Soft x-ray images of the laser entrance hole of ignition hohlraums

Schneider, M. B.; Meezan, N. B.; Alvarez, S. S.; Alameda, Jennifer B.; Baker, Sherry L.; Bell, P. M.; Bradley, D. K.; Callahan, D. A.; Celeste, J.; Dewald, E. L.; Dixit, S. N.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Fernández-Perea, Mónica; Gullikson, Eric M.; Haugh, M. J.; Hau-Riege, S. P.; Hsing, W. W.; Izumi, N.; Jones, O. S.; Kalantar, D. H.; Kilkenny, J. D.; Kline, J. L.; Kyrala, G. A.; Landen, O. L.; London, Richard A.; MacGowan, B. J.; Mackinnon, A. J.; McCarville, T.; Milovich, J. L.; Mirkarimi, Paul B.; Moody, J. D.; Moore, A. S.; Myers, M. D.; Palma, Elizabeth; Palmer, N. E.; Pivovaroff, M. J.; Ralph, J. E.; Robinson, Jeffrey C.; Soufli, Régina; Suter, L. J.; Teruya, Alan T.; Thomas, C. A.; Town, R. P. J.; Vernon, S. P.; Widmann, K.; Young, B. K.

doi:10.1063/1.4732850

Cited by 24 publications

(3 citation statements)

References 8 publications

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“…The polar first mode (m = 0) size M 0 is calculated from the 17% contour of the image viewed from the upper NIF pole. Secondary measurements are taken in spatially integrated, time-resolved x ray emission [70,71]; time-integrated x-ray imaging [72,73]; and occasionally in-flight shell x-ray radiography. The coast time is defined as the interval between the requested end of the laser flattop and the neutron bang time.…”

Section: Metrics and Diagnosticsmentioning

confidence: 99%

High yield polar direct drive fusion neutron sources at the National Ignition Facility

et al. 2021

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Polar direct drive neutron source experiments were performed at the National Ignition Facility showing substantial improvement in total neutron yield and efficiency of conversion of laser energy to fusion output. Plastic capsules 3–4 mm in diameter were filled with 1.5 mg/cc of deuterium–tritium (DT) fuel and imploded with laser beam pointing and defocus designed to compensate for polar asymmetry introduced by the facility beam entrance angles. Radiation-hydrodynamics simulations were employed to optimize the multi-dimensional laser and target parameter space, within facility and target fabrication constraints. Ensembles of 1D simulations tuned to match the outputs of early shots in the series were used to design subsequent shots in the series. This allowed the later shots to be designed based on empirically motivated sensitivities to laser and target input parameters, while eliminating the need to explicitly model phenomena such as hydrodynamic instabilities and nonlinear laser–plasma interactions. One experiment with a 3.0 mm diameter CH capsule produced 13.6 kJ (4.81 × 1015 DT neutrons) from a laser input below the NIF optics damage threshold at 585 kJ, 328 TW. Two experiments with 4.0 mm capsules produced 31.3 and 33.6 kJ of fusion output (1.11 × 1016 and 1.19 × 1016 DT neutrons) with 1.10 MJ, 390 TW and 1.26 MJ, 425 TW of laser input, respectively.

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Section: Metrics and Diagnosticsmentioning

confidence: 99%

High yield polar direct drive fusion neutron sources at the National Ignition Facility

et al. 2021

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“…The hohlraum drive is measured by a time-resolved absolutely calibrated multispectral channel soft x-ray diode array ('Dante') [29,30] through the bottom Laser Entrance Hole (LEH) at an angle of 37 axis. The measured peak powers of 15-20 TW sr −1 are converted to a Planckian radiation temperature by dividing by the measured LEH area [31,32] which closes in time and applying a <10 eV calculated viewfactor correction to translate between fluxes measured by Dante and the flux impinging on average on the capsule [33]. Figure 3(b) plots the peak radiation temperatures thus inferred versus absorbed laser energy, showing the expected improvement in Tr using higher albedo uranium wall hohlraums [34][35][36], exceeding the initial goal of 300 eV for over 1 MJ absorbed laser energy.…”

Section: Hohlraum Drivementioning

confidence: 99%

Progress in the indirect-drive National Ignition Campaign

Landen

Benedetti

Bleuel

et al. 2012

Plasma Phys. Control. Fusion

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We have carried out precision optimization of inertial confinement fusion ignition scale implosions. We have achieved hohlraum temperatures in excess of the 300 eV ignition goal with hot-spot symmetry and shock timing near ignition specs. Using slower rise pulses to peak power and extended pulses resulted in lower hot-spot adiabat and higher main fuel areal density at about 80% of the ignition goal. Yields are within a factor of 5-6 of that required to initiate alpha dominated burn. It is likely we will require thicker shells (+15-20%) to reach ignition velocity without mixing of ablator material into the hot spot.

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“…The Static X-Ray Imager (SXI) is a National Ignition Facility (NIF)diagnostic used to record time-integrated X-ray images.While its primary use is to measure changes in the size of the hohlraum's laser entrance holes (LEH) [1], it has also been used as a diagnostic in laser pointing shots and other experiments. The SXI works on the same principal as the classic pinhole camera except that it records X-ray photons instead of visible light.…”

Section: Introductionmentioning

confidence: 99%