fuel impurities can also be a useful diagnostic as when higher-Z atoms, such as Ar, Kr, and Xe, are purposefully mixed into the fuel. From the spectra emitted by these atoms, the temperature and density of the fuel can be deduced. The long history of using such tracer atoms by the national ICF program shows the great advances in experimental technique, diagnostic instruments, and atomic-physics modeling over the past 50 years. A particular set of experiments, the "High-Z" campaign, is reviewed in depth as this was the most systematic study of tracer element composition and quantity ever reported. Difficulties in interpreting the results of those experiments due to the limited code capabilities at that time are discussed. A main concern for the High-Z campaign was the then current state of non-Local Thermodynamic Equilibrium (nLTE) atomic physics models. The present state of nLTE modeling and its implementation in Los Alamos's multi-physics codes is discussed in this report. To further the understanding of the complex interaction of high-Z atoms in the gas, a survey of relevant existing experimental platforms at the National Ignition Facility (NIF) and the Omega Laser Facility are presented along with the current state of pertinent diagnostics at NIF and Omega. This review concludes with a discussion of the trade-off available between temperature and volume of the imploded ICF capsule with the goal of maximizing the total yield. 10 24 cm•3 3 x 10 23 cm•3

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Section: Discussionmentioning

confidence: 99%

Effect of Impurity Atoms on Thermonuclear Yield

Batha

2020

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Simulated refraction-enhanced X-ray radiography of laser-driven shocks

et al. 2019

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USARefraction-enhanced x-ray radiography (REXR) is used to infer shock-wave positions of more than one shock wave, launched by a multiple-picket pulse in a planar plastic foil.This includes locating shock waves before the shocks merge, during the early time and the main drive of the laser pulse that is not possible with the velocity interferometer system for any reflector. Simulations presented in this paper of REXR show that it is necessary to incorporate refraction and attenuation of x rays along with the appropriate opacity and refractive-index tables to interpret experimental images. Simulated REXR shows good agreement with an experiment done on the OMEGA laser facility to image a shock wave.REXR can be applied to design multiple-picket pulses with a better understanding of the shock locations. This will be beneficial to obtain the required adiabats for inertial confinement fusion implosions.

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Self-radiography of imploded shells on OMEGA based on additive-free multi-monochromatic continuum spectral analysis

et al. 2020

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Radiographs of pure-DT cryogenic imploding shells provide critical validation of progress toward ignition-scalable performance of inertial confinement fusion implosions [J. Nuckolls et al., Nature 239, 139 (1972)]. Cryogenic implosions on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] can be self-radiographed by their own core spectral emission near ≈2 keV. Utilizing the distinct spectral dependences of continuum emissivity and opacity, the projected optical-thickness distribution of imploded shells, i.e., the shell radiograph, can be distinguished from the structure of the core emission distribution in images. Importantly, this can be done without relying on spectral additives (shell dopants), as in previous applications of implosion self-radiography [V. A. Smalyuk et al., Phys. Rev. Lett. 87, 155002 (2001); L. A. Pickworth et al., ibid. 117, 035001 (2016)]. Demonstrations with simulated data show that this technique is remarkably well-suited to cryogenic implosions and can also be applied to self-radiography of imploded room-temperature CH shells at higher spectral energy (hv ≈ 3–5 keV) based on the very similar continuum spectrum of carbon. Experimental demonstration of additive-free self-radiography with warm CH shell implosions on OMEGA will provide an important proof of principle for future applications to cryogenic DT implosions.

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Simulation and analysis of time-gated monochromatic radiographs of cryogenic implosions on OMEGA

Cited by 5 publications

References 54 publications

Effect of Impurity Atoms on Thermonuclear Yield

Effect of Impurity Atoms on Thermonuclear Yield

Simulated refraction-enhanced X-ray radiography of laser-driven shocks

Self-radiography of imploded shells on OMEGA based on additive-free multi-monochromatic continuum spectral analysis

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