Analysis of time-resolved argon line spectra from OMEGA direct-drive implosions

Florido, R.; Nagayama, Taisuke; Mancini, Roberto; Tommasini, R.; Delettrez, J. A.; Regan, S. P.; Smalyuk, V. A.; Rodríguez, Rafael; Gil, Juan

doi:10.1063/1.2965779

Cited by 21 publications

(12 citation statements)

References 9 publications

(13 reference statements)

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“…On Omega, the MultiMonochromatic Imager has been successfully used to that effect. [18][19][20][21][22][23][24][25] An analogous MMI instrument has been built and qualified for experiments on the NIF by the DIME team. 26 However, in this work we describe the first step toward the diagnostics of mix on the NIF, in which we have opted to forgo the use of this new MMI in favor of collecting space integrated spectra by the Supersnout II diagnostic, 27 which records a time-integrated, 1-D spectral image of the implosion.…”

Section: Introductionmentioning

confidence: 99%

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

et al. 2014

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A series of experiments featuring laser-imploded plastic-shell targets filled with hydrogen or deuterium were performed on the National Ignition Facility. The shells (some deuterated) were doped in selected locations with Cu, Ga, and Ge, whose spectroscopic signals (indicative of local plasma conditions) were collected with a time-integrated, 1-D imaging, spectrally resolved, and absolute-intensity calibrated instrument. The experimental spectra compare well with radiation hydrodynamics simulations post-processed with a non-local thermal equilibrium atomic kinetics and spectroscopic-quality radiation-transport model. The obtained degree of agreement between the modeling and experimental data supports the application of spectroscopic techniques for the determination of plasma conditions, which can ultimately lead to the validation of theoretical models for thermonuclear burn in the presence of mix. Furthermore, the use of a lower-Z dopant element (e.g., Fe) is suggested for future experiments, since the ∼2 keV electron temperatures reached in mixed regions are not high enough to drive sufficient H-like Ge and Cu line emissions needed for spectroscopic plasma diagnostics.

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Section: Introductionmentioning

confidence: 99%

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

et al. 2014

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“…The total radiative power loss is then obtained as the sum of the three contributions. ABAKO and RAPCAL codes have been successfully tested with experimental results and numerical simulations for plasmas of both low and high Z-elements (for example: carbon, aluminium, argon, krypton, xenon or gold), either under LTE or NLTE conditions, in optically thin and thick (homogeneous and non-homogeneous) situations [22,23,25,45] and, recently, it has been proved their utility in K-shell spectroscopic diagnostics of aluminium [46] and argon [47,48] plasmas obtained in experiments carried out at LULI and OMEGA facilities, respectively. With respect to the simulations of xenon plasmas, in a previous work [23] was performed a numerical simulation of an experiment carried out at LULI [49] where an optically thick stationary xenon plasma was obtained.…”

Section: Theoretical Modelmentioning

confidence: 99%

Determination and Analysis of the Thermodynamic Regimes of Xenon Plasmas

Rodríguez¹,

Gil²,

Florido³

et al. 2011

Contrib. Plasma Phys.

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Xenon is a common element employed, for example, as impurity in magnetically confined plasmas or the medium in which radiative shocks propagate in laboratory astrophysics. In both situations, it is required the knowledge of plasma parameters such as the average ionization, the charge state distribution, the atomic level populations and the radiative properties. In most cases, the plasmas are under non-local thermodynamic equilibrium (NLTE) conditions and these quantities should be determined by means of the so-called collisionalradiative models. For a high Z element like xenon this is a complex task and entails a high computational cost since it is necessary to solve a very large set of rate equations. In this work are characterized the thermodynamic regimes of xenon plasmas as a function of the matter density and temperature. This fact will allow us to establish in which regions of density and temperature the assumption of local thermodynamic equilibrium (LTE) is accurate and also in which regions it can be retained to estimate some plasma parameters but not others. Moreover, it is also provided information about the average ionization in a wide range of plasma conditions which covers both LTE and NLTE regimes which is valuable information in order to optimize subsequent calculations. Finally, it is also performed an analysis of the differences of NLTE and LTE simulations on several relevant plasma parameters. With this purpose, a comparison is made between the results of the calculation using detailed NLTE modeling with simulations that use the same energy level structure, but atomic populations that are forced into LTE.

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“…25 and 26. In ICF experiments, diagnosis of core plasma temperature and density conditions is critical to assess the performance of implosion hydrodynamics. X-ray spectroscopy has proved to be a powerful technique to investigate different aspects of laser-fusion experiments 27 including target preheat due to fast electrons by means of Ka emission spectroscopy, 28,29 average electron temperature and density in implosion cores of directand indirect-drive implosions including Stark-broadened Kand L-shell line emissions, [30][31][32][33][34][35][36][37][38] spatial profiles of temperature and density from the analysis of x-ray spectra and narrowband images, [39][40][41] asymmetry measurements of plasma conditions spatial profiles from pinhole space-resolved spectra, 42 and the development of a polychromatic tomography method for the extraction of the 3D spatial structure of implosion core plasmas. 43 Here, we extend the application of x-ray spectroscopy to ICF experiments by presenting the first time-resolved measurements of core density and temperature in SI implosions.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved characterization and energy balance analysis of implosion core in shock-ignition experiments at OMEGA

et al. 2014

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Time-resolved temperature and density conditions in the core of shock-ignition implosions have been determined for the first time. The diagnostic method relies on the observation, with a streaked crystal spectrometer, of the signature of an Ar tracer added to the deuterium gas fill. The data analysis confirms the importance of the shell attenuation effect previously noted on time-integrated spectroscopic measurements of thick-wall targets [R. Florido et al., Phys. Rev. E 83, 066408 (2011)]. This effect must be taken into account in order to obtain reliable results. The extracted temperature and density time-histories are representative of the state of the core during the implosion deceleration and burning phases. As a consequence of the ignitor shock launched by the sharp intensity spike at the end of the laser pulse, observed average core electron temperature and mass density reach T $ 1100 eV and q $ 2 g/cm 3 ; then temperature drops to T $ 920 eV while density rises to q $ 3.4 g/cm 3 about the time of peak compression. Compared to 1D hydrodynamic simulations, the experiment shows similar maximum temperatures and smaller densities. Simulations do not reproduce all observations. Differences are noted in the heating dynamics driven by the ignitor shock and the optical depth time-history of the compressed shell. Time-histories of core conditions extracted from spectroscopy show that the implosion can be interpreted as a two-stage polytropic process. Furthermore, an energy balance analysis of implosion core suggests an increase in total energy greater than what 1D hydrodynamic simulations predict. This new methodology can be implemented in other ICF experiments to look into implosion dynamics and help to understand the underlying physics. V C 2014 AIP Publishing LLC. [http://dx.

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Analysis of time-resolved argon line spectra from OMEGA direct-drive implosions

Cited by 21 publications

References 9 publications

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

Determination and Analysis of the Thermodynamic Regimes of Xenon Plasmas

Time-resolved characterization and energy balance analysis of implosion core in shock-ignition experiments at OMEGA

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