Performance degradation of ferrofluidic feedthroughs in a mixed irradiation field

Journal Article · Thu Oct 06 00:00:00 EDT 2016 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

DOI:https://doi.org/10.1016/j.nima.2016.10.007· OSTI ID:1347294

Simos, Nikolaos ^[1]; Fernandes, S. ^[2]; Mittig, Wolfgang ^[3]; Pellemoine, Frederique ^[2]; Avilov, M. ^[2]; Kostin, M. ^[2]; Mausner, L. ^[1]; Ronningen, R. ^[2]; Schein, M. ^[2]; Bollen, G. ^[2]

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1. Brookhaven National Lab. (BNL), Upton, NY (United States)
2. Michigan State Univ., East Lansing, MI (United States). Facility for Rare Isotope Beams (FRIB)
3. Michigan State Univ., East Lansing, MI (United States). Facility for Rare Isotope Beams (FRIB) and National Superconducting Cyclotron Laboratory NSCL

We present ferrofluidic feedthrough (FF) rotary seals containing either NdFeB or SmCo-type permanent magnets that have been considered for use in the target and beam dump systems of the Facility for Rare Isotope Beams (FRIB). To evaluate their performance under irradiation three FF seals were irradiated in a mixed field consisting of fast neutrons, protons and γ-rays to an average absorbed dose of 0.2, 2.0, and 20.0 MGy at the Brookhaven Linac Isotope Producer facility (BLIP). The radiation types and energy profiles mimic those expected at the FRIB facility. Degradation of the operational performance of these devices due to irradiation is expected to be the result of the de-magnetization of the permanent magnets contained within the seal and the changes in the ferrofluid properties. Post-irradiation performance was evaluated by determining the ferrofluidic seal vacuum tightness and torque under static and dynamic conditions. The study revealed that the ferrofluidic feedthrough seal irradiated to a dose of 0.2 MGy maintained its vacuum tightness under both static and rotational condition while the one irradiated to a dose of 2.0 MGy exhibited signs of ferrofluid damage but no overall performance loss. Lastly, at 20 MGy dose the effects of irradiation on the ferrofluid properties (viscosity and particle agglomeration) were shown to be severe. Furthermore, limited de-magnetization of the annular shaped Nd₂Fe₁₄B and Sm₂Co₁₇ magnets located within the irradiated FFs was observed for doses of 0.2 MGy and 20 MGy respectively.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: SC00112704; SC0000661
• OSTI ID: 1347294
• Alternate ID(s): OSTI ID: 1397766
• Report Number(s): BNL-113600-2017-JA; TRN: US1701565
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 841; ISSN 0168-9002
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Neutron irradiation
De-magnetization
Radiation damage
Ferrofluidic feedthrough
Performance
Static torque
Rotational torque
Leak rate