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 Jefferson Nov. 4-6, 2009

2 Talks on the LARP plone at: Rad-Hard Insulation Workshop FNAL 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 , 2007 Radiation Environment in the LARP IR Magnets and Needs for Radiation Tests Rad-Hard Insulation Workshop Fermilab, Batavia, IL April 20, 2007 Fermilab Rad-Hard Workshop Nikolai Mokhov Fermilab Original slides, I added comments and underlines Original slides, I added comments and underlines

Rad-Hard – Fermilab, Apr , 2007 OUTLINE IR Energy Deposition-Related Design Constraints Basic Results for LHC IR at Nominal Luminosity Dose in IR Magnets at for 3 Designs Particle Energy Spectra etc. Radiation Damage Tests

Rad-Hard – Fermilab, Apr , 2007 LHC IR QUENCH LIMITS AND DESIGN CONSTRAINTS Quench limits and energy deposition design goals: NbTi IR quads: 1.6 mW/g (12 mJ/cm 3 ) DC (design goal 0.5 mW/g) Nb 3 Sn 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 Nb 3 Sn 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 , 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: 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 Nb 3 Sn coils 40 MGy/yr at & 10 7 s/yr

Rad-Hard – Fermilab, Apr , 2007 Peak Dose & Neutron Fluence in SC Coils IR magnetsLuminosity, cm -2 s -1 D (MGy/yr) at 10 7 s/yr Flux n>0.1 MeV (10 16 cm -2 ) 70-mm NbTi quads mm Nb3Sn quads Block-coil Nb3Sn quads Dipole-first IR Nb3Sn Shell-coil quads at : Averaged over coils D ~ 0.5 MGy/yr, at slide bearings ~ 25 kGy/yr Both increase 5 times

Rad-Hard – Fermilab, Apr , 2007 Radiation Damage Tests (1) 1. Peak dose in the LHC Phase-2 Nb 3 Sn 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 ~ 7 MeV and ~ 40 MeV: test coil samples (and other magnet materials) with electron beams. 2.Hadron flux seems OK for T c and I c, but needs verification for B c2. Hadron fluxes (DPA) are dominated by neutrons with ~ 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 , 2007 Radiation Damage Tests (2) 3.Propose an experiment with Nb 3 Sn 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 Nb 3 Sn, copper and inorganic insulation Al Zeller NSCL/ MSU

General limits for Nb 3 Sn: 5 X 10 8 Gy (500MGy) end of life T c goes to 5 K – 5 X n/m 2 I c goes to 0.9 I c0 at 14T – 1 X n/m 2 B c2 goes to 14T - 3 X n/m 2 NOTE: E n < 14 MeV Damage increases as neutron energy increases Nikolai: Dose: 200 MGy Neutrons: n/m 2 Nikolai: Dose: 200 MGy Neutrons: n/m 2

Important Note All of the radiation studies on Nb 3 Sn are 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 Nb 3 Sn 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, …)?

Copper Radiation increases resistance

From the Wiedemann-Franz-Lorenz law at a constant temperature λρ = constant Thermal conductivity decreases Minimum propagating zone decreases: L mpz =  ( (Tc-To)/  j 2 ) So L mpz -> 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 evolution Ranges from 0.09 for Kapton to >1 cm 3 /g/MGy for other epoxies Gas is released upon heating to room temperature Problem: This is 40 cm 3 /g in one year!

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 absorbed at room temperature. Since Nb 3 Sn has a useful fluence limit of n/m 2, critical properties of inorganic insulators should be stable to n/m 2 at 4 K. Note that electrical insulation properties are 10 times less sensitive than mechanical ones. This is concerning!

Radiation Tolerance of Resins Rad-Hard Insulation Workshop Fermilab, April 20, 2007 Dick Reed Cryogenic Materials, Inc. Boulder, CO We need epoxy resin or equivalent material for coil impregnation

Estimate of Radiation-Sensitive Properties Resin Gas Evolution Swelling 25% reduction: (cm 3 g -1 MGy -1 ) (%) dose/shear strength (4,77K) DGEBA, DGEBF/ anhydride MGy/75 MPa amine MGy/75 MPa cyanate ester ~0.6 ~1.0 ~ 50 MGy/45-75 MPa blend Cyanate ester ~0.5 ~ MGy/40-80 MPa TGDM MGy/45 MPa BMI 0.3 < MGy/38 MPa PI 0.1 < 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 Workshop Fermi 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 Phone: NOTICE These SBIR data are furnished with SBIR rights under Grant numbers DE-FG02-05ER84351 and DE-FG02-06ER 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 Magnets 24 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 QPS Proposed substitute for epoxy resin

Radiation-Resistant Insulation for High-Field Magnets 25 Braided Ceramic-Fiber Reinforcements 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

Radiation-Resistant Insulation for High-Field Magnets 26 CTD Irradiation Timelines 1988 CTD Founded Proposed Ceramic/Polymer Hybrids SBS & Gas Evolution at 4 K DOE SBIR MIT-NRL Resins & Ceramic/Polymer Hybrids SBS, Compression Adhesive Strength Gas Evolution ITER Garching/ATI DOE SBIR ATI Epoxy-Based Insulations SBS, Compression Shear/Compression at 4 K Epoxies & Cyanate Esters SBS, Compression Gas Evolution Epoxy-Based Insulations SBS E-beam Irradiated at 4 K DOE SBIR NIST SSC GA Fusion HEP Gas evolution, irradiation at: 70 C 80 C Gas evolution, irradiation at: 70 C 80 C Not completed

Radiation-Resistant Insulation for High-Field Magnets 27 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 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 Magnets 28 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 2009 data

Radiation-Resistant Insulation for High-Field Magnets 29 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 data

Radiation-Resistant Insulation for High-Field Magnets 30 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 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 Nb 3 Sn 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? G. Ambrosio - Long Quadrupole 33 LARP 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

Rad-Hard – Fermilab, Apr , 2007 Quad IR: Fluxes and Power Density (Dose) Q2B

Radiation-Resistant Insulation for High-Field Magnets 36 LARP Insulation Requirements Design ParameterDesign Value CTD-1202/CTD-CF-200 Performance Compression Strength*200 MPa650 MPa (77 K) Shear Strength40-60 MPa110 MPa (77 K) Dielectric Strength1 kV14 kV (77 K) Mechanical Cycles10,000 Planned testing to 20,000+ cycles Relative Cost** *200 MPa is yield strength of Nb 3 Sn **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 Magnets 37 Enhanced Strain in Ceramic-Composite Insulation Graceful Failure Brittle Failure 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 Magnets 38 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 Magnets 39 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 Coil UKAEA ITER DP Test Article JAEA QPS Test Coil USA

Radiation-Resistant Insulation for High-Field Magnets 40 Radiation-Induced Gas Evolution Gas evolution in polymeric materials  Attributed to breaking of C-H bonds, releasing H 2 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.