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Title: Optics Recycle Loop Strategy for NIF Operations above UV Laser-Induced Damage Threshold

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) houses the world’s largest laser system, composed of 192 individual, 40-cm-aperture beamlines. The NIF laser routinely operates at ultraviolet (UV) fluences above 8 J/cm 2, more than twice the (3ω only) damage threshold of commercially available UV-grade fused silica. NIF is able to maintain such high fluence operation by using an optics recycling loop strategy. Successful operation of the loop relies on a number of technologies specifically developed for NIF. One of the most important is the capability developed by LLNL and their vendors for producing highly damage-resistant optics. Other technologies developed for the optics recycle loop raise the operating point of NIF by keeping damage growth in check. LLNL has demonstrated the capability to sustain UV fused silica optic recycling rates of up to 40 optics per week. The optics are ready for reinstallation after a 3-week trip through a recycle loop where the damage state of each optic is assessed and repaired. The impact of the optics recycle loop has been profound, allowing the experimental program to routinely employ energies and fluences that would otherwise have been unachievable. Without the recycle loop, it is likely that themore » NIF fluence would need to be kept below the UV threshold for damage growth, ~4 J/cm 2, thus keeping the energy delivered to the target significantly below 1 MJ. With the recycle loop implemented during the National Ignition Campaign, NIF can routinely deliver >1.8 MJ on target, an increase in operational capability of more than 100%. Finally, in this paper, the enabling technological advances, optical performance, and operational capability implications of the optics recycle loop are discussed.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)0
Publication Date:
Report Number(s):
LLNL-JRNL-658260
Journal ID: ISSN 1536-1055
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Fusion Science and Technology
Additional Journal Information:
Journal Volume: 69; Journal Issue: 1; Journal ID: ISSN 1536-1055
Publisher:
American Nuclear Society
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE; LLNL Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 42 ENGINEERING; lasers and laser optics; laser damage; pulsed lasers; UV lasers
OSTI Identifier:
1259762

Spaeth, M. L., Wegner, P. J., Suratwala, T. I., Nostrand, M. C., Bude, J. D., Conder, A. D., Folta, J. A., Heebner, J. E., Kegelmeyer, L. M., MacGowan, B. J., Mason, D. C., Matthews, M. J., and Whitman, P. K.. Optics Recycle Loop Strategy for NIF Operations above UV Laser-Induced Damage Threshold. United States: N. p., Web. doi:10.13182/FST15-119.
Spaeth, M. L., Wegner, P. J., Suratwala, T. I., Nostrand, M. C., Bude, J. D., Conder, A. D., Folta, J. A., Heebner, J. E., Kegelmeyer, L. M., MacGowan, B. J., Mason, D. C., Matthews, M. J., & Whitman, P. K.. Optics Recycle Loop Strategy for NIF Operations above UV Laser-Induced Damage Threshold. United States. doi:10.13182/FST15-119.
Spaeth, M. L., Wegner, P. J., Suratwala, T. I., Nostrand, M. C., Bude, J. D., Conder, A. D., Folta, J. A., Heebner, J. E., Kegelmeyer, L. M., MacGowan, B. J., Mason, D. C., Matthews, M. J., and Whitman, P. K.. 2017. "Optics Recycle Loop Strategy for NIF Operations above UV Laser-Induced Damage Threshold". United States. doi:10.13182/FST15-119. https://www.osti.gov/servlets/purl/1259762.
@article{osti_1259762,
title = {Optics Recycle Loop Strategy for NIF Operations above UV Laser-Induced Damage Threshold},
author = {Spaeth, M. L. and Wegner, P. J. and Suratwala, T. I. and Nostrand, M. C. and Bude, J. D. and Conder, A. D. and Folta, J. A. and Heebner, J. E. and Kegelmeyer, L. M. and MacGowan, B. J. and Mason, D. C. and Matthews, M. J. and Whitman, P. K.},
abstractNote = {The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) houses the world’s largest laser system, composed of 192 individual, 40-cm-aperture beamlines. The NIF laser routinely operates at ultraviolet (UV) fluences above 8 J/cm2, more than twice the (3ω only) damage threshold of commercially available UV-grade fused silica. NIF is able to maintain such high fluence operation by using an optics recycling loop strategy. Successful operation of the loop relies on a number of technologies specifically developed for NIF. One of the most important is the capability developed by LLNL and their vendors for producing highly damage-resistant optics. Other technologies developed for the optics recycle loop raise the operating point of NIF by keeping damage growth in check. LLNL has demonstrated the capability to sustain UV fused silica optic recycling rates of up to 40 optics per week. The optics are ready for reinstallation after a 3-week trip through a recycle loop where the damage state of each optic is assessed and repaired. The impact of the optics recycle loop has been profound, allowing the experimental program to routinely employ energies and fluences that would otherwise have been unachievable. Without the recycle loop, it is likely that the NIF fluence would need to be kept below the UV threshold for damage growth, ~4 J/cm2, thus keeping the energy delivered to the target significantly below 1 MJ. With the recycle loop implemented during the National Ignition Campaign, NIF can routinely deliver >1.8 MJ on target, an increase in operational capability of more than 100%. Finally, in this paper, the enabling technological advances, optical performance, and operational capability implications of the optics recycle loop are discussed.},
doi = {10.13182/FST15-119},
journal = {Fusion Science and Technology},
number = 1,
volume = 69,
place = {United States},
year = {2017},
month = {3}
}