Superconducting Magnets and Materials Thrust: Impact of HFM R&D on LARP

1. Giorgio Ambrosio Fermilab General Accelerator Development Review January 24-26, 2011 Superconducting Magnets and Materials Thrust: Impactof HFM R&D on LARP

2. LARP Long Quadrupole • The LHC Accelerator Research Program is a collaboration of FNAL, BNL, LBNL, and SLAC, contributing to the LHC. Goals: • Advance International Cooperation in High Energy Accelerators • Advance High Energy Physics • Advance U.S. Accelerator Science and Technology • LARP Magnet Program Goal: • Demonstrate that Nb3Sn technology is a viable option for LHC luminosity upgrade • 1st critical milestone set in 2005: Long Quadrupole with G = 200 T/m by end of 2009 • Aperture: 90 mm; length: 3.7 m G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

3. LARP Long Quadrupole Achievements • The LQ R&D started ~1 year later than originally planned because of delays in the short model R&D; nonetheless 3 milestones were met in 2009-2010: • Gradient > 200 T/m in Nov. 2009 •  we are on track for using Nb3Sn in LHC luminosity upgrade • Same highest gradient of best short model • G = 222 T/m with LQS01b •  there are no scale-up issues • Demonstration of “good memory” after thermal cycle •  this technology can be used for accelerator magnets G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

4. Key Factors for Success • Several factors contributed to this success, among them: • Robust coil design & fabrication technology • The success rate of long coils (100 %) is better than the success rate of short coils • Excellent test facility capable of handling all challenges of this test The FNAL core program was decisive in both cases G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

5. Ex 1: Problem During LQ Coil Fabrication • Problem: strain in coil after heat treatment (HT) • Nb3Sn is strain sensitive, • Very high risk of failure • Causes: • Different thermal expansion of materials involved • Change of coil material properties during the HT • Friction and length effects • Solution: • Gaps in the pole: open before HT, closed after HT G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

6. HFM Help for Understanding and Solving problem I • Scientific and engineering expertise for developing possible explanations and methods for checking them • We could look at all possible causes and check them • Sets of experimental data from past HT of many coils in different conditions • understanding key parameters • Measurements and reports about changes of conductor dimensions during HT • allowing quantitative understanding without having to perform tests on the conductor G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

7. HFM Help for Understanding and Solving problem II • Equipments, tools and methods for exploring and checking possible explanations; and for developing and demonstrating the solution • We did a series of tests that pointed toward the right direction, and subsequently confirmed it • Practice with the solution (pole gaps), which had been used for other coil designs in the past • Past experience with the solution (adopted for a similar problem) gave us confidence and knowhow • Resources that could be quickly redirected toward this goal • This was decisive to solve the problem in a few months G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

8. Challenges of Long Quadrupole Test • Series of challenges: • Significantly higher energy than any previous Nb3Sn accelerator magnet model • Large voltage spikes (flux jumps) possibly compromising quench detection • Large number of heaters with new design and new locations (added on coil ID) • Series of upgrades to FNAL VMTF • Adaptive quench detection threshold (digital and analog.) • Symmetric grounding • Active coil-ground fault detection • Active coil-heaters fault detection • Automatic post-discharge heater tests • Independent wiring of each heater through lambda plate G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

9. HFM Help for VMTF Upgrades • Understanding of LQ needs and knowledge of VMTF features • for developing optimal list of modifications and upgrades in order to maximize chances of successful test • All modifications and upgrades were gradually implemented and tested on HFM models • Allowing fine-tuning of adaptive quench detection threshold • New tools for diagnosis and recording were developed for HFM models • such as voltage spike detection, monitoring and recording • Expertise and resources available for development, implementation and test of all these modifications G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

10. Conclusions • The HFM made very important contributions to the Long Quadrupole R&D and some achievements (2009 milestone) would have not been possible without it. • In more general terms the HFM at Fermilab plays essential roles such as: • incubator for new concepts, designs (for instance magnets for a muon collider), and technologies (for example the ceramic binder for Nb3Sn coils that is presently a LARP standard), which can be adopted by projects and programs; • and as a pool of resources and expertise that can make the difference when unexpected problems are found. G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

11. G. Ambrosio, Fermilab - DOE Proton Accel. based Physics Review June 8-12, 2009

12. LQS01b Quench History SSL at 4.5K : 240 T/m 227 Target: 200 T/m