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Title: Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 90-degree Off-axis Parabolic Mirrors

Abstract

Gas Cherenkov detectors (GCD) have been used to convert fusion gamma into photons to achieve gamma bang time (GBT) and reaction history measurements. The GCD designed for Omega used Cassegrain reflector optics in order to fit inside a 10-inch manipulator. A novel design for the National Ignition Facility (NIF) using 90º off-axis parabolic (OAP) mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO2 gas volume, the detector is positioned at the stop position rather than an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100-mm-diameter by 500-mm-long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO2 gas volume. A cluster of four channels will allow for increased dynamic range, as well as different gamma energy threshold sensitivities.

Authors:
Publication Date:
Research Org.:
National Security Technologies, LLC (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NA)
OSTI Identifier:
960420
Report Number(s):
DOE/NV/25946-513
Journal ID: ISSN 0034-6748; RSINAK; TRN: US0903146
DOE Contract Number:  
DE-AC52-06NA25946
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 79; Journal Issue: 10; Journal ID: ISSN 0034-6748
Publisher:
Review of Scientific Instruments
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CHERENKOV COUNTERS; DESIGN; EFFICIENCY; ELECTRONS; MIRRORS; OPTICS; PHOTONS; TRAJECTORIES; US NATIONAL IGNITION FACILITY; off-axis parabolic mirror, gamma bang time, reaction history

Citation Formats

R.M. Malone, H.W. Herrmann, J.M. Mack, C.S. Young, W. Stoeffl. Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 90-degree Off-axis Parabolic Mirrors. United States: N. p., 2008. Web. doi:10.1063/1.2969281.
R.M. Malone, H.W. Herrmann, J.M. Mack, C.S. Young, W. Stoeffl. Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 90-degree Off-axis Parabolic Mirrors. United States. doi:10.1063/1.2969281.
R.M. Malone, H.W. Herrmann, J.M. Mack, C.S. Young, W. Stoeffl. Wed . "Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 90-degree Off-axis Parabolic Mirrors". United States. doi:10.1063/1.2969281.
@article{osti_960420,
title = {Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 90-degree Off-axis Parabolic Mirrors},
author = {R.M. Malone, H.W. Herrmann, J.M. Mack, C.S. Young, W. Stoeffl},
abstractNote = {Gas Cherenkov detectors (GCD) have been used to convert fusion gamma into photons to achieve gamma bang time (GBT) and reaction history measurements. The GCD designed for Omega used Cassegrain reflector optics in order to fit inside a 10-inch manipulator. A novel design for the National Ignition Facility (NIF) using 90º off-axis parabolic (OAP) mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO2 gas volume, the detector is positioned at the stop position rather than an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100-mm-diameter by 500-mm-long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO2 gas volume. A cluster of four channels will allow for increased dynamic range, as well as different gamma energy threshold sensitivities.},
doi = {10.1063/1.2969281},
journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 10,
volume = 79,
place = {United States},
year = {2008},
month = {10}
}