Erratum: “DMX: An absolutely calibrated time resolved broadband soft x-ray spectrometer designed for MJ class laser produced plasmas” [Rev. Sci. Instrum. <b>72</b>, 1173 (2001)]

Bourgade, J. L.; Villette, B.; Bocher, J. L.; Boutin, Jean-Yves; Chiche, S.; Dague, N.; Gontier, D.; Jadaud, J. P.; Savale, B.; Wrobel, R.; Turner, R. E.

doi:10.1063/1.1372175

Cited by 17 publications

(15 citation statements)

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“…Moreover, the rapid expansion of the foil during the heating is limited by placing the foil between two thin samples of a low Z material (here carbon), playing the role of inertial confinement to prevent an uncontrolled hydrodynamic expansion resulting in a dramatically decrease of the density. We measure the radiative temperature of the X radiation in the cavity thanks to a 12 channels spectrometer which measures X-rays energy (Bourgade et al 2001). We limit the temperature gradient below 10% inside the foil in separating the incident ns beam in two parts, and inserting the foil between two cavities (Fig.…”

Section: First Lessons From Experimental Resultsmentioning

confidence: 99%

Seismology of Sun and stars and related opacity laboratory measurements

Turck‐Chièze

2012

EAS Publications Series

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Abstract. CNES, ESA and NASA have invested in helioseismic and asteroseismic disciplines for 2 decades with SoHO (1995SoHO ( -2015, COROT (2006COROT ( -2013, KEPLER (2009KEPLER ( -2014, PICARD (2010PICARD ( -2013 and SDO (2010SDO ( -2015. These missions focus on the stellar internal dynamics and their influence of neighboring planets. Progress along this path requires that the microscopic physics is well under control, but several seismic probes indicate some discrepancies which justify new investigations of the energy transport in radiative zones of the Sun and massive stars, despite strong efforts dedicated to reaction rates, screening, equation of state and opacity coefficients between 1990 and 2000. We describe here how the OPAC consortium tackles the complex problem of photon absorption by matter both theoretically and experimentally, by using high energy laser facilities. These studies might be also useful for other disciplines like fusion for energy and X-ray spectroscopy astronomy.

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Section: First Lessons From Experimental Resultsmentioning

confidence: 99%

Seismology of Sun and stars and related opacity laboratory measurements

Turck‐Chièze

2012

EAS Publications Series

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“…We measured the radiation temperature of the hohlraum using two wide-band X-ray spectrometers (µDMX and DMX) [2]. Two rear-side diagnostics measured the velocity and the self emission of the shock, respectively the VISAR [3,4] and the streaked optical self emission diagnostic.…”

Section: Methodsmentioning

confidence: 99%

Study of shock-coalescence on the LIL laser facility

Debras

Courtois

Lambert

et al. 2013

EPJ Web of Conferences

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Abstract. We use the LIL (Ligne d'Intégration Laser) facility to study the coalescence of two planar shocks in an indirectly-driven planar sample of polystyrene. This experiment represents the preliminary stage of the future shock-timing campaign for the Laser Megajoule (LMJ). The main objectives are to validate the experimental concept and to test the numerical simulations. We used a gold spherical hohlraum to convert into X-ray the 351 nm wavelength laser pulse and to initiate the two shocks in the sample. To access time resolved shock velocities and temperature, we used two rear-side diagnostics: a VISAR (Velocity Interferometer System for Any Reflection) working at two different wavelengths and a streaked optical selfemission diagnostic. We observed the coalesced shock, in good agreement with the numerical simulations. We also observed a loss of signal during the first nanoseconds probably due to sample heating from the hohlraum X-ray flux. CONTEXTThe LMJ, like the National Ignition Facility (NIF) in the USA, is designed to achieve thermonuclear ignition in an indirect drive scheme, by imploding a spherical capsule filled with a deuterium-tritium (DT) mixture. The best way to efficiently compress the fuel is quasi-isentropic compression. To approximate this compression, a series of four successive centripetal shocks are sent into the sample [1]. The shocks need to be accurately controlled in timing and strength to coalesce at the same time in the gaseous DT close to the inner surface of the cryogenic DT. The first three shocks allow compressing the capsule quasi-isentropically, keeping the cryogenic DT on a low adiabat. The fourth shock drives the final implosion until the ignition. This scheme requires to adjust the laser power time history entering in the gold hohlraum.In this experiment, we seeked to validate the experimental concept in planar geometry and indirect drive for the first two shocks using a truncated LMJ-like pulse shape and to compare the results with numerical simulations. EXPERIMENTAL SETUPFor this experiment we used the LIL laser facility at 3 (351 nm) with an energy of 10 kJ in 12 ns. A spherical gold hohlraum was used to obtain a radiation temperature similar to the first part of the nominal LMJ-drive. Two planar shocks are sent in a planar sample of polystyrene (PS -C 8 H 8 ) fixed on a

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“…The rapid expansion of the foil during the heating is limited by placing it between two thin samples of a low Z material, playing the role of inertial confinement to prevent a dramatic decrease of the density (see previous experiment [29]). In the experiments done at LULI 2000, we measure the radiative temperature of the X radiation in the cavity thanks to a multi channel spectrometer which measures X-rays energy [30]. We limit the temperature gradient below 10% inside the foil in separating the incident beam in two parts, and we then insert the foil between two cavities that are both heated by a similar flux.…”

Section: Comparison With Experimental Spectramentioning

confidence: 99%

News from the opacity consortium OPAC

Turck‐Chièze

Gilles

2013

EPJ Web of Conferences

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Abstract. The international OPAC consortium (see list below) was formed three years ago. It is composed of astrophysicists, plasma physicists and experimentalists from different laboratories b . This consortium examines specific opacity calculations used in stellar physics. They contribute to solve the problems suggested by the astrophysical community in performing new calculations and new experiments with laser installation. We show here the specific example of the iron opacity peak that plays an important role in the envelope of intermediate-mass and massive stars and we present our first conclusions on iron and nickel. OPEN PROBLEMS COMING FROM SEISMIC OBSERVATIONSThe stellar community hopes to progress on the internal dynamics of stars thanks to the space-borne seismic missions SoHO, CoRoT and Kepler. But good identification and interpretation of acoustic frequencies are based on a proper microscopic physics. Along the last decade, some questions on energy transfer, linked to plasma opacities, have arisen and two cases have retained our attention. 1. The extraction of the solar internal sound speed and density has revealed clear discrepancies with the Standard Solar Model predictions [1][2][3]. These discrepancies are not explained by the transport of momentum by rotation during the main sequence evolution [4]. So the energy balance and (or) energy transfer stay clearly under suspicion. In parallel, the recent OPAS calculations [5] have revealed large differences in individual element spectra with previous calculations and in particular with OP [6,7]. OPAS calculations also show some compensation effects between low Z nuclei and the iron group contributions in the Rosseland mean opacity values. All these facts encourage further works and experimental verifications. 2. The second case concerns massive stars. SPB and Cephei stars are interesting pulsators that might put important constraints on rotation and magnetic fields, two key actors for massive stars. Presently, the 40 stars observed by Kepler show acoustic and gravity modes probably up to = 20 (deformed stars) that are difficult to identify [8]. The first difficulty comes from the iron group opacities, which drive their pulsations. The observed modes do not agree with the stability of modes deduced from the OP or OPAL tables [9], which suggests that those opacities are underestimated [10,11]. Up to now, our effort is dedicated to the second case. The first analysis of the OPAC consortium confirms an underestimate of these opacities through comparison with more recent opacity calculations based on old and new measurements [12][13][14][15]. We shall here present our first conclusions and new orientations for the coming years.

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Erratum: “DMX: An absolutely calibrated time resolved broadband soft x-ray spectrometer designed for MJ class laser produced plasmas” [Rev. Sci. Instrum. 72, 1173 (2001)]

Cited by 17 publications

References 0 publications

Seismology of Sun and stars and related opacity laboratory measurements

Seismology of Sun and stars and related opacity laboratory measurements

Study of shock-coalescence on the LIL laser facility

News from the opacity consortium OPAC

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