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Title: An analysis of grazing incidence metal mirrors in a laser ICF reactor driver

Abstract

Grazing incidence metal mirrors (GIMMs) are examined to replace dielectric mirrors for the final elements in a laser beam line for an inertial confinement fusion reactor. For a laser driver with a wavelength from 250 to 500 nm in a 10-ms pulse, irradiated mirrors made of Al, Al alloys, or Mg were found to have calculated laser damage limits of 0.3--2.3 J/cm{sup 2} of beam energy and neutron lifetime fluence limits of over 5 {times} 10{sup 20} 14 MeV n/cm{sup 2} when used at grazing incidence and operated at room temperature or at 77 K. A final focusing system including mirrors made of Al alloy 7475 at room temperature or at liquid nitrogen temperatures used with a driver which delivers 5 MJ of beam energy in 32 beams would require 32 mirrors of roughly 10 m{sup 2} each. This chapter includes calculations of damage limits for GIMMs and discusses critical issues relevant to the integrity and lifetime of such mirrors in a reactor environment. The reflectivities of various metals are calculated from measured optical constants at room temperature and at cryogenic temperatures for 250- to 500-nm light at both normal and grazing incidence. Then, for the mirrors in a representativemore » system, the thermal absorption and conduction rates of the best candidate metals are used with the maximum allowable cyclic thermal stress to give the maximum allowed surface-temperature rise and surface thermal load. The allowed surface thermal load and surface reflectivity give the maximum beam energy density and the minimum size for each mirror. For mirrors made of aluminum alloy 7475 and initially operated at room temperature, the resulting optical damage threshold and allowable temperature rise give a required mirror size for each final mirror. Critical issues relevant to the integrity and lifetime of such mirrors in a reactor environment are briefly discussed.« less

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
5182749
Report Number(s):
UCRL-ID-106094
ON: DE92000093
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; LASER FUSION REACTORS; LASER MIRRORS; PHYSICAL RADIATION EFFECTS; BEAM OPTICS; CRYOGENICS; DAMAGE; DAMAGING NEUTRON FLUENCE; DIELECTRIC MATERIALS; ICF DEVICES; METALS; NEUTRON TRANSPORT; REFLECTIVITY; SERVICE LIFE; TEMPERATURE EFFECTS; ELEMENTS; MATERIALS; MIRRORS; NEUTRAL-PARTICLE TRANSPORT; NEUTRON FLUENCE; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; RADIATION EFFECTS; RADIATION TRANSPORT; SURFACE PROPERTIES; THERMONUCLEAR DEVICES; THERMONUCLEAR REACTORS; 700208* - Fusion Power Plant Technology- Inertial Confinement Technology

Citation Formats

Bieri, R, and Guinan, M. An analysis of grazing incidence metal mirrors in a laser ICF reactor driver. United States: N. p., 1991. Web. doi:10.2172/5182749.
Bieri, R, & Guinan, M. An analysis of grazing incidence metal mirrors in a laser ICF reactor driver. United States. https://doi.org/10.2172/5182749
Bieri, R, and Guinan, M. 1991. "An analysis of grazing incidence metal mirrors in a laser ICF reactor driver". United States. https://doi.org/10.2172/5182749. https://www.osti.gov/servlets/purl/5182749.
@article{osti_5182749,
title = {An analysis of grazing incidence metal mirrors in a laser ICF reactor driver},
author = {Bieri, R and Guinan, M},
abstractNote = {Grazing incidence metal mirrors (GIMMs) are examined to replace dielectric mirrors for the final elements in a laser beam line for an inertial confinement fusion reactor. For a laser driver with a wavelength from 250 to 500 nm in a 10-ms pulse, irradiated mirrors made of Al, Al alloys, or Mg were found to have calculated laser damage limits of 0.3--2.3 J/cm{sup 2} of beam energy and neutron lifetime fluence limits of over 5 {times} 10{sup 20} 14 MeV n/cm{sup 2} when used at grazing incidence and operated at room temperature or at 77 K. A final focusing system including mirrors made of Al alloy 7475 at room temperature or at liquid nitrogen temperatures used with a driver which delivers 5 MJ of beam energy in 32 beams would require 32 mirrors of roughly 10 m{sup 2} each. This chapter includes calculations of damage limits for GIMMs and discusses critical issues relevant to the integrity and lifetime of such mirrors in a reactor environment. The reflectivities of various metals are calculated from measured optical constants at room temperature and at cryogenic temperatures for 250- to 500-nm light at both normal and grazing incidence. Then, for the mirrors in a representative system, the thermal absorption and conduction rates of the best candidate metals are used with the maximum allowable cyclic thermal stress to give the maximum allowed surface-temperature rise and surface thermal load. The allowed surface thermal load and surface reflectivity give the maximum beam energy density and the minimum size for each mirror. For mirrors made of aluminum alloy 7475 and initially operated at room temperature, the resulting optical damage threshold and allowable temperature rise give a required mirror size for each final mirror. Critical issues relevant to the integrity and lifetime of such mirrors in a reactor environment are briefly discussed.},
doi = {10.2172/5182749},
url = {https://www.osti.gov/biblio/5182749}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jul 12 00:00:00 EDT 1991},
month = {Fri Jul 12 00:00:00 EDT 1991}
}