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Title: Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility

Abstract

DT neutron yield (Y{sub n}), ion temperature (T{sub i}) and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-Time-Of-Flight (nTOF) spectrometers and a Magnetic Recoil Spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the redundancy required for reliable measurements of Yn, Ti and dsr. From the measured dsr value, an areal density ({rho}R) is determined from the relationship {rho}R{sub tot} (g/cm{sup 2}) = (20.4 {+-} 0.6) x dsr{sub 10-12 MeV}. The proportionality constant is determined considering implosion geometry, neutron attenuation and energy range used for the dsr measurement. To ensure high accuracy in the measurements, a series of commissioning experiments using exploding pushers have been used for in situ calibration. The spectrometers are now performing to the required accuracy, as indicated by the good agreement between the different measurements over several commissioning shots. In addition, recent data obtained with the MRS and nTOFs indicate that the implosion performance of cryogenically layered DT implosions, characterized by the experimental Ignition Threshold Factor (ITFx) which is a function of dsr (ormore » fuel {rho}R) and Y{sub n}, has improved almost two orders of magnitude since the first shot in September, 2010.« less

Authors:
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Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1043648
Report Number(s):
LLNL-CONF-555952
TRN: US1203169
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 19th Topical Conference High-Temperature Plasma Diagnostics, Monterey, CA, United States, May 06 - May 10, 2012
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 42 ENGINEERING; ACCURACY; ATTENUATION; CALIBRATION; COMMISSIONING; ENERGY RANGE; GEOMETRY; IGNITION; IMPLOSIONS; INERTIAL CONFINEMENT; ION TEMPERATURE; METRICS; NEUTRON SPECTRA; NEUTRON SPECTROSCOPY; NEUTRONS; PERFORMANCE; PLASMA DIAGNOSTICS; REDUNDANCY; SPECTROMETERS; TARGET CHAMBERS; US NATIONAL IGNITION FACILITY

Citation Formats

Mackinnon, A J, Johnson, M G, Frenje, J A, Casey, D T, Li, C K, Seguin, F H, Petrasso, R, Ashabranner, R, Cerjan, C, Clancy, T J, Bionta, R, Bleuel, D, Bond, E J, Caggiano, J A, Capenter, A, Eckart, M J, Edwards, M J, Friedrich, S, Glenzer, S H, Haan, S W, Hartouni, E P, Hatarik, R, Hachett, S P, McKernan, M, Jones, O, Lepape, S, Lerche, R A, Landen, O L, Moran, M, Moses, E, Munro, D, McNaney, J, Rygg, J R, Sepke, S, Spears, B, Springer, P, Yeamans, C, Farrell, M, Kilkenny, J D, Nikroo, A, Paguio, R, Knauer, J, Glebov, V, Sangster, T, Betti, R, Stoeckl, C, Magoon, J, Shoup, M J, Grim, G P, Moran, G L, Murphy, T J, Leeper, R J, and Ruiz, C. Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility. United States: N. p., 2012. Web.
Mackinnon, A J, Johnson, M G, Frenje, J A, Casey, D T, Li, C K, Seguin, F H, Petrasso, R, Ashabranner, R, Cerjan, C, Clancy, T J, Bionta, R, Bleuel, D, Bond, E J, Caggiano, J A, Capenter, A, Eckart, M J, Edwards, M J, Friedrich, S, Glenzer, S H, Haan, S W, Hartouni, E P, Hatarik, R, Hachett, S P, McKernan, M, Jones, O, Lepape, S, Lerche, R A, Landen, O L, Moran, M, Moses, E, Munro, D, McNaney, J, Rygg, J R, Sepke, S, Spears, B, Springer, P, Yeamans, C, Farrell, M, Kilkenny, J D, Nikroo, A, Paguio, R, Knauer, J, Glebov, V, Sangster, T, Betti, R, Stoeckl, C, Magoon, J, Shoup, M J, Grim, G P, Moran, G L, Murphy, T J, Leeper, R J, & Ruiz, C. Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility. United States.
Mackinnon, A J, Johnson, M G, Frenje, J A, Casey, D T, Li, C K, Seguin, F H, Petrasso, R, Ashabranner, R, Cerjan, C, Clancy, T J, Bionta, R, Bleuel, D, Bond, E J, Caggiano, J A, Capenter, A, Eckart, M J, Edwards, M J, Friedrich, S, Glenzer, S H, Haan, S W, Hartouni, E P, Hatarik, R, Hachett, S P, McKernan, M, Jones, O, Lepape, S, Lerche, R A, Landen, O L, Moran, M, Moses, E, Munro, D, McNaney, J, Rygg, J R, Sepke, S, Spears, B, Springer, P, Yeamans, C, Farrell, M, Kilkenny, J D, Nikroo, A, Paguio, R, Knauer, J, Glebov, V, Sangster, T, Betti, R, Stoeckl, C, Magoon, J, Shoup, M J, Grim, G P, Moran, G L, Murphy, T J, Leeper, R J, and Ruiz, C. 2012. "Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility". United States. https://www.osti.gov/servlets/purl/1043648.
@article{osti_1043648,
title = {Neutron spectrometry - An essential tool for diagnosing implosions at the National Ignition Facility},
author = {Mackinnon, A J and Johnson, M G and Frenje, J A and Casey, D T and Li, C K and Seguin, F H and Petrasso, R and Ashabranner, R and Cerjan, C and Clancy, T J and Bionta, R and Bleuel, D and Bond, E J and Caggiano, J A and Capenter, A and Eckart, M J and Edwards, M J and Friedrich, S and Glenzer, S H and Haan, S W and Hartouni, E P and Hatarik, R and Hachett, S P and McKernan, M and Jones, O and Lepape, S and Lerche, R A and Landen, O L and Moran, M and Moses, E and Munro, D and McNaney, J and Rygg, J R and Sepke, S and Spears, B and Springer, P and Yeamans, C and Farrell, M and Kilkenny, J D and Nikroo, A and Paguio, R and Knauer, J and Glebov, V and Sangster, T and Betti, R and Stoeckl, C and Magoon, J and Shoup, M J and Grim, G P and Moran, G L and Murphy, T J and Leeper, R J and Ruiz, C},
abstractNote = {DT neutron yield (Y{sub n}), ion temperature (T{sub i}) and down-scatter ratio (dsr) determined from measured neutron spectra are essential metrics for diagnosing the performance of Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). A suite of neutron-Time-Of-Flight (nTOF) spectrometers and a Magnetic Recoil Spectrometer (MRS) have been implemented in different locations around the NIF target chamber, providing good implosion coverage and the redundancy required for reliable measurements of Yn, Ti and dsr. From the measured dsr value, an areal density ({rho}R) is determined from the relationship {rho}R{sub tot} (g/cm{sup 2}) = (20.4 {+-} 0.6) x dsr{sub 10-12 MeV}. The proportionality constant is determined considering implosion geometry, neutron attenuation and energy range used for the dsr measurement. To ensure high accuracy in the measurements, a series of commissioning experiments using exploding pushers have been used for in situ calibration. The spectrometers are now performing to the required accuracy, as indicated by the good agreement between the different measurements over several commissioning shots. In addition, recent data obtained with the MRS and nTOFs indicate that the implosion performance of cryogenically layered DT implosions, characterized by the experimental Ignition Threshold Factor (ITFx) which is a function of dsr (or fuel {rho}R) and Y{sub n}, has improved almost two orders of magnitude since the first shot in September, 2010.},
doi = {},
url = {https://www.osti.gov/biblio/1043648}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed May 02 00:00:00 EDT 2012},
month = {Wed May 02 00:00:00 EDT 2012}
}

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