slide1
Download
Skip this Video
Download Presentation
Progress Since Last Meeting

Loading in 2 Seconds...

play fullscreen
1 / 24

Progress Since Last Meeting - PowerPoint PPT Presentation


  • 82 Views
  • Uploaded on

Surface Effects and Retention of Steady State 3 He + Implantation in Single and Polycrystalline Tungsten. S.J. Zenobia, G.L. Kulcinski, E. Alderson, G. Becerra, B. Cipiti, R. Radel, J. Shea, G. Downing, R. Cao, L. Snead, R. Noll, and D. Savage HAPL Meeting-LANL April 8th, 2008

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Progress Since Last Meeting' - cana


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Surface Effects and Retention of Steady State 3He+ Implantation in Single and Polycrystalline Tungsten

S.J. Zenobia, G.L. Kulcinski, E. Alderson, G. Becerra, B. Cipiti, R. Radel, J. Shea, G. Downing, R. Cao, L. Snead, R. Noll, and D. Savage

HAPL Meeting-LANL

April 8th, 2008

Fusion Technology Institute

University of Wisconsin-Madison

progress since last meeting
Progress Since Last Meeting
  • Three single-crystalline (SCW) and three polycrystalline (PCW) tungsten specimens were acquired from Dr. Lance Snead and ORNL
  • Both SCW and PCW were implanted in the UW IEC device with 30 keV 3He+ to fluences of 5x1016 cm-2 at ~850 °C and 4x1017 and 5x1018 cm-2 at ~1000 °C
  • Pre and post-irradiation SEM analysis was done on each sample to diagnose surface morphology changes
  • Helium retention fluences and retention ratios were measured in all specimens using 3He(d,p)4He nuclear reaction analysis (NRA)
  • Retained He fluence, retention ratios and depth profiles were measured by 3He(n,p)T neutron depth profiling (NDP)

2

uw ion beam assisted analysis techniques elastic recoil detection erd nuclear reaction analysis nra

500 μm Al foil

2 MeV D+ beam

Solid-State Detector

p (14.7 MeV)

Tungsten Sample

α-particle

UW Ion Beam Assisted Analysis Techniques: Elastic Recoil Detection (ERD) & Nuclear Reaction Analysis (NRA)
  • NRA uses the 3He(d,p)4He nuclear reaction
  • D+ beam easily penetrates the He implanted region
  • He retention data was acquired for tungsten samples at implant fluences between 5x1016 – 5x1018 He+/cm2
  • Previous work by Radel used the ion beam for ERD analysis of HAPL samples
  • Helium retention and depth profile was determined for polycrystalline W between 1018 - 1019 He+/cm2
  • O4+ beam only penetrated 130 nm

UW 1.7 MeV

Tandem Accelerator

3

nist cold neutron facility and the neutron depth profiling ndp analysis technique
NIST Cold Neutron Facility and the Neutron Depth Profiling (NDP) Analysis Technique
  • NDP uses a cold neutron source and the 3He(n,p)T nuclear reaction
  • Neutrons are ideal for depth profiling and measuring concentration (negligible energy loss)
  • He retention for tungsten samples was acquired from Greg Downing at the NIST facility

4

results
Results
  • Morphology changes (SEM)
  • Helium retention (NRA, NDP, & ERD)
  • Materials viability assessment

5

polycrystalline tungsten irradiated with 3 he to 4x10 17 and 5x10 18 cm 2 at 1000 c

5x1018 cm-2

4x1017 cm-2

1 μm

1 μm

1 μm

Polycrystalline Tungsten Irradiated with 3He+ to 4x1017 and 5x1018 cm-2 at ~1000 ºC

7

single crystalline tungsten implanted with 3 he to 4x10 17 and 5x10 18 cm 2 at 1000 c

5x1018 cm-2

Pores

1 μm

1 μm

Single Crystalline Tungsten Implanted with 3He+ to 4x1017 and 5x1018 cm-2 at ~1000 ºC

4x1017 cm-2

9

comparison of single polycrystalline tungsten implanted with 3 he to 5x10 16 cm 2 at 850 c

1 μm

1 μm

Comparison of Single & Polycrystalline Tungsten Implanted with 3He+ to 5x1016 cm-2 at ~850 ºC

Single-crystalline

Polycrystalline

10

comparison of single polycrystalline tungsten implanted with 3 he to 4x10 17 cm 2 at 1000 c

1 μm

1 μm

Comparison of Single & Polycrystalline Tungsten Implanted with 3He+ to 4x1017 cm-2 at ~1000 ºC

Single-crystalline

Polycrystalline

11

comparison of single polycrystalline tungsten implanted with 3 he to 5x10 18 cm 2 at 1000 c

1 μm

1 μm

Comparison of Single & Polycrystalline Tungsten Implanted with 3He+ to 5x1018 cm-2 at ~1000 ºC

Single-crystalline

Polycrystalline

12

nra and ndp show retained he fluence saturates at 4x10 17 cm 2 in tungsten
NRA and NDP Show Retained He Fluence Saturates at ~4x1017 cm-2 in Tungsten

NRA = Nuclear Reaction Analysis

NDP = Neutron Depth Profiling

13

slide14
Comparing ERD with NRA & NDP Techniques Confirms Retained He Fluence Does Not Exceed ~4x1017 cm-2 in Tungsten

*

NRA = Nuclear Reaction Analysis

NDP = Neutron Depth Profiling

ERD = Elastic Recoil Detection

14

*R.F. Radel and G.L. Kulcinski (2007)

observations on retained he fluence in single and polycrystalline tungsten
Observations on Retained He Fluence in Single and Polycrystalline Tungsten
  • Saturation of retained He fluence occurs prior to extensive surface morphology change
  • Maximum retained He fluence is observed near 4x1017 cm-2

15

tungsten s helium retention ratio decreases with increasing implant fluences
Tungsten’s Helium Retention Ratio Decreases with Increasing Implant Fluences

NRA = Nuclear Reaction Analysis

NDP = Neutron Depth Profiling

16

all techniques indicate an increased retention ratio of he in w with decreasing implant fluence
All Techniques Indicate an Increased Retention Ratio of He in W with Decreasing Implant Fluence

*

NRA = Nuclear Reaction Analysis

NDP = Neutron Depth Profiling

ERD = Elastic Recoil Detection

17

*R.F. Radel and G.L. Kulcinski (2007)

observations on the he retention ratio in single and polycrystalline tungsten
Observations on the He Retention Ratio in Single and Polycrystalline Tungsten
  • Surface damage increases despite a decreasing He retention ratio

18

fluence to full power day equivalent fpd in the reference hapl chamber
Fluence to Full Power Day Equivalent (FPD) in the Reference HAPL Chamber

10 – 30

keV

10 – 100

keV

Full He+ Spectrum

0.1 FPD

1017 cm-2

2.2 FPD

0.02 FPD

1018 cm-2

22.3 FPD

0.9 FPD

0.2 FPD

1019 cm-2

223 FPD

8.5 FPD

2.0 FPD

*Reference HAPL chamber with 10.5 m radius and 5 Hz duty cycle

19

slide20

Extensive Surface Damage

Relatively Unaffected

Summary of Examined Materials Viability (Cipiti, Radel, and Zenobia)

SiC

PCW

PCW

CCV

SiC

CCV

20

observations on fw candidate materials for the hapl chamber
Observations on FW Candidate Materials for the HAPL Chamber
  • SCW, W-coated TaC foams, and PCW appear to be the most robust materials
  • SiC, velvet materials (examined to date), and W-Re alloys respond poorly to ion implantation
  • Abatement of the ion threat spectra is necessary to extend the lifetime of any of the examined materials to practical lifetimes

21

future work

Carbon Velvet Spikes

Length ~ 1 mm

Diameter (base) ~ 35 μm

Future Work

Future Work Cont. ?

  • Depth profiling analysis for SCW and PCW specimens is currently underway
  • Focused ion beam (FIB) milling will be used to determine the penetration depth of pores below the tungsten surface
  • Surface erosion and roughness will be measured using optical profilometry to give mass loss estimates

Photo courtesy of Thad Heltemes - UW

22

conclusions
Conclusions
  • The threshold for pore formation after 3He+ implantation in both SCW and PCW is observed between 5x1016 - 4x1017 cm-2, becoming extensive by 5x1018 cm-2
  • The retained helium fluence in tungsten saturates at ~4x1017 He/cm2
  • The He retention ratio in tungsten decreases with increasing implant fluence, showing strong He trapping efficiency at low fluences
  • He+ abatement is required to extend the lifetimes of any of the IEC examined materials

23

questions

Samuel Zenobia

University of Wisconsin-Madison1500 Engineering DriveMadison, WI 53706(608) [email protected]

Questions
ad