Errors in the field reconstruction using CR-39 proton radiographs with high fluence variation
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103527_1_5.0219510.pdf
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Published version
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4.52 MB
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Checksum (MD5)
f3d4f3411e0c71106cacb89900271ed2
Author(s)
Foo, BC
Buschmann, BI
Cufari, M
Dannhoff, SG
DeVault, A
Evans, TE
Johnson, TM
Kunimune, JH
Lawrence, Y
Pearcy, JA
Date Issued
October 31, 2024
Journal
Review of Scientific Instruments
Publisher
AIP Publishing
Citation
B. C. Foo, B. I. Buschmann, M. Cufari, S. G. Dannhoff, A. DeVault, T. E. Evans, T. M. Johnson, J. H. Kunimune, Y. Lawrence, J. A. Pearcy, B. L. Reichelt, L. Russell, N. Vanderloo, J. Vargas, C. W. Wink, M. Gatu Johnson, F. H. Séguin, R. D. Petrasso, J. A. Frenje; Errors in the field reconstruction using CR-39 proton radiographs with high fluence variation. Rev. Sci. Instrum. 1 October 2024; 95 (10): 103527.
Version
Final published version
Abstract
CR-39 proton radiography is an experimental charged-particle backlighter platform fielded and used at OMEGA and the NIF to image electric and magnetic fields in a subject plasma. Processing a piece of CR-39 involves etching it in hot NaOH, and the etch time can greatly impact the background-to-signal ratio (BSR) in low-fluence (≲4 × 104 cm−2) regions and detection efficiency in high-fluence regions (≳7 × 105 cm−2). For CR-39 data with high fluence variation, these effects mean that any single etch time will result in ≳15% error in the measured signal in either the high- or low-fluence regions. This study aims to quantify the impact of the etch time on the BSR and efficiency losses and how these affect the field reconstruction. Experiments at the MIT Linear Electrostatic Ion Accelerator provided empirical values of the BSR and efficiency losses as a function of the fluence and etch time for fluences ranging from 3 × 103 to 7 × 105 cm−2. Synthetic radiographs were generated with known fields and modulated based on empirical values of BSR and efficiency losses. The fields were reconstructed using a Monge–Ampère code with the modulated radiographs as input. The results indicate that combining short and long etches allows for more accurate analysis of radiographs with high fluence variation, with the mean squared error of the reconstructed fields decreasing by factors of 1.2–7 compared to the reconstructions using only one etch time.
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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DOI of Published Version
https://doi.org/10.1063/5.0219510
