BNL - FNAL - LBNL - SLAC Magnet Radiation Issues Giorgio Ambrosio Fermilab Outline: - Summary of...

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

https://dms.uslarp.org/MagnetRD/SupportingRD/Rad_Hard_Insul/Apr07_workshop/

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


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


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.


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


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


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).


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.?

Radiation Effects on Nb3Sn, copper and inorganic

insulation

Al Zeller

NSCL/

MSU

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, …)?

CopperRadiation increases resistance

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


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


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


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 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-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


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


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.,… ?

EXTRA


Quad IR: Fluxes and Power Density (Dose)

Q2B


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



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




• 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


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


Valve

Feed-through

Vacuumgauge

Specimenlocation

Valve

Feed-through

Vacuumgauge

Specimenlocation


• 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


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