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Title: Prevention of Residual Gas Condensation on the Laser Entry Hole Windows on Cryogenic NIF Targets Using a Protective Warm Film

Journal Article · · Fusion Science and Technology
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  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
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Many of the early cryogenic shots on NIF were plagued by buildup of considerable mass of extraneous ice on the LEH windows, a consequence of condensation of the residual air in the surrounding chamber. Thickness of this ice depended on the exact chamber pressure and the target fielding time duration, both extremely difficult to keep constant given the broad range of target types being shot. In this paper, we describe our work in designing a robust solution in the form of a second thin film that shielded the LEH window from the contaminating ice. Several detailed cryogenic considerations were required to ensure the proper functioning of this new window, which were simulated and verified experimentally. Data from numerous subsequent shots showed marked improvement in performance, which made this new feature an essential component for all cryogenic NIF targets.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1430923
Report Number(s):
LLNL-JRNL-737820; TRN: US1802638
Journal Information:
Fusion Science and Technology, Vol. 73, Issue 3; ISSN 1536-1055
Publisher:
American Nuclear SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 1 work
Citation information provided by
Web of Science

References (14)

Status of cryogenic layering for NIF ignition targets journal May 2008
Modeling and Experiments of Compressible Gas Flow Through Microcapillary Fill Tubes on NIF Targets journal January 2011
Constitutive Models for the Viscoelastic Behavior of Polyimide Membranes at Room and Deep Cryogenic Temperatures journal September 2016
Ignition on the National Ignition Facility: a path towards inertial fusion energy journal September 2009
The physics basis for ignition using indirect-drive targets on the National Ignition Facility journal February 2004
Laser Entrance Hole Window Burst and Pressure Deflections at Cryogenic Temperature journal January 2011
Solid deuterium–tritium surface roughness in a beryllium inertial confinement fusion shell journal December 2006
Experimental D-T Ice-Layering Target Assembly journal April 2009
Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums journal February 2016
Target Development for the National Ignition Campaign journal February 2016
Cryogenic Target System for Hydrogen Layering journal February 2016
Cryogenic DT and D2 targets for inertial confinement fusion journal May 2007
Design of the NIF Cryogenic Target System journal April 2009
Measurement of Total Condensation on a Shrouded Cryogenic Surface Using a Single Quartz Crystal Microbalance journal April 2009

Figures / Tables (13)

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Figure 11(p. 18)figure Figure 11
Figure 12(p. 19)figure Figure 12
Figure 13(p. 20)figure Figure 13

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Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION