Adapting the Decomposable Mandrel Technique to Build Specialty ICF Targets

Fearon, E. M.; Letts, Stephan A.; Allison, Leslie M.; Cook, Robert

doi:10.13182/fst97-a30793

Cited by 11 publications

(4 citation statements)

References 7 publications

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“…A similar phenomenon of more cracks and a higher permeability for a thicker film has been observed for 50-and 100-Å Ti coatings over poly-α-methyl styrene. 21 During these experiments, it was noticed that the measured Ar fill pressure was lower at initial time than expected from the Ar leak rate. Consequently, a second set of fill experiments was conducted, and the time constant for filling was estimated from the increase in Ar signal.…”

Section: Permeability Measurementsmentioning

confidence: 87%

Evaulation of B{sub 4}C as an ablator material for NIF capsules. Revision 1

Burnham¹,

Alford²,

Makowiecki³

et al. 1997

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Boron carbide (B 4 C) is examined as a potential fuel container and ablator for implosion capsules on the National Ignition Facility (NIF). A capsule of pure B 4 C encasing a layer of solid DT implodes stably and ignites with anticipated NIF x-ray drives, producing 18 MJ of energy. Thin films of B 4 C were found to be resistant to oxidation and modestly transmitting in the infrared (IR), possibly enabling IR fuel characterization and enhancement for thin permeation barriers but not for full-thickness capsules. Polystyrene mandrels 0.5 mm in diameter were successfully coated with 0.15-2.0 µm of B 4 C. Thicknesses estimated from optical density agreed well with those measured by scanning electron microscopy (SEM). The B 4 C microstructure was columnar but finer than for Be made at the same conditions. B 4 C is a very strong material, with a fiber tensile strength capable of holding NIF fill pressures at room temperature, but it is also very brittle, and microscopic flaws or grain structure may limit the noncryogenic fill pressure. Argon (Ar) permeation rates were measured for a few capsules that had been further coated with 5 µm of plasma polymer. The B 4 C coatings tended to crack under tensile load. Some shells filled more slowly than they leaked, suggesting that the cracks open and close under opposite pressure loading. As observed earlier for Ti coatings, 0.15-µm layers of B 4 C had better gas retention properties than 2-µm layers, possibly because of fewer cracks. Permeation and fill strength issues for capsules with a full ablator thickness of B 4 C are unresolved.

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Section: Permeability Measurementsmentioning

confidence: 87%

Evaulation of B{sub 4}C as an ablator material for NIF capsules. Revision 1

Burnham¹,

Alford²,

Makowiecki³

et al. 1997

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“…For a PaMS system with chain length D p , the non-breaking probability of all CeC particles (bonds) in a main chain and a characteristic time t is ð1 À PðTÞÞ DpÀ1 (10) Assume N(t) chains contained in a PaMS system at time t, and then the number of remaining chains of the N(t) chains after a characteristic time t is Nðt þ tÞ ¼ NðtÞð1 À PðTÞÞ DpÀ1 (11) The vibrational motions cause that the atoms of PaMS deviate away from the equilibrium positions. The binding force that bonds atoms goes down with the deviation.…”

Section: The Kinetic Equation Of Polymer Thermal Decompositionmentioning

confidence: 99%

A molecular based kinetic study on the thermal decomposition of poly-α-methyl styrene

Sun

Jiang

et al. 2014

Polymer Degradation and Stability

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“…Among the multiple parts of ICF experiments, target is essential, whose quality has an extremely important influence on the reliability and degree of precision for subsequent experimental results ( Tucker-Schwartz et al., 2010 ; Antipa et al., 2013 ). In recent years, the degradable mandrel technique with poly-α-methylstyrene (PAMS) degradation as the core has become one of the main technologies for fabricating high-quality ICF targets ( Letts et al, 1995 ; Fearon et al., 1997 ). For this technology, one key problem is how to achieve effective degradation of PAMS.…”

Section: Introductionmentioning

confidence: 99%

Quantum tunneling of hydrogen atom transfer affects mandrel degradation in inertial confinement fusion target fabrication

Zhu

Yang

et al. 2022

iScience

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Summary Poly-α-methylstyrene (PAMS) is considered as the preferred mandrel material, whose degradation is crucial for the fabrication of high-quality inertial confinement fusion (ICF) targets. Herein, we reveal that hydrogen atom transfer (HAT) during PAMS degradation, which is usually attributed to the thermal effect, unexpectedly exhibits a strong high-temperature tunneling effect. Specifically, although the energy barrier of the HAT reaction is only 10 −2 magnitude different from depolymerization, the tunneling probability of the former can be 14–32 orders of magnitude greater than that of the latter. Furthermore, chain scission following HAT will lead to a variety of products other than monomers. Our work highlights that quantum tunneling may be an important source of uncertainty in PAMS degradation, which will provide a direction for the further development of key technology of target fabricating in ICF research and even the solution of plastic pollution.

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Adapting the Decomposable Mandrel Technique to Build Specialty ICF Targets

Cited by 11 publications

References 7 publications

Evaulation of B{sub 4}C as an ablator material for NIF capsules. Revision 1

Evaulation of B{sub 4}C as an ablator material for NIF capsules. Revision 1

A molecular based kinetic study on the thermal decomposition of poly-α-methyl styrene

Quantum tunneling of hydrogen atom transfer affects mandrel degradation in inertial confinement fusion target fabrication

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