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Song J, Zheng J, Chen Z, Chen J, Wang F. Neutron penumbral image reconstruction with a convolution neural network using fast Fourier transform. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:013509. [PMID: 38265276 DOI: 10.1063/5.0175347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 12/30/2023] [Indexed: 01/25/2024]
Abstract
In Inertial Confinement Fusion (ICF), the asymmetry of a hot spot is an important influence factor in implosion performance. Neutron penumbral imaging, which serves as an encoded-aperture imaging technique, is one of the most important diagnostic methods for detecting the shape of a hot spot. The detector image is a uniformly bright range surrounded by a penumbral area, which presents the strength distribution of hot spots. The present diagnostic modality employs an indirect imaging technique, necessitating the reconstruction process to be a pivotal aspect of the imaging protocol. The accuracy of imaging and the applicable range are significantly influenced by the reconstruction algorithm employed. We develop a neural network named Fast Fourier transform Neural Network (FFTNN) to reconstruct two-dimensional neutron emission images from the penumbral area of the detector images. The FFTNN architecture consists of 16 layers that include a FFT layer, convolution layer, fully connected layer, dropout layer, and reshape layer. Due to the limitations in experimental data, we propose a phenomenological method for describing hot spots to generate datasets for training neural networks. The reconstruction performance of the trained FFTNN is better than that of the traditional Wiener filtering and Lucy-Richardson algorithm on the simulated dataset, especially when the noise level is high as indicated by the evaluation metrics, such as mean squared error and structure similar index measure. This proposed neural network provides a new perspective, paving the way for integrating neutron imaging diagnosis into ICF.
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Affiliation(s)
- Jianjun Song
- Laser Fusion Reacher Center, China Academic of Engineering Physics, Mianyang, SiChuan 621900, China
| | - Jianhua Zheng
- Laser Fusion Reacher Center, China Academic of Engineering Physics, Mianyang, SiChuan 621900, China
| | - Zhongjing Chen
- Laser Fusion Reacher Center, China Academic of Engineering Physics, Mianyang, SiChuan 621900, China
| | - Jihui Chen
- Laser Fusion Reacher Center, China Academic of Engineering Physics, Mianyang, SiChuan 621900, China
| | - Feng Wang
- Laser Fusion Reacher Center, China Academic of Engineering Physics, Mianyang, SiChuan 621900, China
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Fittinghoff DN, Birge N, Geppert-Kleinrath V. Neutron imaging of inertial confinement fusion implosions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:021101. [PMID: 36859056 DOI: 10.1063/5.0124074] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 01/07/2023] [Indexed: 06/18/2023]
Abstract
We review experimental neutron imaging of inertial confinement fusion sources, including the neutron imaging systems that have been used in our measurements at the National Ignition Facility. These systems allow measurements with 10 µm resolution for fusion deuterium-deuterium and deuterium-tritium neutron sources with mean radius up to 400 µm, including measurements of neutrons scattered to lower energy in the remaining cold fuel. These measurements are critical for understanding the fusion burn volume and the three-dimensional effects that can reduce the neutron yields.
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Affiliation(s)
- D N Fittinghoff
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N Birge
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Zhang C, Cao L, Dai Y, Li D, Yu J, Yan M, Deng J, Wang X, Zhou C, Ruan S. Simulation of a micron resolution capillary liquid scintillation detector for 14 MeV fusion neutrons. Appl Radiat Isot 2022; 189:110424. [DOI: 10.1016/j.apradiso.2022.110424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 08/06/2022] [Accepted: 08/13/2022] [Indexed: 11/02/2022]
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Lamb KM, Geppert-Kleinrath V, Birge NW, Danly CR, Divol L, Fittinghoff DN, Freeman MS, Pak AE, Wilde CH, Zylstra AB, Volegov PL. Bootstrap estimation of the effect of instrument response function uncertainty on the reconstruction of fusion neutron sources. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:043508. [PMID: 35489948 DOI: 10.1063/5.0086450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
Neutron imagers are important diagnostics for the inertial confinement fusion implosions at the National Ignition Facility. They provide two- and three-dimensional reconstructions of the neutron source shape that are key indicators of the overall performance. To interpret the shape results properly, it is critical to estimate the uncertainty in those reconstructions. There are two main sources of uncertainties: limited neutron statistics, leading to random errors in the reconstructed images, and incomplete knowledge of the instrument response function (the pinhole-dependent point spread function). While the statistical errors dominate the uncertainty for lower yield deuterium-tritium (DT) shots, errors due to the instrument response function dominate the uncertainty for DT yields on the order of 1016 neutrons or higher. In this work, a bootstrapping method estimates the uncertainty in a reconstructed image due to the incomplete knowledge of the instrument response function. The main reconstruction is created from the fixed collection of pinhole images that are best aligned with the neutron source. Additional reconstructions are then built using subsets of that collection of images. Variations in the shapes of these additional reconstructions originate solely from uncertainties in the instrument response function, allowing us to use them to provide an additional systematic uncertainty estimate.
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Affiliation(s)
- Kevin M Lamb
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | | | - Noah W Birge
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | | | - Laurent Divol
- Lawrence-Livermore National Laboratory, Livermore, California 94550, USA
| | | | | | - Arthur E Pak
- Lawrence-Livermore National Laboratory, Livermore, California 94550, USA
| | - Carl H Wilde
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Alex B Zylstra
- Lawrence-Livermore National Laboratory, Livermore, California 94550, USA
| | - Petr L Volegov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
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Volegov PL, Batha SH, Fittinghoff DN, Danly CR, Geppert-Kleinrath V, Wilde CH, Zylstra AB. Three-dimensional reconstruction of neutron, gamma-ray, and x-ray sources using a cylindrical-harmonics expansion. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033508. [PMID: 33820056 DOI: 10.1063/5.0042860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
Inertial confinement fusion capsule implosions produce neutron, gamma-ray, and x-ray emission, which are recorded by a variety of detectors, both time integrated and time resolved, to determine the performance of the implosion. Two-dimensional emission images from multiple directions can now be combined to infer three-dimensional structures in the implosion, such as the distribution of thermonuclear fuel density, carbon ablator, and impurities. Because of the cost and complexity of the imaging systems, however, only a few measurements can be made, so reconstructions of the source must be made from a limited number of views. Here, a cylindrical-harmonics decomposition technique to reconstruct the three-dimensional object from two views in the same symmetry plane is presented. In the limit of zero order, this method recovers the Abel inversion method. The detailed algorithms used for this characterization and the resulting reconstructed neutron source from an experiment collected at the National Ignition Facility are presented.
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Affiliation(s)
- P L Volegov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - S H Batha
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - D N Fittinghoff
- Livermore National Laboratory, Livermore, California 94550, USA
| | - C R Danly
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | | | - C H Wilde
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - A B Zylstra
- Livermore National Laboratory, Livermore, California 94550, USA
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Danly CR, Christensen K, Fatherley VE, Fittinghoff DN, Grim GP, Hibbard R, Izumi N, Jedlovec D, Merrill FE, Schmidt DW, Simpson RA, Skulina K, Volegov PL, Wilde CH. Combined neutron and x-ray imaging at the National Ignition Facility (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11D703. [PMID: 27910487 DOI: 10.1063/1.4962194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
X-ray and neutrons are commonly used to image inertial confinement fusion implosions, providing key diagnostic information on the fuel assembly of burning deuterium-tritium (DT) fuel. The x-ray and neutron data provided are complementary as the production of neutrons and x-rays occurs from different physical processes, but typically these two images are collected from different views with no opportunity for co-registration of the two images. Neutrons are produced where the DT fusion fuel is burning; X-rays are produced in regions corresponding to high temperatures. Processes such as mix of ablator material into the hotspot can result in increased x-ray production and decreased neutron production but can only be confidently observed if the two images are collected along the same line of sight and co-registered. To allow direct comparison of x-ray and neutron data, a combined neutron x-ray imaging system has been tested at Omega and installed at the National Ignition Facility to collect an x-ray image along the currently installed neutron imaging line of sight. This system is described, and initial results are presented along with prospects for definitive coregistration of the images.
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Affiliation(s)
- C R Danly
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - K Christensen
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - V E Fatherley
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - D N Fittinghoff
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G P Grim
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - R Hibbard
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N Izumi
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D Jedlovec
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - F E Merrill
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - D W Schmidt
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - R A Simpson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - K Skulina
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - P L Volegov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - C H Wilde
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
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Zhang FN, Hu HS, Zhang TK, Jia QG, Wang DM, Jia J. A novel approach to correct the coded aperture misalignment for fast neutron imaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:123515. [PMID: 26724035 DOI: 10.1063/1.4939034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, "residual watermark," certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used to determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 μm. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.
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Affiliation(s)
- F N Zhang
- School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - H S Hu
- School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - T K Zhang
- Laser Fusion Research Center, CAEP, Mianyang, 621900 Sichuan, China
| | - Q G Jia
- Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
| | - D M Wang
- School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - J Jia
- School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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Danly CR, Day TH, Fittinghoff DN, Herrmann H, Izumi N, Kim YH, Martinez JI, Merrill FE, Schmidt DW, Simpson RA, Volegov PL, Wilde CH. Simultaneous neutron and x-ray imaging of inertial confinement fusion experiments along a single line of sight at Omega. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:043503. [PMID: 25933858 DOI: 10.1063/1.4918285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/04/2015] [Indexed: 06/04/2023]
Abstract
Neutron and x-ray imaging provide critical information about the geometry and hydrodynamics of inertial confinement fusion implosions. However, existing diagnostics at Omega and the National Ignition Facility (NIF) cannot produce images in both neutrons and x-rays along the same line of sight. This leads to difficulty comparing these images, which capture different parts of the plasma geometry, for the asymmetric implosions seen in present experiments. Further, even when opposing port neutron and x-ray images are available, they use different detectors and cannot provide positive information about the relative positions of the neutron and x-ray sources. A technique has been demonstrated on implosions at Omega that can capture x-ray images along the same line of sight as the neutron images. The technique is described, and data from a set of experiments are presented, along with a discussion of techniques for coregistration of the various images. It is concluded that the technique is viable and could provide valuable information if implemented on NIF in the near future.
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Affiliation(s)
- C R Danly
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - T H Day
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - D N Fittinghoff
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - H Herrmann
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - N Izumi
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Y H Kim
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - J I Martinez
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - F E Merrill
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - D W Schmidt
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - R A Simpson
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - P L Volegov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - C H Wilde
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
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