Ion irradiation for nuclear materials research at University

Ion irradiation for nuclear materials research at University of Wisconsin. Madison Li He, Gabriel Meric De Bellefon, Kim Kriewaldt, Kumar Sridharan, Adrien Couet, Todd Allen University of Wisconsin – Madison SNEAP 2018 conference Madison, WI September 24 th, 2018 1

Overview • Ion Beam Lab and post-irradiation examination facility • Upgrades • Materials study examples • Access IBL 2

Ion Beam Laboratory (IBL) Irradiation Facility § 1. 7 MV tandem accelerator from National Electrostatics Corporation (NEC) § Temperature monitored with thermocouples and IR camera § Various samples geometries § Rastered or defocused beam § Toroidal Volume Ion Source (TORVIS) and Source of Negative Ions via Cesium Sputtering (SNICS) ion sources 3

Ion sources TORVIS q q High current hydrogen, deuterium, and helium ion source, from < 1 μA to 100 μA for protons (H+ ions). Emulate neutron irradiation effect with proton irradiation. Damage rate ~ 10 -6 dpa/s (displacements per atoms/s) Flat damage/depth profile. SNICS q q Wide range of heavy ions, Fe, Si, C, V, Nd, and more. Fast to achieve high damage, e. g. , 250 dpa peak damage of stainless steels in 9 hours. Damage rate 10 -4 -10 -2 dpa/s No radiation-induced radioactivity. 4

CLIM - PIE Equipment § JEOL 6610 SEM with Energy Dispersive Spectroscopy (EDS) and Electron Backscatter Diffraction (EBSD) capabilities § Rad sample certified (outside of CLIM): X-ray Diffraction. 5

CLIM - PIE Sample Preparation Facilities § Parallel polisher § Low speed saw § Electro-polisher § Ion mill § High accuracy balance 6

Non-rad sample PIE Materials Science Center at UW FEI Helios G 4 UX Plasma FIB/FE SEM FEI Titan Cs-corrected scanning transmission electron microscope Hysitron TI 950 Tribo. Indenter 7

Lab upgrade timeline • 2009: Nuclear Science User Facility partner. • 2011: TORVIS ion source (high beam current for H and He). • 2014: CLIM laboratory (consolidation of sample preparation tools and SEM). • 2015: Chamber upgrade (control of irradiation area, preloading chamber). • 2016: Sample activity screening (count integration over time, better accuracy). • 2017: Sample stage upgrade (liquid metal contact to ensure proper cooling). • 2018: two-dimensional moving sample stage. 8

Irradiation Chambers Parameter Chamber II (new)* 350°C - 1000°C -150°C - 1100°C 50°C - 800°C -150°C - 1000°C ± 10°C ± 5°C 2 thermocouples + IR camera 3 thermocouples + IR camera Flux Range, Protons 5 e 12 - 2 e 14 1 e 11 - 2 e 15 Flux Range, Heavy Ions 3 e 12 - 4 e 13 4 e 10 - 6 e 14 Irradiation Area Range 1. 5 – 4 cm 2 0. 1 – 6 cm 2 4 e-7 Torr 5 e-8 Torr No RBS, NRA, PIXE Temp Range: Protons Temp Range: Heavy Ions Temp Fluctuations Temp. control Vacuum In-situ analysis * Manufacturer specifications. 9

New Chamber Design § § Remote controlled four jaw slits for in-situ control of irradiation area Sample load-lock (pre-chamber) Liquid nitrogen cooling Tantalum wire heating elements on boron nitride mandrel, heating to 900ºC (radiative heating) § Handle both small and high current measurements (>3μA) – isolated (floating) stage § Openings for two low energy (<30 ke. V) ion guns 10

Indium cooling Stage Courtesy of Zefeng Yu • Provide accurate sample temperature measurements in accordance with ASTM E 521 guidelines. • In-situ temperature measurements by IR camera calibrated by thermocouples. • Efficient cooling by liquid indium pool (melting point 156. 6 ºC) for proton irradiation. 1 cm Indium pool at the center. 11

2 D-Moving stage Courtesy of Michael Moorehead • Stage is attached to 1 D-manipulator both vertically (automated) and horizontally (manual). • A ~ 2” × 3” area can be sequentially irradiated. 12

Rastering or defocused beam irradiation • Rastering beam achieves large irradiation area. However, beam lands on sample intermittently. • It has been reported that rastering beam may enhance interstitial/vacancy recombination, hinder void or other defect formation [1, 2]. Aperture confining irradiation area Zero flux High flux >> average flux Rastering beam Constant flux Defocused beam [1] Gigax et. al. , Journal of Nuclear Materials 465 (2015) 343 -348 [2] Getto et. al. Journal of Nuclear Materials 465 (2015) 116 -126 13

Defocused beam irradiation result • • • 3. 5 Me. V Fe 2+ defocused beam, 50 dpa, 500 ºC Annealed 316 stainless steel Void swelling ~ 6 %. [3] Gabriel Meric de Bellefon 2018 Ph. D. thesis, University of Wisconsin-Madison 14

IBL Usage in 2017 -2018 § 22% UW-Madison committed non-NSUF projects § 50% NSUF, Nuclear Energy Enabling Technologies (NEET), Nuclear Energy University Program (NEUP) projects • Oak Ridge National Laboratory “Mechanical Properties and Radiation Resistance of Nanoprecipitates-Strengthened Advanced Ferritic Alloys” NEET 2015 • University of Wisconsin-Madison “Radiation Damage in High Entropy Alloys” NSUF RTE 2018 § 28% others • Naval Nuclear Laboratory “Proton Irradiation and TEM Analysis of Zr -4” § Total 350 hours/year § Still able to accommodate considerably more hours. 15

NEUP funded project - 709 steel: ion irradiation damage • 100 dpa peak damage, 350 ºC. • Frank loop size 10 -16 nm, increasing with damage level. • Frank loop density – (5 -9)× 1021 m-3. [4] He L, Mo R, Tyburska-Pueschel B, Xu H, Chen T, Tan L, Sridharan K 2017 Materials Research Society Spring Meeting 16

Comparison of Fe 2+-irradiated 709 and 316 H 709 316 H 54 dpa TEM sample thickness: 95 nm 42 dpa, 56 nm thick 63 dpa, 69 nm thick Sample Damage (dpa) Dislocation loop density (m-3) 709 54 5. 9× 1021 709 90 6. 0× 1021 316 H 42 2. 5× 1022 316 H 63 2. 5× 1022 316 H 97 2. 2× 1022 Counted only dislocation loops visible to g=[002]. 17 [4] He L, Mo R, Tyburska-Pueschel B, Xu H, Chen T, Tan L, Sridharan K MRS Spring 2017

Ion Concentration (at. %) Swelling (%) Irradiation induced volume density change in 316 H • 100 dpa peak damage, 350 ºC. • Electron volume density inversely correlates with ion implantation profile. 316 H: Average swelling=0. 15± 0. 05 % [5] He L, Xu H, Tan L, Voyles P, Sridharan K 2017 Microscopy & Microanalysis Meeting 18

NEET project – Nanoprecipitatesstrengthened advanced ferritic alloys Ni. Al • • Ni. Al • Fe-12 Cr-3 W-3 Ni -3 Al-1 Nb 4 Me. V Fe 2+, 170 dpa, 475 ºC B 2 -structure Ni. Al particles fully coherent with matrix 5 nm Li He, Lizhen Tan, Kumar Sridharan 19

DOE funded project – redeposition layers in DIII-D fusion facility Courtesy of C. Wetteland D. Donovan, University of Tennessee-Knoxville Particle Induced X-Ray Emission (PIXE) 2 Me. V proton beam, 6 mm 2 spot size, ~10 μC of charge. • PIXE can offer higher resolution/sensitivity scans than x-ray fluorescence (XRF) with a better calibrated depth into the surface (~20 microns). • PIXE’s background significantly reduced as compared to using electrons (EDS). 20

Access UW-IBL • UW-IBL is continually improved to meet the research needs involving ion irradiation. • Access IBL through NSUF proposal: – DOE Consolidated Innovative Nuclear Research (CINR), annual submission. – Rapid Turnaround Experiments, three calls a year. – https: //nsuf. inl. gov/ 21

Contact Details, rates, and application forms: § http: //ibl. ep. wisc. edu § https: //nsuf. inl. gov/ Contacts: § Li He - (li. he@wisc. edu) – NSUF POC § Kumar Sridharan (kumar. sridharan@wisc. edu) § Adrien Couet (couet@wisc. edu) § Todd Allen (todd. allen@wisc. edu) § Kim Kriewaldt – lab manager, technical questions only (kriewald@engr. wisc. edu) 22

Acknowledgements § Iron irradiation of 709 and G 92 § US Department of Energy Nuclear Engineering University Program (NEUP) under project Number 14 -6346 § Iron irradiation of ferritic alloys § Nuclear Energy Enabling Technologies (NEET): Reactor Materials FY 2015 Award § Analysis of redeposition layers in DIII-D § US Department of Energy under DE-AC 05 -00 OR 22725 (ORNL), DE-FG 0207 ER 54917 (UCSD), and DE-FC 02 -04 ER 54698 (General Atomics). 23