Thermal and Structural Issues of Target Injection into a Laser-Driven Inertial Fusion Energy Chamber

Miles, Robin R.; Chang, Ansi; Fornasiero, Francesco; Havstad, Mark; Kucheyev, S. O.; LeBlanc, M.M.; Rosso, Paul A.; Schebler, Greg

doi:10.13182/fst14-779

Cited by 2 publications

(1 citation statement)

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“…Unwanted heating of sensitive surfaces in harsh thermal environments is observed at the ends of high power lasers, on the front of planetary probes on reentry, on the interior of viewports in plasma coating vessels and in numerous other applications. In an IFE application, polyimide membrane is used for the laser entrance hole (LEH) window positioned at the leading and trailing surfaces of an inertial fusion confinement target shown in Figure 1 [1]. The target is designed to be injected into a fusion chamber containing hot, low pressure xenon gas (6000K, 23 torr).…”

Section: Introductionmentioning

confidence: 99%

Transient thermal protection of film covering circular aperture by sublimation and weak decomposition

Havstad

Miles

Hsieh

2015

Fusion Engineering and Design

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Unwanted heating of sensitive surfaces in harsh thermal environments can be prevented by precise application of sacrificial materials such as sublimation layers and pyrolyzing films. The use of sublimation for the protection of circular polyimide membranes subjected to brief (~100 msec) heating by infrared radiation and hot (6000 K) inert gas convection is analyzed. Selection of sublimation material and sublimation layer and membrane thickness is considered with emphasis on providing sufficient thermal protection yet negligible unwanted material remaining at the end of a specified heating period. Though the analysis here is general, the motivation is protection of the polyimide films covering the laser entrance holes on IFE (inertial fusion energy) hohlraums being injected into the hot gas (xenon) protecting IFE reactor chambers.Both one and two dimensional thermal models are used to develop a robust thermal concept.Sensitivity analyses (SA) methods are exercised to show where the design may be vulnerable and which input parameters have the greatest effect on performance and likelihood of success. For the design and conditions considered, methane sublimating layers are probably preferred over xenon or pentane.

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Section: Introductionmentioning

confidence: 99%