- Slides: 40
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 Talks on the LARP plone at: 2 https: //dms. uslarp. org/Magnet. RD/Supporting. RD/Rad_Hard_Insul/Apr 07_workshop/
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 Nikolai Mokhov Original slides, I added comments 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: Nb. Ti IR quads: 1. 6 m. W/g (12 m. J/cm 3) DC (design goal 0. 5 m. W/g) Nb 3 Sn IR quads: ~5 m. W/g DC (design goal 1. 7 m. W/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 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 m. Sv/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 m. W/g is achieved with: Coil ID = 100 mm. W 25 Re liner: 6. 2+1. 5 mm in Q 1, and 1. 5 mm in the rest Total dynamic heat load in the triplet: 1. 27, 1. 47 and 1. 56 k. W for L*=23, 19. 5 and 17. 4 m Peak dose in Nb 3 Sn 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-2 s-1 D (MGy/yr) at 107 s/yr Flux n>0. 1 Me. V (1016 cm-2) 70 -mm Nb. Ti quads 1 7 0. 3 100 -mm Nb 3 Sn quads 10 35 1. 6 Block-coil Nb 3 Sn quads 10 25 1. 2 Dipole-first IR Nb 3 Sn 10 15 0. 7 Both increase 5 times Shell-coil quads at 1035: Averaged over coils D ~ 0. 5 MGy/yr, at slide bearings ~ 25 k. Gy/yr Rad-Hard – Fermilab, Apr. 18 -20, 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 <Eg> ~ 7 Me. V and <Ee> ~ 40 Me. V: test coil samples (and other magnet materials) with electron beams. 2. Hadron flux seems OK for Tc and Ic, but needs verification for Bc 2. Hadron fluxes (DPA) are dominated by neutrons with <En> ~ 80 Me. V, the most damaging are in 1 to 100 Me. V region. Very limited data above 14 Me. V for materials of interest (e. g. , APT Handbook). Rad-Hard – Fermilab, Apr. 18 -20, 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 MARS 15 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 k. Gy/yr on end parts, cables etc. ? Rad-Hard – Fermilab, Apr. 18 -20, 2007
Radiation Effects on Nb 3 Sn, copper and inorganic insulation Al Zeller NSCL/ MSU
General limits for Nb 3 Sn: Nikolai: Dose: 200 MGy Neutrons: 1021 n/m 2 5 X 108 Gy (500 MGy) end of life Tc goes to 5 K – 5 X 1023 n/m 2 Ic goes to 0. 9 Ic 0 at 14 T – 1 X 1023 n/m 2 Bc 2 goes to 14 T - 3 X 1022 n/m 2 NOTE: En < 14 Me. V Damage increases as neutron energy increases
Important Note All of the radiation studies on Nb 3 Sn 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 Nb 3 Sn Hot samples Need place to test samples transp/handling isuess -Should we do it? - Can we use results of other programs (ITER, …)?
Copper Radiation increases resistance
Should check if this From the Wiedemann-Franz-Lorenz law may affect our magnets: at a constant temperature flux is smaller but energy is higher λρ = constant Thermal conductivity decreases Minimum propagating zone decreases: Lmpz = ( (Tc-To)/ j 2) So Lmpz -> λ
This is 40 cm 3/g in one year! Problem: 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 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 Nb 3 Sn has a useful fluence limit of 1023 n/m 2, critical properties of inorganic insulators should be stable to 1025 n/m 2 at 4 K. Note that electrical insulation properties are 10 times less sensitive than mechanical ones.
Radiation Tolerance of Resins Rad-Hard Insulation Workshop Fermilab, April 20, 2007 We need epoxy resin or equivalent material for coil impregnation Dick Reed Cryogenic Materials, Inc. Boulder, CO
Estimate of Radiation-Sensitive Properties Resin Gas Evolution (cm 3 g-1 MGy-1) (4, 77 K) DGEBA, DGEBF/ anhydride amine cyanate ester blend Cyanate ester TGDM BMI PI 1. 2 0. 6 ~0. 5 0. 4 0. 3 0. 1 Swelling (%) ~1. 0 ~0. 5 25% reduction: dose/shear strength 1 -5 5 MGy/75 MPa 1. 0 10 MGy/75 MPa ~ 50 MGy/45 -75 MPa 100 MGy/40 -80 MPa 0. 1 50 MGy/45 MPa <0. 1 100 MGy/38 MPa <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-FG 02 -05 ER 84351 and DE-FG 02 -06 ER 84456. 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
CTD-403 Proposed substitute for epoxy resin • 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 24 Radiation-Resistant Insulation for High-Field Magnets
Braided Ceramic-Fiber Reinforcements Proposed substitute for S 2 glass • Minimizing cost - Lower-cost fiber reinforcements for ceramicbased 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.
HEP CTD Irradiation Timelines Epoxy-Based Insulations SBS E-beam Irradiated at 4 K Proposed Ceramic/Polymer Hybrids SBS & Gas Evolution at 4 K 1992 -93 SSC GA 2008 -2009 DOE SBIR NIST Not completed Fusion 1988 CTD Founded 1992 -1998 ITER Garching/ATI Epoxy-Based Insulations SBS, Compression Shear/Compression at 4 K 26 2000 -2003 DOE SBIR ATI Epoxies & Cyanate Esters SBS, Compression Gas Evolution 2005 -2007 DOE SBIR MIT-NRL Resins & Ceramic/Polymer Hybrids SBS, Compression Adhesive Strength Gas Evolution Gas evolution , irradiation at: 70 C 80 for. CHigh-Field Magnets Radiation-Resistant Insulation
Is this low shear strength acceptable Insulation Irradiations in a “small” area? Nikolai: Peak dose in 1 year • Fiber-reinforced VPI systems - CTD-101 K (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 - 27 Ceramic/polymer hybrids CTD-403 20, 50, & 100 MGy doses Expect to complete by 8/07 Radiation-Resistant Insulation for High-Field Magnets
2009 data Radiation Resistance • Insulation irradiations at Atomic Institute of Austrian Universities (ATI) 77 K - CTD-403 (CE) - CTD-422 (CE/epoxy blend) - CTD-101 K (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 28 77 K 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 gasevolution rates - Results consistent with relative SBS performance 29 Radiation-Resistant Insulation for High-Field Magnets
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 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-Eu. CARD: 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 • … LARP CM 13 - BNL, Nov. 4 -6, 2009 G. Ambrosio - Long Quadrupole 32
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. , … ? LARP CM 13 - BNL, Nov. 4 -6, 2009 G. Ambrosio - Long Quadrupole 33
Quad IR: Fluxes and Power Density (Dose) Rad-Hard – Fermilab, Apr. 18 -20, 2007 Q 2 B
LARP Insulation Requirements Design Value CTD-1202/CTD-CF-200 Performance 200 MPa 650 MPa (77 K) 40 -60 MPa 110 MPa (77 K) Dielectric Strength 1 k. V 14 k. V (77 K) Mechanical Cycles 10, 000 Design Parameter Compression Strength* Shear Strength Relative Cost** 1. 00 Planned testing to 20, 000+ cycles 0. 20 -0. 30 *200 MPa is yield strength of Nb 3 Sn **Relative cost as compared to CTD-1012 PX 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 Graceful Failure Brittle Failure 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 gasevolution 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 MAST Test Coil UKAEA 39 QPS Test Coil USA ITER DP Test Article JAEA Radiation-Resistant Insulation for High-Field Magnets
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 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.