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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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