FERMILAB HIGH POWER
TARGET R&D PROGRAM
NBI 2012 P. Hurh (FNAL) Nov. 8, 2012
Overview
Fermilab High Power Target Facility Needs
High Power Target Challenges
High Power Target R&D Activities
Future Plans
Current Target Facilities
Fermilab Accelerator Division operates 3 target
facilities:
P-bar Source (off) – 70 kW proton beam on inconel
(nickel alloy) target with Be cover (110 kW/mm2)
NuMI/MINOS – 400 kW proton beam on graphite
(carbon) target (14 kW/mm2)
Soon to be 700 kW beam for NOvA
MiniBooNE – 32 kW proton beam on beryllium target
(1 kW/mm2)
Note: Values in red refer to total beam power divided by nominal 3 sigma spot size,
not energy deposition in target and not peak values
Near to Mid-Term Future Target
Facilities (<10 years)
Currently have resources working on:
ANU/NOvA - 700 kW p beam on graphite (15 kW/mm2)
LBNE-1- 700 kW p beam on graphite (Be?) (15 kW/mm2)
Mu2e – 8 kW - 8 GeV p beam on W (0.4 kW/mm2)
G-2 – 27 kW - 8 GeV proton beam on inconel (??)
Just starting to consider:
ORKA – 74 kW – 95 GeV proton beam on platinum (??)
NuSTORM – 100 kW- 60 GeV proton beam on Ta or W
(??)
Note: Values in red refer to total beam power divided by nominal 3 sigma spot size,
not energy deposition in target and not peak values
Note: High Z targets will have much higher energy deposition per proton
Mid-Term to Far-term (>10 years):
Project X Reference Design
Project X Staging Layout
Fermilab HPT R&D Program
Approach:
Large number of facilities contemplated and budgetary
uncertainties
Address HPT R&D at fundamental level not necessarily
specific to any single facility
Build HPT technology and infrastructure as a “core
competency” at Fermilab (such as SRF)
Be poised to embark on informed design of the next
large machine (Nu Factory/Muon Collider)
HPT Challenges
Thermal Shock (Stress Waves)
Heat removal
Radiation Damage
Radiation Accelerated Corrosion
Spatial Constraints and Shielding
Residual Radiation
Manufacturing techniques
Physics Optimization Not just targets, but entire target systems (beam windows, collection
optics, absorber, decay pipe, etc.)
Thermal Shock
Fast expansion of material surrounded by cooler material creates a sudden local area of compressive stress
Stress waves (not shock waves at these load rates) move through the target
Plastic deformation and/or cracking can occur
Ta-rod after irradiation with 6E18 protons in 2.4 s
pulses of 3E13 at ISOLDE (photo courtesy of J. Lettry)
Simulation of stress wave propagation in Li lens
(pbar source, Fermilab)
Heat Removal
About 7.5 kW total energy deposited (NOvA – 700 kW primary beam target)
Easy to remove with water
Tritium production
Hydrogen gas production
Thermal shock in water (Water Hammer)
BUT:
Radiation Damage
Tungsten cylinders irradiated with 800 MeV protons and compressed to 20% strain at RT. A) Before irradiation
B) After 3.2 dpa
C) After 14.9 dpa
D) After 23.3 dpa
Data exists for neutron irradiation, less for proton irradiation
Gas production much higher for high energy particle irradiation S. A. Malloy, et al., Journal of Nuclear Material,
2005. (LANSCE irradiations)
Radiation Accelerated Corrosion
Al 6061 samples
displayed significant
localized corrosion
after 3,600 Mrad
exposure
NuMI target chase air handling condensate with pH of 2
NuMI decay pipe window concerns
R.L. Sindelar, et al., Materials
Characterization 43:147-157
(1999).
Radiation Accelerated Corrosion
MiniBooNE 25 m absorber HS steel failure
(hydrogen embrittlement from accelerated corrosion).
Fermilab HPT R&D Activities
Radiation Damage Research
Found to be most cross-cutting HPT challenge (PASI 2012)
Opportunity for leveraging fission/fusion knowledge base and materials science expertise
RaDIATE Collaboration
Thermal Shock Research
Verification of simulation tools (elastic & plastic)
Strain rate dependencies
Failure criteria (when is a target really failed, Hartsell Talk)
Many other ongoing efforts (autopsies, cooling studies, novel target concepts (pebble bed, Be spheres)
RaDIATE Collaboration
Radiation Damage In Accelerator Target Environments
From the MOU:
The Participants intend for the research program to include those
activities which develop a better understanding of radiation
damage mechanisms and the associated thermal and mechanical
properties response for materials of interest to future high
power proton beam target facilities.
Enlisting the aid of fission and fusion power materials
experts as well as current researchers in the accelerator
domain
Initial Collaborators: FNAL, BNL, STFC, PNNL, Oxford
RaDIATE Collaboration Capabilities
Each Institution brings unique and overlapping expertise and capabilities
Fermilab: Operating experience with Target Facilities and Target design expertise
BNL: Extensive Materials Science expertise and BLIP irradiation station (current site for HE proton radiation damage research under Nick Simos)
STFC: Operating experience with ISIS, Target design experience, Materials Science expertise and more
PNNL: Extensive radiation damage (nuclear reactor) experience, hot lab capability with advanced research instruments (SEM, TEM, Atom probe, tensile, fatigue, etc…)
Oxford: Extensive radiation damage (nuclear reactor) experience, advanced research instruments (SEM, TEM, Atom probe, tensile, fatigue, etc…), advanced techniques for materials evaluation (micro-mechanics)
Why use micro-mechanical testing?
Useful where only small samples are available Cost
Processing
Need for a sample design that can be machined in surface of bulk samples
Suitable for measuring individual microstructural features
Samples that can be manufactured quickly and reproducibly
1um
3m 10m
4m
3m
3m
D.E.J Armstrong 2011
19
Microcantilever Manufacture
10m
07/11/2012 D.E.J Armstrong 2011
2m
Current State of the Art
07/11/2012 D.E.J Armstrong 2011
General boundary
S3 - twin
Testing of micro-cantilevers
07/11/2012 D.E.J Armstrong 2011
Fracture at 600oC
1µm
RaDIATE Activities
Stage 1: Exploratory and Development (6 month)
Recruit materials science post-doc based at Oxford
Develop experimental research program
Consider graphite, beryllium, tungsten, and C-C composite initially
Survey of existing, irradiated sample material
Continue radiation damage studies at BLIP (Simos talk)
Just started
Stage 2: Experimental Stage (1-2 years)
Irradiate new materials or use existing targets/windows?
Intense PIE (perhaps made easier by micro-mechanics)
RaDIATE Activities (con’t)
Stage 3: Report writing (1 year)
Publications
Set direction for future work
Disseminate findings to HPT community
Looking for additional collaborators
Contact me if interested
Thermal Shock R&D
Elastic response simulations have been verified
Plastic and failure, not so much Some work at GSI by Lettry with U beam
Classic definition of failure (yield) perhaps too conservative
Failure of target is generally if it holds together for the next pulse!
Evidence that materials can take much more than we have thought in the past (beam windows especially)
High strain rate
Plastic deformation “pre-loading”
Ductility at higher temperatures (annealing of rad damage as well!)
Possible testing at Hi-Rad Mat
Talk by Brian
Hartsell on
initial studies
Future HPT R&D Program Plans
Continue leading RaDIATE
Continue Thermal Shock R&D
Continue other studies as resources allow
Build HPT expertise as a “core competency” rather than specific to a particular project
Coordinate R&D activities globally
In times of shrinking budgets, must be efficient
By pooling resources can attack larger problems to gain fundamental understanding, applicable to many future target facilities
But compromises will have to be made and accepted when doing general research rather than specific research