A series of cryogenic, layered deuterium-tritium (DT) implosions have produced, for the first time, fusion energy output twice the peak kinetic energy of the imploding shell. These experiments at the ...National Ignition Facility utilized high density carbon ablators with a three-shock laser pulse (1.5 MJ in 7.5 ns) to irradiate low gas-filled (0.3 mg/cc of helium) bare depleted uranium hohlraums, resulting in a peak hohlraum radiative temperature ∼290 eV. The imploding shell, composed of the nonablated high density carbon and the DT cryogenic layer, is, thus, driven to velocity on the order of 380 km/s resulting in a peak kinetic energy of ∼21 kJ, which once stagnated produced a total DT neutron yield of 1.9×10^{16} (shot N170827) corresponding to an output fusion energy of 54 kJ. Time dependent low mode asymmetries that limited further progress of implosions have now been controlled, leading to an increased compression of the hot spot. It resulted in hot spot areal density (ρr∼0.3 g/cm^{2}) and stagnation pressure (∼360 Gbar) never before achieved in a laboratory experiment.
The impact to fusion energy production due to the radiative loss from a localized mix in inertial confinement implosions using high density carbon capsule targets has been quantified. The radiative ...loss from the localized mix and local cooling of the reacting plasma conditions was quantified using neutron and x-ray images to reconstruct the hot spot conditions during thermonuclear burn. Such localized features arise from ablator material that is injected into the hot spot from the Rayleigh-Taylor growth of capsule surface perturbations, particularly the tube used to fill the capsule with deuterium and tritium fuel. Observations, consistent with analytic estimates, show the degradation to fusion energy production to be linearly proportional to the fraction of the total emission that is associated with injected ablator material and that this radiative loss has been the primary source of variations, of up to 1.6 times, in observed fusion energy production. Reducing the fill tube diameter has increased the ignition metric χ_{no α} from 0.49 to 0.72, 92% of that required to achieve a burning hot spot.
We have developed an experimental platform for the National Ignition Facility that uses spherically converging shock waves for absolute equation-of-state (EOS) measurements along the principal ...Hugoniot. In this Letter, we present one indirect-drive implosion experiment with a polystyrene sample that employs radiographic compression measurements over a range of shock pressures reaching up to 60 Mbar (6 TPa). This significantly exceeds previously published results obtained on the Nova laser R. Cauble et al., Phys. Rev. Lett. 80, 1248 (1998)PRLTAO0031-900710.1103/PhysRevLett.80.1248 at a strongly improved precision, allowing us to discriminate between different EOS models. We find excellent agreement with Kohn-Sham density-functional-theory-based molecular dynamics simulations.
Evolution of the hot spot plasma conditions was measured using high-resolution x-ray spectroscopy at the National Ignition Facility. The capsules were filled with DD gas with trace levels of Kr and ...had either a high-density-carbon (HDC) ablator or a tungsten (W)-doped HDC ablator. Time-resolved measurement of the Kr Heβ spectra, absolutely calibrated by a simultaneous time-integrated measurement, allows inference of the electron density and temperature through observing Stark broadening and the relative intensities of dielectronic satellites. By matching the calculated hot spot emission using a collisional-radiative code to experimental observations, the hot spot size and areal density are determined. These advanced spectroscopy techniques further reveal the effect of W dopant in the ablator on the hot spot parameters for their improved implosion performance.
Ignition is needed to make fusion energy a viable alternative energy source, but has yet to be achieved. A key step on the way to ignition is to have the energy generated through fusion reactions in ...an inertially confined fusion plasma exceed the amount of energy deposited into the deuterium-tritium fusion fuel and hotspot during the implosion process, resulting in a fuel gain greater than unity. Here we report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a 'high-foot' implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion. These experiments show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite.
The concept of hepatorenal syndrome is well recognized, although incompletely understood. The converse clinical problem of hepatic dysfunction in patients with acute kidney injury (AKI) is less well ...recognized yet may be a contributor to the high patient morbidity and mortality seen in this group. This review draws together the available evidence for AKI's effect on the liver from animal models, pharmacological studies and recent clinical data. It examines liver function beyond clinically used blood tests, to determine the effect of AKI on hepatic synthetic function, acute phase response and drug metabolism. Parallels are drawn with other organ crosstalk in AKI and with liver-kidney interactions in chronic kidney disease. Definition of the pathophysiology of renohepatic crosstalk may lead to improved management strategies for this vulnerable patient group.
Introduction
Acute kidney injury (AKI) is a common and serious complication increasing morbidity and mortality from all causes of hospital admission. We have previously shown that AKI decreases ...midazolam metabolism, a substrate of the cytochrome P450 3A (CYP3A) enzymes and our primary aim was to determine if this effect is dependent on the severity of AKI. We also present preliminary data on the functional impact of different genotypes of CYP3A.
Methods
Critically ill patients at risk of AKI and admitted to a general intensive care unit were categorised after initial resuscitation according to the RIFLE criteria for AKI. Midazolam (1mg) was administered and the serum concentration of midazolam measured at 4 h. Samples were taken for CYP3A genotyping.
Results
Seventy-three patients were assigned to categories R, I and F of the RIFLE criteria or C (controls). Midazolam concentrations (ng mL
−1
) increased significantly (
p
= 0.002) as the severity of AKI worsened control 3.1 (1.4–5.9), risk 4.7 (1.3–10.3), injury 3.9 (2.0–11.1) and failure 6.8 (2.2–113.6) and were predicted by the duration of AKI (
p
= 0.000) and γ-glutamyl transferase (p = 0.005) concentrations. Increasing BMI negatively predicted the midazolam concentration (
p
= 0.001). Preliminary data suggest this effect is diminished if the patient expresses functional CYP3A5.
Conclusion
Increasing severity and duration of AKI are associated with decreased midazolam elimination. We propose that this is caused by impaired CYP3A activity secondary to AKI. The exact mechanism remains to be elucidated. This may have important implications for our drug treatment of critically ill patients.
Direct measurements of hydrodynamic instability growth at the fuel-ablator interface in inertial confinement fusion (ICF) implosions are reported for the first time. These experiments investigate one ...of the degradation mechanisms behind the lower-than-expected performance of early ICF implosions on the National Ignition Facility. Face-on x-ray radiography is used to measure instability growth occurring between the deuterium-tritium fuel and the plastic ablator from well-characterized perturbations. This growth starts in two ways through separate experiments-either from a preimposed interface modulation or from ablation front feedthrough. These experiments are consistent with analytic modeling and radiation-hydrodynamic simulations, which say that a moderately unstable Atwood number and convergence effects are causing in-flight perturbation growth at the interface. The analysis suggests that feedthrough from outersurface perturbations dominates the interface perturbation growth at mode 60.
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