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					                             BNL - FNAL - LBNL - SLAC

               LARP Collaboration Meeting 13
                      Port Jefferson
                      Nov. 4-6, 2009

            Magnet Radiation Issues
                     Giorgio Ambrosio
                           Fermilab

Outline:
- Summary of Radiation Hard Insulation Workshop
- Updates and other programs
- Options
             Rad-Hard Insulation Workshop
                    FNAL April 07
  AGENDA:

  1:30       Introduction                                          20   G. Ambrosio
             LARP Magnets Mechanical Analysis                      20   I. Novitzky
             Radiation Environment in the LARP IR Magnets          30   N. Mokhov
             and Needs for Radiation Tests
             Radiation Effects to Nb3Sn, Copper and Inorganic      20   A. Zeller
             Materials
  3:30       Break                                                 20
             Current Knowledge of Radiation Tolerance of           20   R. Reed
             Epoxies
             Radiation-Resistant Insulation for High-Field         30   M. Hooker
             Magnet Applications
             New Wind-and-React Insulation Application             10   M. Hooker
             Process
             Discussion about test needs, samples, and available        All
             test facilities
             Summary and plans                                          All

Talks on the LARP plone at:
https://dms.uslarp.org/MagnetRD/SupportingRD/Rad_Hard_Insul/Apr07_workshop/
                                                                      2
                           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”




                                                                   3
      Rad-Hard Workshop
                                                                          Fermilab




 Radiation Environment in the LARP IR
Magnets and Needs for Radiation Tests

                                                                  Original slides,
                                                                  I added comments
                                            Nikolai Mokhov        and underlines
                                                Fermilab

                                        Rad-Hard Insulation Workshop
                                            Fermilab, Batavia, IL
                                               April 20, 2007


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 emax 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 rest
Total 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,    D (MGy/yr)    Flux n>0.1 MeV
                                  1034 cm-2s-1   at 107 s/yr   (1016 cm-2)

 70-mm NbTi                       1              7             0.3
 quads

 100-mm Nb3Sn                     10             35            1.6
 quads
                                                                         Both
 Block-coil Nb3Sn                 10             25            1.2       increase
 quads                                                                   5 times
 Dipole-first IR                  10             15            0.7
 Nb3Sn

Shell-coil quads at 1035:
Averaged over coils D ~ 0.5 MGy/yr, at slide bearings ~ 25 kGy/yr
   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 <Eg> ~ 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
                         end parts, cables etc.?
   kGy/yr onApr. 18-20, 2007
    Rad-Hard – Fermilab,
  Radiation Effects on Nb3Sn,
copper and inorganic insulation

            Al Zeller
             NSCL/
              MSU
      General limits for Nb3Sn:
                                    Nikolai:
                                    Dose: 200 MGy
                                    Neutrons: 1021 n/m2
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
       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 be
able to irradiate Nb3Sn    Hot samples 
                             transp/handling isuess
Need place to test samples   -Should we do it?
                             - Can we use results of
                             other programs (ITER, …)?
           Copper
Radiation increases resistance
                             Should check if
From the Wiedemann-Franz-Lorenz lawour
                             this may affect
                             magnets:
      at a constant temperature is smaller but
                             flux
             λρ = constant   energy is higher



    Thermal conductivity decreases

 Minimum propagating zone decreases:
       Lmpz = ((Tc-To)/j2)

               So Lmpz -> λ
This is 40 cm3/g   Problem:
in one year!
                  Gas evolution
        Ranges from 0.09 for Kapton to
        >1 cm3/g/MGy for other epoxies
      Gas is released upon heating to room
                   temperature



        Can cause swelling, rupture of
   containment vessel or fracturing of epoxy
Big caution: Damage in inorganic materials
is temperature dependent.
Damage at 4 K, for some properties, is 100
times more than the same dose or fluence
                                             This is
absorbed at room temperature.                concerning!
Since Nb3Sn has a useful fluence limit of
1023 n/m2, critical properties of inorganic
insulators should be stable to 1025 n/m2
at 4 K.
Note that electrical insulation properties are
10 times less sensitive than mechanical ones.
Radiation Tolerance of Resins

                                 We need epoxy
                                 resin or
    Rad-Hard Insulation Workshop equivalent
       Fermilab, April 20, 2007  material for coil
                                 impregnation

                 Dick Reed
                 Cryogenic Materials, Inc.
                 Boulder, CO
    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
   blend
Cyanate ester    ~0.5        ~0.5        100 MGy/40-80 MPa
TGDM              0.4         0.1         50 MGy/45 MPa
BMI               0.3        <0.1        100 MGy/38 MPa
PI                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.)
                            Radiation-Resistant Insulation
                          For High-Field Magnet Applications
                                                              Presented by:

                                                       Matthew W. Hooker
                                                               Presented at:

                                            Radiation-Hard Insulation Workshop
                                           Fermi National Accelerator Laboratory
                                                        April 2006
                                                                                                       NOTICE
These 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.

2600 Campus Drive, Suite D • Lafayette, Colorado 80026 • Phone: 303-664-0394 • www.CTD-materials.com
                                                                                Proposed
                                                                                substitute for
                                  CTD-403                                       epoxy resin

                                                                      100
                                                                                                            CTD-403@50°C
• CTD-403 (Cyanate ester)                                              80




                                                    Viscosity (cPs)
     - Excellent VPI resin                                             60

     - High-strength insulation from                                   40
       cryogenic to elevated temperatures
                                                                       20
     - Radiation resistant
                                                                        0
     - Moisture resistance improved over                                    0   10   20   30    40   50     60   70   80   90
       epoxies                                                                                 Time (hrs)


• Quasi-Poloidal Stellarator
     -   Fusion device
     -   Compact stellarator
     -   20 Modular coils, 5 coil designs
     -   Operate at 40 to >100°C
     -   Water-cooled coils


                                                                        QPS
24                                          Radiation-Resistant Insulation for High-Field Magnets
                                                                                                             Proposed
                                    Braided Ceramic-Fiber                                                    substitute for
                                       Reinforcements                                                        S2 glass

• 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

  25                                                            Radiation-Resistant Insulation for High-Field Magnets
       Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
                              CTD Irradiation Timelines

            Epoxy-Based Insulations                                          Proposed
                     SBS                                              Ceramic/Polymer Hybrids
            E-beam Irradiated at 4 K                                 SBS & Gas Evolution at 4 K



                    1992-93                                                  2008-2009
  HEP




                     SSC                                                     DOE SBIR
                      GA                                                       NIST

          1988                                                                         Not
          CTD Founded                                                                  completed
Fusion




                        1992-1998              2000-2003            2005-2007
                          ITER                 DOE SBIR             DOE SBIR
                       Garching/ATI               ATI                MIT-NRL


             Epoxy-Based Insulations    Epoxies & Cyanate Esters   Resins & Ceramic/Polymer Hybrids
                   SBS, Compression        SBS, Compression        SBS, Compression
            Shear/Compression at 4 K         Gas Evolution         Adhesive Strength
                                                                   Gas Evolution

                                       Gas evolution , irradiation at:
     26                                        Radiation-Resistant Insulation forC
                                              70 C                         80 High-Field Magnets
                                                    Is this low shear
                                                    strength acceptable
                       Insulation      Irradiations in a “small” area?
                           Nikolai:
                           Peak dose in 1 year
                                          120




                                                           Short-Beam-Shear Strength (MPa)
• Fiber-reinforced VPI systems                                                                100                                       CTD-101K
                                                                                                                                        CTD-403
                                                                                                                                        CTD-422
     - CTD-101K (epoxy)                                                                        80


     - CTD-403 (cyanate ester)                                                                 60

     - CTD-422 (CE/epoxy blend)                                                                40


• Insulation performance                                                                       20
                                                                                                        Test Temperature: 77 K
     - Shear strength most affected                                                             0
                                                                                                    0        20      40          60   80       100     120
       by irradiation
                                                                                                                     Radiation Dose (MGy)
     - Compression strength largely                                                          2000




                                       Compression Strength (MPa)
       un-affected by irradiation
                                                                                             1500
• Ongoing irradiations
     -   Ceramic/polymer hybrids                                                             1000

     -   CTD-403                                                                                                                            CTD-101K
                                                                                             500                                            CTD-403
     -   20, 50, & 100 MGy doses
                                                                                                                                            CTD-422
                                                                                                        Test Temperature: 77 K
     -   Expect to complete by 8/07
                                                                                               0
                                                                                                    0        20      40      60      80        100     120
                                                                                                                    Radiation Dose (MGy)

27                                    Radiation-Resistant Insulation for High-Field Magnets
                                                                  2009 data
                    Radiation Resistance

• Insulation irradiations at Atomic                                 77 K
  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                                       77 K
     - 340 K irradiation temperature


28                                     Radiation-Resistant Insulation for High-Field Magnets
                       Radiation-Induced 2009 data
                         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                                     Irradiated at ATI, Vienna, Austria


• Test results
     - Cyanate esters show lowest
       gas evolution rate of VPI
       systems
     - Epoxies have higher gas-
       evolution rates
     - Results consistent with
       relative SBS performance


29                                      Radiation-Resistant Insulation for High-Field Magnets
                               Proposed 4 K Irradiation


• Low-temperature irradiations
                                                                                                                   Dewar
     - Linear accelerator facility
     - CTD Dewar design                                                   Specimen
                                                                           Position                                 Window
• Insulation characterization
     - Short-beam shear
     - Gas evolution
     - Dimensional change
• Insulations to be tested
     - Ceramic/polymer hybrids
     - Polymer composites
     - Ceramic insulations




30                                                            Radiation-Resistant Insulation for High-Field Magnets
     Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
                              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
                                                                      31
                     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   32
LARP 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?
                                  How do we want to proceed:
                                  new task, WG, core progr.,… ?

                                        G. Ambrosio - Long Quadrupole   33
LARP CM13 - BNL, Nov. 4-6, 2009
EXTRA
           Quad IR: Fluxes and Power Density (Dose)




                                               Q2B
Rad-Hard – Fermilab, Apr. 18-20, 2007
                       LARP Insulation Requirements


                                                                                   CTD-1202/CTD-CF-200
Design Parameter                                Design Value
                                                                                       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)

                                                                                       Planned testing to
Mechanical Cycles                                     10,000
                                                                                         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


36                                                            Radiation-Resistant Insulation for High-Field Magnets
     Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
                                         Enhanced Strain in
                                    Ceramic-Composite Insulation

               200
                            Tensile Test, ASTM D3039                                             Graceful Failure
                            77 K
               150
Stress (MPa)




               100


                                               S-2 Glass Reinforcement
                50                             Brittle Failure
                                               CTD-CF-200 Reinforcement
                                               Graceful Failure
                    0
                                                                                                                          Brittle Failure
                        0           0.2             0.4             0.6             0.8
                                     Percent Strain (%)


               37                                                            Radiation-Resistant Insulation for High-Field Magnets
                    Use or disclosure of the data contained on this page is subject to the restriction on the cover page of this document.
                       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                                     Irradiated at ATI, Vienna, Austria


• Test results
     - Cyanate esters show lowest
       gas evolution rate of VPI
       systems
     - Epoxies have higher gas-
       evolution rates
     - Results consistent with
       relative SBS performance


38                                      Radiation-Resistant Insulation for High-Field Magnets
                       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




                                                                                      QPS Test Coil
MAST Test Coil                                                                        USA
     UKAEA
                                   ITER DP Test Article
                                         JAEA


    39                                      Radiation-Resistant Insulation for High-Field Magnets
                      Radiation-Induced Gas Evolution


• Gas evolution in polymeric                                               Valve
                                                                                   Feed-through

  materials
                                                                                                                 Vacuum
      - Attributed to breaking of C-H                                                                             gauge
        bonds, releasing H2 gas
      - Gas causes swelling of insulation


• Gas evolution measurements                                                       Specimen
                                                                                    location
      - 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



 40                                                            Radiation-Resistant Insulation for High-Field Magnets
      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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