Measuring the absolute deuterium–tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

Casey, D. T.; Frenje, J. A.; Johnson, M. Gatu; Séguin, F.H.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Katz, J.; Knauer, J. P.; Meyerhofer, D. D.; Sangster, T. C.; Bionta, R. M.; Bleuel, D. L.; Döppner, T.; Glenzer, S. H.; Hartouni, E. P.; Hatchett, S.; Pape, S. Le; Ma, T.; Mackinnon, A. J.; McKernan, M. A.; Moran, Mike; Moses, E. I.; Park, H.-S.; Ralph, J. E.; Remington, B. A.; Smalyuk, V. A.; Yeamans, C. B.; Kline, J. L.; Kyrala, G. A.; Chandler, G. A.; Leeper, R. J.; Ruiz, C. L.; Cooper, G. W.; Nelson, A. J.; Fletcher, K.; Kilkenny, J. D.; Farrell, M.; Jasion, Daniel; Paguio, R. R.

doi:10.1063/1.4738657

Cited by 36 publications

(8 citation statements)

References 21 publications

(20 reference statements)

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“…The neutron yield and ion temperature are measured by a suite of neutron time-of-flight detectors [27], neutron activation diagnostics [28], and the magnetic recoil spectrometer [29]. Hot spot volume is determined from gated FIG.…”

mentioning

confidence: 99%

Onset of Hydrodynamic Mix in High-Velocity, Highly Compressed Inertial Confinement Fusion Implosions

Ma¹,

Patel²,

Izumi³

et al. 2013

Phys. Rev. Lett.

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226

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Deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility have demonstrated yields ranging from 0.8 to 7×10(14), and record fuel areal densities of 0.7 to 1.3 g/cm2. These implosions use hohlraums irradiated with shaped laser pulses of 1.5-1.9 MJ energy. The laser peak power and duration at peak power were varied, as were the capsule ablator dopant concentrations and shell thicknesses. We quantify the level of hydrodynamic instability mix of the ablator into the hot spot from the measured elevated absolute x-ray emission of the hot spot. We observe that DT neutron yield and ion temperature decrease abruptly as the hot spot mix mass increases above several hundred ng. The comparison with radiation-hydrodynamic modeling indicates that low mode asymmetries and increased ablator surface perturbations may be responsible for the current performance.

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confidence: 99%

Onset of Hydrodynamic Mix in High-Velocity, Highly Compressed Inertial Confinement Fusion Implosions

Ma¹,

Patel²,

Izumi³

et al. 2013

Phys. Rev. Lett.

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226

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“…Capsule x-ray bang times 30,31 were $22.55 6 0.10 ns, all within 100 ps. We will focus upon capsule performance metrics of DT, DD, TT neutron yield, [32][33][34] neutron time-of-flight measurements 35 of ion temperature 36 and down-scatter ratio (DSR), temporal burn width from x-rays 37 or DT gammas, 38,39 and x-ray 40 and neutron image size and shape. 41 DSR is the ratio of neutrons in the 10-12 MeV energy range to those in the 13-15 MeV range, and is diagnostic of fuel column density.…”

Section: Simulations Of Implosions With CD Layersmentioning

confidence: 99%

Simulations of indirectly driven gas-filled capsules at the National Ignition Facility

et al. 2014

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Gas-filled capsules imploded with indirect drive on the National Ignition Facility have been employed as symmetry surrogates for cryogenic-layered ignition capsules and to explore interfacial mix. Plastic capsules containing deuterated layers and filled with tritium gas provide a direct measure of mix of ablator into the gas fuel. Other plastic capsules have employed DT or D3He gas fill. We present the results of two-dimensional simulations of gas-filled capsule implosions with known degradation sources represented as in modeling of inertial confinement fusion ignition designs; these are time-dependent drive asymmetry, the capsule support tent, roughness at material interfaces, and prescribed gas-ablator interface mix. Unlike the case of cryogenic-layered implosions, many observables of gas-filled implosions are in reasonable agreement with predictions of these simulations. Yields of TT and DT neutrons as well as other x-ray and nuclear diagnostics are matched for CD-layered implosions. Yields of DT-filled capsules are over-predicted by factors of 1.4–2, while D3He capsule yields are matched, as well as other metrics for both capsule types.

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“…The efficiency of the MRS can be accurately calculated from first principles, allowing the MRS to provide a solid, independent Y n measurement. 23 Spectral broadening due to geometry, CD 2 foil thickness, and magnet properties determines the spectrometer resolution. In standard fashion, the efficiency can be increased at the expense of resolution by using a thicker CD 2 foil.…”

Section: A Mrsmentioning

confidence: 99%

Neutron spectrometry—An essential tool for diagnosing implosions at the National Ignition Facility (invited)

Johnson

Frenje

Casey

et al. 2012

Review of Scientific Instruments

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126

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DT neutron yield (Y(n)), ion temperature (T(i)), and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of inertial confinement fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-time-of-flight (nTOF) spectrometers and a magnetic recoil spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the complementarity required for reliable measurements of Y(n), T(i), and dsr. From the measured dsr value, an areal density (ρR) is determined through the relationship ρR(tot) (g∕cm(2)) = (20.4 ± 0.6) × dsr(10-12 MeV). The proportionality constant is determined considering implosion geometry, neutron attenuation, and energy range used for the dsr measurement. To ensure high accuracy in the measurements, a series of commissioning experiments using exploding pushers have been used for in situ calibration of the as-built spectrometers, which are now performing to the required accuracy. Recent data obtained with the MRS and nTOFs indicate that the implosion performance of cryogenically layered DT implosions, characterized by the experimental ignition threshold factor (ITFx), which is a function of dsr (or fuel ρR) and Y(n), has improved almost two orders of magnitude since the first shot in September, 2010.

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Measuring the absolute deuterium–tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

Cited by 36 publications

References 21 publications

Onset of Hydrodynamic Mix in High-Velocity, Highly Compressed Inertial Confinement Fusion Implosions

Onset of Hydrodynamic Mix in High-Velocity, Highly Compressed Inertial Confinement Fusion Implosions

Simulations of indirectly driven gas-filled capsules at the National Ignition Facility

Neutron spectrometry—An essential tool for diagnosing implosions at the National Ignition Facility (invited)

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