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Title: The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers

Abstract

Nuclear-pumped lasers (NPLs) are driven by the products of nuclear reactions and directly convert the nuclear energy to directed optical energy. Pumping gas lasers by nuclear reaction products has the advantage of depositing large energies per reaction. The need for high laser power output implies high operating pressure. In the case of volumetric excitation by 3He(n, p)3H reactions, however, operation at high pressure (more than a few atm) causes excessive neutron attenuation in the 3He gas. This fact adversely effects on energy deposition and, hence, laser output power and beam quality. Here, spatial and temporal variations of neutron flux inside a closed 3He -filled cylindrical laser tube have been numerically calculated for various tube radii and operating pressures by using a previously reported dynamic model for energy deposition. Calculations are made by using ITU TRIGA Mark II Reactor as the neutron source. The effects of neutron attenuation on power deposition are examined.

Authors:
 [1]
  1. Istanbul Technical University, Energy Institute, Istanbul (Turkey)
Publication Date:
OSTI Identifier:
21057089
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 899; Journal Issue: 1; Conference: 6. international conference of the Balkan Physical Union, Istanbul (Turkey), 22-26 Aug 2006; Other Information: DOI: 10.1063/1.2733056; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ATTENUATION; ENERGY ABSORPTION; EXCITATION; GAS LASERS; HELIUM 3; HELIUM 3 TARGET; NEUTRON FLUX; NEUTRON REACTIONS; NEUTRON SOURCES; NEUTRONS; NUCLEAR PUMPING; NUMERICAL ANALYSIS; PROTON-NEUTRON INTERACTIONS; PROTONS; TRIGA-2 REACTOR; TRITONS

Citation Formats

Cetin, Fuesun. The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers. United States: N. p., 2007. Web. doi:10.1063/1.2733056.
Cetin, Fuesun. The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers. United States. doi:10.1063/1.2733056.
Cetin, Fuesun. Mon . "The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers". United States. doi:10.1063/1.2733056.
@article{osti_21057089,
title = {The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers},
author = {Cetin, Fuesun},
abstractNote = {Nuclear-pumped lasers (NPLs) are driven by the products of nuclear reactions and directly convert the nuclear energy to directed optical energy. Pumping gas lasers by nuclear reaction products has the advantage of depositing large energies per reaction. The need for high laser power output implies high operating pressure. In the case of volumetric excitation by 3He(n, p)3H reactions, however, operation at high pressure (more than a few atm) causes excessive neutron attenuation in the 3He gas. This fact adversely effects on energy deposition and, hence, laser output power and beam quality. Here, spatial and temporal variations of neutron flux inside a closed 3He -filled cylindrical laser tube have been numerically calculated for various tube radii and operating pressures by using a previously reported dynamic model for energy deposition. Calculations are made by using ITU TRIGA Mark II Reactor as the neutron source. The effects of neutron attenuation on power deposition are examined.},
doi = {10.1063/1.2733056},
journal = {AIP Conference Proceedings},
number = 1,
volume = 899,
place = {United States},
year = {Mon Apr 23 00:00:00 EDT 2007},
month = {Mon Apr 23 00:00:00 EDT 2007}
}
  • Ozone yield from the irradiation of O/sub 2/--SF/sub 6/ mixtures has been utilized for calibration of power deposition in boron-10 coated tubes used in nuclear pumped laser experiments. Laser experiments using such tubes have previously relied solely on theoretical calculations. Results obtained from an O/sub 2/--SF/sub 6/ dosimeter show reasonable agreement with recent theoretical calculations and, because of its simplicity and accuracy, the use of this dosimeter is proposed for calibration of nuclear pumped laser sources.
  • Pumping gas lasers by the /sup 235/U(n,ff)FF reaction has the advantage of depositing large energies per reaction (approx.200 MeV), and by using /sup 235/UF/sub 6/, a volumetric energy source is achieved. Factors in /sup 235/UF/sub 6/ pumping of a He gas relating to neutron attenuation and fission product transport within a laser tube are treated in detail. Neutron attenuation is found not to be significant for tube sizes and pressure ranges anticipated for laser applications. Maximum power can be deposited in a laser tube when the tube radius is at least as large as the range of the fission fragments.more » The maximum power is deposited in the helium gas when the tube radius equals the fission-fragment range and the UF/sub 6/ partial pressure to total pressure ratio is 0.15 corresponding to a UF/sub 6/-He mixing ratio of approximately 1 : 6.« less
  • An interference technique is developed for determining the energy deposition in gas-flow lasers pumped by uranium fission fragments. It is shown that four types of interference patterns may be formed. Algorithms are presented for determining the type of interference and for enumerating the maxima in interference pattern. (lasers, active media)
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  • The interaction of neutron beams with /sup 3/He gas is of interest for nuclear pumped lasers. The effects of spectral dependence of the neutron beam, neutron attenuation in the gas-filled laser tube, and transport of the charged-particle /sup 3/He(n,p)/sup 3/H reaction products are treated in detail. An expression for the energy density as a function of position within the tube, tube radius, operating pressure, and neutron fluence is given. The maximum energy density within the optical cavity is achieved when the tube radius a (cm) is given by a=3.26/P where P (atm) is the operating pressure. The variation of radiusmore » by 50% above and below optimum will change the energy density at most by 10%, although performance degrades quickly for radii outside this range. If the optimum tube radius is used for each operating pressure, then the power density on the centerline (kW/cm/sup 3/) is given as xi/sub CL/=9.3 x 10/sup -18/Pf/sub 0/ in a thermal neutron environment of f/sub 0/ (n/cm/sup 2/ sec).« less