Recent Progress in Fabrication of High-Strength Glow Discharge Polymer Shells by Optimization of Coating Parameters

Nikroo, A.; Czechowicz, D. G.; Castillo, E. R.; Pontelandolfo, J.M.

doi:10.13182/fst41-214

Cited by 28 publications

(7 citation statements)

References 7 publications

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“…21 These free radicals provide bonding sites for oxygen." 22,23 The oxygen density, presumably because of free radical creation, was shown in Ref. 20 to depend on exposure of the GDP to x-rays.…”

Section: Introductionmentioning

confidence: 97%

Instability growth seeded by oxygen in CH shells on the National Ignition Facility

et al. 2015

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Fusion targets imploded on the National Ignition Facility are subject to hydrodynamic instabilities. These have generally been assumed to be seeded primarily by surface roughness, as existing work had suggested that internal inhomogeneity was small enough not to contribute significantly. New simulations presented here examine this in more detail, and consider modulations in internal oxygen content in CH plastic ablators. The oxygen is configured in a way motivated by measurement of oxygen in the shells. We find that plausible oxygen nonuniformity, motivated by target characterization experiments, seeds instability growth that is 3-5Â bigger than expected from surface roughness. Pertinent existing capsule characterization is discussed, which suggests the presence of internal modulations that could be oxygen at levels large enough to be the dominant seed for hydrodynamic instability growth. Oxygen-seeded growth is smaller for implosions driven by high-foot pulse shapes, consistent with the performance improvement seen with these pulse shapes. Growth is somewhat smaller for planned future pulse shapes that were optimized to minimize growth of surface ripples. A possible modified specification for oxygen modulations is discussed, which is about 1/5 of the current requirement. V C 2015 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 97%

Instability growth seeded by oxygen in CH shells on the National Ignition Facility

et al. 2015

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“…(1) Existing JLab facilities in Virginia can be used to diffuse about 400 bar of molecular HD into 4 mm Ø Gas-Discharge-Polymer (GDP) shells, supplied by GA [25]. These will be cooled to a solid and transferred to a dilution refrigerator + superconducting magnet system, where they will be polarized at about 12 mK and 15 Tesla, using the techniques discussed in [26].…”

Section: Proof Of Principle Tests In a Research Tokamakmentioning

confidence: 99%

Polarized fusion, its Implications and plans for Direct Measurements in a Tokamak

Sandorfi,

Deur,

Hanretty

et al. 2017

Preprint

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Our energy-hungry world is burning. A long-term solution, possibly the only ultimate one, that is just approaching the horizon after decades of struggle, is fusion. Recent developments allow us to apply techniques from spin physics to advance the viability of this critical option. The cross section for the primary fusion fuel in a tokamak reactor, D+T → α+n, would be increased by a factor of 1.5 if the fuels were spin polarized parallel to the local field. Simulations predict further non-linear power gains in large-scale machines such as ITER, due to increased alpha heating. These are significant enhancements that could lower the requirements needed to reach ignition and could be used to extend useful reactor life by compensating for neutron degradation of critical components. The potential realization of such benefits rests on the survival of spin polarization for periods comparable to the energy containment time. Interest in polarized fuel options had an initial peak of activity in the 1980s, where calculations predicted that polarizations could in fact survive a plasma environment. However, concerns were raised regarding the cumulative impacts of fuel recycling from the reactor walls. In addition, the technical challenges of preparing and handling polarized materials prevented any direct tests. Over the last several decades, this situation has changed dramatically. Detailed simulations of the ITER plasma have projected negligible wall recycling in a high power reactor. In addition, a combination of advances in three areas -polarized material technologies developed for nuclear and particle physics as well as for medical imaging, polymer pellets developed for Inertial Confinement, and cryogenic injection guns developed for delivering fuel into the core of tokamaks -have matured to the point where a direct in situ measurement is possible. A Jefferson Lab -DIII-D/General Atomics -University of Virginia collaboration is developing designs for a proof-ofprinciple polarization survival experiment using the isospin mirror reaction, D + 3 He → α + p, at the DIII-D tokamak in San Diego.

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“…93.2 along with the NIF direct-drive ignition point design. The shell material is either strong GDP (a high-strength plastic) or CD 11 and is typically 5.0±0.1 µm thick. When permeation filled with approximately 1200 atm of D 2 and then cooled to the triple point (18.73 K), the resulting ice-layer thickness is 100 µm.…”

Section: Cryogenic Target Designmentioning

confidence: 99%

Direct-drive cryogenic target implosion performance on OMEGA

et al. 2003

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Layered and characterized cryogenic D2 capsules have been imploded using both low- and high-adiabat (α, the ratio of the electron pressure to the Fermi-degenerate pressure) pulse shapes on the 60-beam OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] at the Laboratory for Laser Energetics (LLE). These experiments measure the sensitivity of the direct-drive implosion performance to parameters such as the inner-ice-surface roughness, the adiabat of the cryogenic fuel during the implosion, the laser power balance, and the single-beam nonuniformity. The goal of the direct-drive program at LLE is to demonstrate a high neutron-averaged fuel ρR at a significant fraction of the predicted one-dimensional (1-D) neutron yield using an energy-scaled, low-adiabat (α∼3) ignition pulse shape driving a hydrodynamically scaled deuterium–tritium ignition capsule. New results are reported from implosions of ∼920-μm-diam, thin (∼5 μm) polymer shells containing 100 μm D2-ice layers with characterized inner-surface ice roughness of 3–12 μm rms. These capsules have been imploded using ∼17–23 kJ of 351 nm laser light with a beam-to-beam rms energy imbalance of less than 5% and full beam smoothing [1 THz bandwidth, two-dimensional (2-D) smoothing by spectral dispersion and polarization smoothing]. Near-1-D performance has been measured for a high-adiabat (α∼25) drive pulse, and the implosion performance with a low-adiabat (α∼4) pulse is in agreement with 2-D hydrocode predictions.

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Recent Progress in Fabrication of High-Strength Glow Discharge Polymer Shells by Optimization of Coating Parameters

Cited by 28 publications

References 7 publications

Instability growth seeded by oxygen in CH shells on the National Ignition Facility

Instability growth seeded by oxygen in CH shells on the National Ignition Facility

Polarized fusion, its Implications and plans for Direct Measurements in a Tokamak

Direct-drive cryogenic target implosion performance on OMEGA

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