Fabrication of special inertial confinement fusion targets using a depolymerizable mandrel technique

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

doi:10.1116/1.580124

Cited by 15 publications

(3 citation statements)

References 3 publications

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“…Smaller shells for previous and ongoing laser experiments have been made previously by drop tower techniques, interracial reactions (Arshady, 1989;Takagi, 1993;Letts, 1996;Hamilton, 1997), ballistic furnace methods (Merkuliev, 1995;Nikitenko, 1997), and microencapsulation. Drop tower approaches suftler from transport limitations (in scaling from 0.5-mm diameter to 2.0 mm diameter).…”

Section: Introductionmentioning

confidence: 99%

“…Details of vacuole formation and the associated phase separation have been investigated previously (Wilemski, 1995;Boone, 1995). Because we are implementing a decomposable mandrel approach (Letts, 1995a;1995b;1996), vacuoles are not an issue for us (provided their formation does not affect the exterior shell surface), and they will not be discussed further in any great detail.…”

Section: Introductionmentioning

confidence: 99%

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Science of NIF scale capsule development (activities for FY97)

Hamilton¹,

Buckley²,

Cook³

1997

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The focus of this work is the production of 2-mm PczMS mandrels by microencapsulation for use as National Ignition Facility (NH?) laser targets. It is our findings thus far that the processing techniques used previously for the 0.5mm and I.O-mm targets are no longer usefid for preparation of the larger targets for a few fundamental reasons. The driving force for sphericity (from the minimization of interracial energy) decreases as the radius of curvature increases. Simultaneously, the mechanical robustness /stability of the wateroil-water emulsion droplets decreases as the droplet size increases. The impact of these physical conditions and the possibilities of circumventing these limitations have been examined while attempting to meet the NIF shell power spectrum criteria. Identi&ing the key parameters in the transition (solidification) from a w-o-w droplet to a solid polymer shell has been understood implicitly to be the paramount goal. It is believed through the knowledge gained that it will be possible to minimize the deleterious forces and maximize shell sphericity. At this point it is believed that properties intrinsic to the polymer (i.e., PcxMS) such as its solution behavior and evolution of iilm stresses control the overall shell sphericity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Science of NIF scale capsule development (activities for FY97)

Hamilton¹,

Buckley²,

Cook³

1997

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“…1,2,3 The central row of Figure 1 shows the basic process. A shell of poly(α-methyl styrene) (PAMS) produced by microencapsulation is overcoated with plasma polymer (CH).…”

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confidence: 99%

Adapting the Decomposable Mandrel Technique to Build Specialty ICF Targets

et al. 1997

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Fearon Page 1 of 5 ABSTRACTIn this paper we describe our efforts to produce ICF target capsules with either controlled inner surface roughness or thin metallic diagnostic layers by adapting the decomposable mandrel technique previously developed at LLNL. To modify the capsule's inner surface we laser ablated a pattern on a poly(α-methylstyrene) (PAMS) shell, overcoated it with plasma polymer and then thermally decomposed the inner mandrel to leave the plasma polymer shell with the imprint of the laser ablated mandrel pattern. In this fashion we have been able to produce shells with controlled inner surface bumps. However, these bumps are correlated with outer surface pits. To place a thin metallic diagnostic layer on the inner capsule surface we applied a 50 Å titanium sputter coating to a smooth PAMS shell, overcoated with plasma polymer, and then thermally decomposed the mandrel to leave a plasma polymer shell with the titanium layer on the inner surface. Surface analysis showed that this process resulted in shells with a relatively long wavelength roughness, possibly due to the action of the metallic layer as a permeation barrier.

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Reactive molecular dynamics simulations on the thermal decomposition of poly alpha-methyl styrene

Sun

et al. 2017

J Mol Model

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Using molecular dynamics simulations with ReaxFF reactive force field, the thermal decomposition mechanism of poly alpha-methyl styrene (PAMS) materials and the effects of heating rate and impurity fluorobenzene on PAMS thermal decompositions are studied. The results show that: 1) Pyrolysis mechanism of PAMS consists of initiation and propagation processes. In the initiation stage, random scissions of C-C backbone produce fragments, and in the propagation stage, depolymerizing reactions generate monomers and other products. 2) Higher decomposition temperature is needed for greater heating rate. 3) The presence of impurity fluorobenzene retards thermal decomposition of PAMS.

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Fabrication of special inertial confinement fusion targets using a depolymerizable mandrel technique

Cited by 15 publications

References 3 publications

Science of NIF scale capsule development (activities for FY97)

Science of NIF scale capsule development (activities for FY97)

Adapting the Decomposable Mandrel Technique to Build Specialty ICF Targets

Reactive molecular dynamics simulations on the thermal decomposition of poly alpha-methyl styrene

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