BNL - FNAL - LBNL - SLAC
Magnet Radiation Issues Giorgio Ambrosio
Fermilab
Outline:- Summary of Radiation Hard Insulation Workshop- Updates and other programs- Options
LARP Collaboration Meeting 13 Port JeffersonNov. 4-6, 2009
2
AGENDA: 1:30 Introduction 20 G. Ambrosio LARP Magnets Mechanical Analysis 20 I. Novitzky Radiation Environment in the LARP IR Magnets
and Needs for Radiation Tests 30 N. Mokhov
Radiation Effects to Nb3Sn, Copper and Inorganic Materials
20 A. Zeller
3:30 Break 20 Current Knowledge of Radiation Tolerance of
Epoxies 20 R. Reed
Radiation-Resistant Insulation for High-Field Magnet Applications
30 M. Hooker
New Wind-and-React Insulation Application Process
10 M. Hooker
Discussion about test needs, samples, and available test facilities
All
Summary and plans All Talks on the LARP plone at:
https://dms.uslarp.org/MagnetRD/SupportingRD/Rad_Hard_Insul/Apr07_workshop/
Rad-Hard Insulation WorkshopFNAL April 07
3
Questions
Develop plan to arrive to these answers:
“Can this magnet withstand the expected radiation dose?”
We should be able to reply either:
- “Yes it can, and we have data to demonstrate it”
- “No it cannot, but we have tested a TQ with an insulation/impregnation scheme that can withstand the expected dose”
Rad-Hard – Fermilab, Apr. 18-20, 2007
Radiation Environment in the LARP IR Magnets and Needs for Radiation
Tests
Rad-Hard Insulation Workshop Fermilab, Batavia, IL
April 20, 2007
FermilabRad-Hard Workshop
Nikolai Mokhov
Fermilab
Original slides,I added comments and underlines
Original slides,I added comments and underlines
Rad-Hard – Fermilab, Apr. 18-20, 2007
OUTLINE
• IR Energy Deposition-Related Design Constraints• Basic Results for LHC IR at Nominal Luminosity• Dose in IR Magnets at 1035 for 3 Designs• Particle Energy Spectra etc.• Radiation Damage Tests
Rad-Hard – Fermilab, Apr. 18-20, 2007
LHC IR QUENCH LIMITS AND DESIGN CONSTRAINTS
Quench limits and energy deposition design goals:
NbTi IR quads: 1.6 mW/g (12 mJ/cm3) DC (design goal 0.5 mW/g)
Nb3Sn IR quads: ~5 mW/g DC (design goal 1.7 mW/g)
Energy deposition related design constraints: Quench stability: keep peak power density max below the quench
limits, with a safety margin of a factor of 3. Radiation damage: use rad-resistant materials in hot spots; with
the above levels, the estimated lifetime exceeds 7 years in current LHC IRQ materials; R&D is needed for materials in Nb3Sn magnets.
Dynamic heat load: keep it below 10 W/m. Hands-on maintenance: keep residual dose rates on the
component outer surfaces below 0.1 mSv/hr. Engineering constraints are always obeyed.
Rad-Hard – Fermilab, Apr. 18-20, 2007
Quad IR: Power Density and Heat Loads vs L*
The goal of below the design limit of 1.7 mW/g is achieved with:Coil ID = 100 mm. W25Re liner: 6.2+1.5 mm in Q1, and 1.5 mm in the restTotal dynamic heat load in the triplet:
1.27, 1.47 and 1.56 kW for L*=23, 19.5 and 17.4 m
Peak dose in Nb3Sn coils 40 MGy/yr at 1035 & 107 s/yr
Rad-Hard – Fermilab, Apr. 18-20, 2007
Peak Dose & Neutron Fluence in SC Coils
IR magnets Luminosity, 1034 cm-2s-1
D (MGy/yr)at 107 s/yr
Flux n>0.1 MeV
(1016 cm-2)
70-mm NbTiquads
1 7 0.3
100-mm Nb3Snquads
10 35 1.6
Block-coil Nb3Snquads
10 25 1.2
Dipole-first IRNb3Sn
10 15 0.7
Shell-coil quads at 1035:Averaged over coils D ~ 0.5 MGy/yr, at slide bearings ~ 25 kGy/yr
Both increase 5 times
Both increase 5 times
Rad-Hard – Fermilab, Apr. 18-20, 2007
Radiation Damage Tests (1)
1. Peak dose in the LHC Phase-2 Nb3Sn coils will be
about 200 MGy over the expected IR magnet lifetime. Seems OK for metals and ceramics, not OK for organics. It is > 90% due to electromagnetic showers, with <E> ~ 7 MeV and <Ee> ~ 40 MeV: test coil samples (and other magnet materials) with electron beams.
2. Hadron flux seems OK for Tc and Ic, but needs verification for Bc2. Hadron fluxes (DPA) are dominated by neutrons with <En> ~ 80 MeV, the most damaging are in 1 to 100 MeV region. Very limited data above 14 MeV for materials of interest (e.g., APT Handbook).
Rad-Hard – Fermilab, Apr. 18-20, 2007
Radiation Damage Tests (2)
3. Propose an experiment with Nb3Sn coil fragments (and other magnet materials) at a proton facility with emulated IR quad radiation environment (done once with MARS15 for the downstream of the Fermilab pbar target). Look at BLIP (BNL), Fermilab, and LANL beams.
4. One of the important deliverables: a correspondence of data at high energies to that at reactor energies (scale?).
5. Do we need beam tests at cryo temperatures?
6. Analyze if there are other critical regions in the quads with the dose much lower than all of the above but with radiation-sensitive materials. For example, is it OK 10 kGy/yr on end parts, cables etc.?
General limits for Nb3Sn:
5 X 108 Gy (500MGy) end of life
Tc goes to 5 K – 5 X 1023 n/m2
Ic goes to 0.9 Ic0 at 14T – 1 X 1023 n/m2
Bc2 goes to 14T - 3 X 1022 n/m2
NOTE: En < 14 MeV
Damage increases as neutron energy increases
Nikolai:Dose: 200 MGyNeutrons: 1021 n/m2
Nikolai:Dose: 200 MGyNeutrons: 1021 n/m2
Important Note
All of the radiation studies on Nb3Sn are 15-25 years old and we have lots of new materials.
Need new studies
But I may be able to help.
Have funding for HTS irradiation, so may beable to irradiate Nb3Sn
Need place to test samples
Hot samples transp/handling isuess-Should we do it?- Can we use results of other programs (ITER, …)?
Hot samples transp/handling isuess-Should we do it?- Can we use results of other programs (ITER, …)?
From the Wiedemann-Franz-Lorenz law at a constant temperature
λρ = constant
Thermal conductivity decreases
Minimum propagating zone decreases:Lmpz = ((Tc-To)/j2)
So Lmpz -> λ
Should check if this may affect our magnets: flux is smaller but energy is higher
Should check if this may affect our magnets: flux is smaller but energy is higher
Can cause swelling, rupture of
containment vessel or fracturing of epoxy
Gas evolutionRanges from 0.09 for Kapton to >1 cm3/g/MGy for other epoxies
Gas is released upon heating to room temperature
Problem:This is 40 cm3/g in one year!This is 40 cm3/g in one year!
Big caution: Damage in inorganic materialsis temperature dependent.Damage at 4 K, for some properties, is 100times more than the same dose or fluenceabsorbed at room temperature.Since Nb3Sn has a useful fluence limit of1023 n/m2, critical properties of inorganicinsulators should be stable to 1025 n/m2
at 4 K.Note that electrical insulation properties are10 times less sensitive than mechanical ones.
This is concerning!
This is concerning!
Radiation Tolerance of Resins
Rad-Hard Insulation WorkshopFermilab, April 20, 2007
Dick ReedCryogenic Materials, Inc.
Boulder, CO
We need epoxy resin or equivalent material for coil impregnation
We need epoxy resin or equivalent material for coil impregnation
Estimate of Radiation-Sensitive Properties
Resin Gas Evolution Swelling 25% reduction: (cm3 g-1MGy-1) (%) dose/shear strength (4,77K)DGEBA,DGEBF/ anhydride 1.2 1-5 5 MGy/75
MPa amine 0.6 1.0 10 MGy/75
MPa cyanate ester ~0.6 ~1.0 ~ 50 MGy/45-75 MPa blendCyanate ester ~0.5 ~0.5 100 MGy/40-80 MPaTGDM 0.4 0.1 50 MGy/45
MPaBMI 0.3 <0.1 100 MGy/38
MPaPI 0.1 <0.1 100 MGy
Other Factors Related to Radiation Sensitivity of Resins
Radiation under applied stress at low temperatures - increases sensitivity (US/ITER/model coil)
Higher energy neutrons (14 Mev) are more deleterious than predicted (LASL)
Irradiation enhances low temperature creep (Osaka U.)
Presented at:
Radiation-Hard Insulation WorkshopFermi National Accelerator Laboratory
April 2006
Radiation-Resistant Insulation For High-Field Magnet Applications
Presented by:
Matthew W. Hooker
2600 Campus Drive, Suite D • Lafayette, Colorado 80026 • Phone: 303-664-0394 • www.CTD-materials.com
NOTICEThese SBIR data are furnished with SBIR rights under Grant numbers DE-FG02-05ER84351 and DE-FG02-06ER84456 . For a period of 4 years after acceptance of all items to be delivered under this grant, the Government agrees to use these data for Government purposes only, and they shall not be disclosed outside the Government (including disclosure for procurement purposes) during such period without permission of the grantee, except that, subject to the foregoing use and disclosure prohibitions, such data may be disclosed for use by support contractors. After the aforesaid 4-year period the Government has a royalty-free license to use, and to authorize others to use on its behalf, these data for Government purposes, but is relieved of all disclosure prohibitions and assumes no liability for unauthorized use of these data by third parties. This Notice shall be affixed to any reproductions of these data in whole or in part.
Radiation-Resistant Insulation for High-Field Magnets24
CTD-403
• CTD-403 (Cyanate ester)- Excellent VPI resin- High-strength insulation from
cryogenic to elevated temperatures- Radiation resistant- Moisture resistance improved over
epoxies
• Quasi-Poloidal Stellarator- Fusion device- Compact stellarator- 20 Modular coils, 5 coil designs- Operate at 40 to >100°C- Water-cooled coils
0
20
40
60
80
100
0 10 20 30 40 50 60 70 80 90
Time (hrs)
Vis
co
sit
y (
cP
s)
CTD-403@50°C
QPS
Proposed substitute for epoxy resin
Proposed substitute for epoxy resin
Radiation-Resistant Insulation for High-Field Magnets25
Braided Ceramic-FiberReinforcements
Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
• Minimizing cost- Lower-cost fiber reinforcements for
ceramic-based insulation (CTD-CF-200)- CTD-1202 ceramic binder is 70% less than
previous inorganic resin system
• Improving magnet fabrication efficiency- Textiles braided directly onto Rutherford
cable (eliminates taping process)- Wind-and-react, ceramic-based insulation
system
• Enhancing magnet performance - Insulation thickness reduced by 50%
• Closer spacing of conductors enables higher magnetic fields
- Robust, reliable insulation• Mechanical strength and stiffness• High dielectric strength• Radiation resistance
Proposed substitute for S2 glass
Proposed substitute for S2 glass
Radiation-Resistant Insulation for High-Field Magnets26
CTD Irradiation Timelines
1988CTD Founded
ProposedCeramic/Polymer Hybrids
SBS & Gas Evolution at 4 K
2005-2007DOE SBIRMIT-NRL
Resins & Ceramic/Polymer HybridsSBS, CompressionAdhesive StrengthGas Evolution
1992-1998ITER
Garching/ATI
2000-2003DOE SBIR
ATI
Epoxy-Based InsulationsSBS, Compression
Shear/Compression at 4 K
Epoxies & Cyanate EstersSBS, Compression
Gas Evolution
Epoxy-Based InsulationsSBS
E-beam Irradiated at 4 K
2008-2009DOE SBIR
NIST
1992-93SSCGA
Fu
sio
nH
EP
Gas evolution , irradiation at:
70 C 80 C
Gas evolution , irradiation at:
70 C 80 C
Not completed
Not completed
Radiation-Resistant Insulation for High-Field Magnets27
Insulation Irradiations
• Fiber-reinforced VPI systems- CTD-101K (epoxy)- CTD-403 (cyanate ester)- CTD-422 (CE/epoxy blend)
• Insulation performance- Shear strength most affected
by irradiation- Compression strength largely
un-affected by irradiation
• Ongoing irradiations- Ceramic/polymer hybrids- CTD-403- 20, 50, & 100 MGy doses- Expect to complete by 8/07
0
500
1000
1500
2000
0 20 40 60 80 100 120
Radiation Dose (MGy)
Co
mp
res
sio
n S
tre
ng
th (
MP
a)
CTD-101K
CTD-403
CTD-422Test Temperature: 77 K
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Radiation Dose (MGy)
Sh
ort
-Bea
m-S
hea
r S
tren
gth
(M
Pa)
CTD-101K
CTD-403
CTD-422
Test Temperature: 77 K
Is this low shear strength acceptable in a “small” area?
Is this low shear strength acceptable in a “small” area? Nikolai:
Peak dose in 1 year
Nikolai:Peak dose in 1 year
Radiation-Resistant Insulation for High-Field Magnets28
Radiation Resistance
• Insulation irradiations at Atomic Institute of Austrian Universities (ATI)
- CTD-403 (CE)- CTD-422 (CE/epoxy blend)- CTD-101K (epoxy)
• CTD-403 shows best radiation resistance
• CTD-422 is improved over epoxy, but lower than pure CE
• Irradiation conditions- TRIGA reactor at ATI (Vienna)- 80% gamma, 20% neutron- 340 K irradiation temperature
77 K
77 K
2009 data2009 data
Radiation-Resistant Insulation for High-Field Magnets29
Radiation-Induced Gas Evolution
• Gas evolution testing- Irradiate insulation specimens
in evacuated capsules- As bonds are broken, gas is
released into capsule- Breaking capsule under
vacuum allows gas evolution rate to be determined
• Test results- Cyanate esters show lowest
gas evolution rate of VPI systems
- Epoxies have higher gas-evolution rates
- Results consistent with relative SBS performance
Irradiated at ATI, Vienna, Austria
2009 data2009 data
Radiation-Resistant Insulation for High-Field Magnets30
Proposed 4 K Irradiation
• Low-temperature irradiations- Linear accelerator facility
- CTD Dewar design
• Insulation characterization- Short-beam shear
- Gas evolution
- Dimensional change
• Insulations to be tested- Ceramic/polymer hybrids
- Polymer composites
- Ceramic insulations
Dewar
Window
SpecimenPosition
Dewar
Window
SpecimenPosition
Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
31
Discussion
We need to optimize absorbers from a radiation damage point of view:– Detailed map of damage by Mokhov,– Effects on mechanical design by Igor (acceptable or not?)– If not, increase liners and iterate
We need to assess damage under expected dose:– Test under conditions as close as possible to operation conditions
Start testing CTD-403 (cyanate ester) or other alternative material:– Ten stack for testing: impregnation, mechanical, electrical and thermal
properties
Generate table with all materials (in magnet) and compare damage threshold with expected dose
Other Programs (incomplete list)
• NED-EuCARD: RAL started R&D on rad-hard insulation for Nb3Sn magnets– Initial focus on binder/sizing mat.
• CEA: ceramic insulation w/o impregnation– I don’t know if it’s still in progress
• CERN: proposal of an irradiation test facility that could accommodate a SC magnet (cold)– Workshop in december
• …
G. Ambrosio - Long Quadrupole 32LARP CM13 - BNL, Nov. 4-6, 2009
Options
1. Set acceptable dose with present ins./impregnation scheme optimize liners and absorbers- Do we have enough info for this plan?
2. Perform measurement in order to set previous limit- How much aperture do we expect to gain?
- What measurement should we perform?
3. Develop more rad-hard ins/impregnation scheme- What measurement should we perform?
G. Ambrosio - Long Quadrupole 33LARP CM13 - BNL, Nov. 4-6, 2009
How do we want to proceed:new task, WG, core progr.,… ?
How do we want to proceed:new task, WG, core progr.,… ?
Radiation-Resistant Insulation for High-Field Magnets36
LARP Insulation Requirements
Design Parameter Design ValueCTD-1202/CTD-CF-200
Performance
Compression Strength* 200 MPa 650 MPa (77 K)
Shear Strength 40-60 MPa 110 MPa (77 K)
Dielectric Strength 1 kV 14 kV (77 K)
Mechanical Cycles 10,000Planned testing to
20,000+ cycles
Relative Cost** 1.00 0.20-0.30
*200 MPa is yield strength of Nb3Sn
**Relative cost as compared to CTD-1012PX
Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
Radiation-Resistant Insulation for High-Field Magnets37
Enhanced Strain in Ceramic-Composite Insulation
Graceful Failure
Brittle Failure0
50
100
150
200
0 0.2 0.4 0.6 0.8Percent Strain (%)
Str
ess
(MP
a)
S-2 Glass Reinforcement Brittle Failure
CTD-CF-200 ReinforcementGraceful Failure
Tensile Test, ASTM D303977 K
Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
Radiation-Resistant Insulation for High-Field Magnets38
Radiation-Induced Gas Evolution
• Gas evolution testing- Irradiate insulation specimens
in evacuated capsules- As bonds are broken, gas is
released into capsule- Breaking capsule under
vacuum allows gas evolution rate to be determined
• Test results- Cyanate esters show lowest
gas evolution rate of VPI systems
- Epoxies have higher gas-evolution rates
- Results consistent with relative SBS performance
Irradiated at ATI, Vienna, Austria
Radiation-Resistant Insulation for High-Field Magnets39
Fabrication of Test Coils
• Successful test coils have been produced around the world using CTD’s Cyanate Ester insulations for fusion and other applications
- Mega Ampere Spherical Torus (MAST) diverter coil – United Kingdom- ITER Double Pancake test article – Japan- Quasi Poloidal Stellarator (QPS) test coils – USA (Univ. of Tennessee)
• CTD-422 used to produce accelerator magnet for MSU/NSCL
• Commercial use of CTD-403 in coils for medical systems is ongoing
MAST Test CoilUKAEA
ITER DP Test ArticleJAEA
QPS Test CoilUSA
Radiation-Resistant Insulation for High-Field Magnets40
Valve
Feed-through
Vacuumgauge
Specimenlocation
Valve
Feed-through
Vacuumgauge
Specimenlocation
Radiation-Induced Gas Evolution
• Gas evolution in polymeric materials
- Attributed to breaking of C-H bonds, releasing H2 gas
- Gas causes swelling of insulation
• Gas evolution measurements- Composite specimens sealed in
evacuated quartz capsules- After irradiation, capsule fractured
in evacuated chamber- Gas evolution correlated to
pressure rise in chamber- Dimensional change measured
Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
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