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Title: (U) An Analytic Examination of Piezoelectric Ejecta Mass Measurements

Abstract

Ongoing efforts to validate a Richtmyer-Meshkov instability (RMI) based ejecta source model [1, 2, 3] in LANL ASC codes use ejecta areal masses derived from piezoelectric sensor data [4, 5, 6]. However, the standard technique for inferring masses from sensor voltages implicitly assumes instantaneous ejecta creation [7], which is not a feature of the RMI source model. To investigate the impact of this discrepancy, we define separate “areal mass functions” (AMFs) at the source and sensor in terms of typically unknown distribution functions for the ejecta particles, and derive an analytic relationship between them. Then, for the case of single-shock ejection into vacuum, we use the AMFs to compare the analytic (or “true”) accumulated mass at the sensor with the value that would be inferred from piezoelectric voltage measurements. We confirm the inferred mass is correct when creation is instantaneous, and furthermore prove that when creation is not instantaneous, the inferred values will always overestimate the true mass. Finally, we derive an upper bound for the error imposed on a perfect system by the assumption of instantaneous ejecta creation. When applied to shots in the published literature, this bound is frequently less than several percent. Errors exceeding 15% may requiremore » velocities or timescales at odds with experimental observations.« less

Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1342849
Report Number(s):
LA-UR-17-20814
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Tregillis, Ian Lee. (U) An Analytic Examination of Piezoelectric Ejecta Mass Measurements. United States: N. p., 2017. Web. doi:10.2172/1342849.
Tregillis, Ian Lee. (U) An Analytic Examination of Piezoelectric Ejecta Mass Measurements. United States. doi:10.2172/1342849.
Tregillis, Ian Lee. Thu . "(U) An Analytic Examination of Piezoelectric Ejecta Mass Measurements". United States. doi:10.2172/1342849. https://www.osti.gov/servlets/purl/1342849.
@article{osti_1342849,
title = {(U) An Analytic Examination of Piezoelectric Ejecta Mass Measurements},
author = {Tregillis, Ian Lee},
abstractNote = {Ongoing efforts to validate a Richtmyer-Meshkov instability (RMI) based ejecta source model [1, 2, 3] in LANL ASC codes use ejecta areal masses derived from piezoelectric sensor data [4, 5, 6]. However, the standard technique for inferring masses from sensor voltages implicitly assumes instantaneous ejecta creation [7], which is not a feature of the RMI source model. To investigate the impact of this discrepancy, we define separate “areal mass functions” (AMFs) at the source and sensor in terms of typically unknown distribution functions for the ejecta particles, and derive an analytic relationship between them. Then, for the case of single-shock ejection into vacuum, we use the AMFs to compare the analytic (or “true”) accumulated mass at the sensor with the value that would be inferred from piezoelectric voltage measurements. We confirm the inferred mass is correct when creation is instantaneous, and furthermore prove that when creation is not instantaneous, the inferred values will always overestimate the true mass. Finally, we derive an upper bound for the error imposed on a perfect system by the assumption of instantaneous ejecta creation. When applied to shots in the published literature, this bound is frequently less than several percent. Errors exceeding 15% may require velocities or timescales at odds with experimental observations.},
doi = {10.2172/1342849},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 02 00:00:00 EST 2017},
month = {Thu Feb 02 00:00:00 EST 2017}
}

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