Title: Upgraded fiber-optic sensor system for dynamic strain measurement in Spallation Neutron Source

Abstract

We describe an upgraded fiber-optic sensor system and its performance in measuring the dynamic strains in a mercury target of the Spallation Neutron Source (SNS). Strains result from dynamic pressure waves in the stainless-steel mercury target induced by short (~700 ns), intense (up to 23.3 kJ), high-energy (~1 GeV) proton pulses. In the upgraded sensor system, the output of each sensor head is interrogated with a compact, all-fiber based Faraday Michelson interferometer, which generates interference signals with a steady phase shift. Strain waveforms are recovered from the phase-shifted interference signals using a high-speed digital signal processing procedure developed in our previous work. We demonstrate successful measurements of dynamic strain pulses, e.g., 400με over 190μs , on a recently installed SNS target using the upgraded sensor system. The measured strain waveforms are analyzed for more than 20 sensor locations and/or orientations, and provide information regarding the temporal structure of strain profiles and dependence of the strain magnitude on the proton powers of 200 – 1400 kW. The new interrogator also measures the radiation-induced-attenuation (RIA) in the optical fiber, enabling experimental investigations of RIA profiles induced by a 700-ns radiation pulse. The radiation effects on the strain measurement performance are discussed overmore » a radiation dose range of up to 4×10⁸ Gy and an RIA compensation method is proposed. The measurements allow insight into the response of this unique piece of equipment and can be used for validation of simulations.« less

Authors:

Liu, Yun  ^[1];

• Search DOE PAGES for author "Liu, Yun"
• Search DOE PAGES for ORCID "0000-0001-9843-2757"

Winder, Drew E.  ^[1];

• Search DOE PAGES for author "Winder, Drew E."
• Search DOE PAGES for ORCID "0000-0003-4045-7382"

Qi, Bing  ^[1];

• Search DOE PAGES for author "Qi, Bing"
• Search DOE PAGES for ORCID "0000-0001-7723-8998"

Long, Cary  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2506-4564"

Lu, Wei ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Sun Oct 24 00:00:00 EDT 2021

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1836445

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

IEEE Sensors Journal

Additional Journal Information:

Journal Volume: 21; Journal Issue: 23; Journal ID: ISSN 1530-437X

Publisher:

IEEE

Country of Publication:

United States

Language:

English

Subject:

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