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Title: Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

Abstract

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad. In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets alsomore » showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

Authors:
ORCiD logo [1];  [1];  [2]; ORCiD logo [3];  [3];  [3]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  3. Michigan State Univ., East Lansing, MI (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1454811
Report Number(s):
BNL-205752-2018-JAAM
Journal ID: ISSN 0018-9464; TRN: US1901153
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
IEEE Transactions on Magnetics
Additional Journal Information:
Journal Volume: 54; Journal Issue: 5; Journal ID: ISSN 0018-9464
Publisher:
Institute of Electrical and Electronics Engineers. Magnetics Group
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; irradiation-induced demagnetization; permanent magnets; radiation damage

Citation Formats

Simos, Nikolaos, Ozaki, S., Mokhov, N., Zeller, A., Mittig, W., and Pellemoine, F. Demagnetization of Nd2Fe14B, Pr2Fe14B, and Sm2Co17 Permanent Magnets in Spallation Irradiation Fields. United States: N. p., 2018. Web. doi:10.1109/TMAG.2017.2769040.
Simos, Nikolaos, Ozaki, S., Mokhov, N., Zeller, A., Mittig, W., & Pellemoine, F. Demagnetization of Nd2Fe14B, Pr2Fe14B, and Sm2Co17 Permanent Magnets in Spallation Irradiation Fields. United States. doi:10.1109/TMAG.2017.2769040.
Simos, Nikolaos, Ozaki, S., Mokhov, N., Zeller, A., Mittig, W., and Pellemoine, F. Tue . "Demagnetization of Nd2Fe14B, Pr2Fe14B, and Sm2Co17 Permanent Magnets in Spallation Irradiation Fields". United States. doi:10.1109/TMAG.2017.2769040. https://www.osti.gov/servlets/purl/1454811.
@article{osti_1454811,
title = {Demagnetization of Nd2Fe14B, Pr2Fe14B, and Sm2Co17 Permanent Magnets in Spallation Irradiation Fields},
author = {Simos, Nikolaos and Ozaki, S. and Mokhov, N. and Zeller, A. and Mittig, W. and Pellemoine, F.},
abstractNote = {Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd2Fe14B and Pr2Fe14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd2Fe14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr2Fe14B magnets irradiated to a lower dose of 20 Mrad. In addition, annular Sm2Co17 and Nd2Fe14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm2Co17 and 20 Mrad for Nd2Fe14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd2Fe14B magnets after only 50 Mrad dose and over 87% for Pr2Fe14B after 10 Mrad dose. The annular-shaped Sm2Co17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd2Fe14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.},
doi = {10.1109/TMAG.2017.2769040},
journal = {IEEE Transactions on Magnetics},
number = 5,
volume = 54,
place = {United States},
year = {2018},
month = {2}
}

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