1. Superconducting Magnet Group Future of HQ coils S. Caspi 8/25/2011

2. Superconducting Magnet Group HQ Status and Performance Assessment We had 5 tests - HQ01a-e All tests used a mix of 54/61 and 108/127 conductor Voltage breakdown (HQ01a,b tests) Insulation damage (HQ01a,b tests) Broken strands (coil #10) Spring-back after reaction Unusual (inverted) ramp rate performance (HQ01c test) Low plateau and “holding” quenches (HQ01c test, 70%) Highest plateau 85%-86% (HQ01d,e tests) Mid-plane quenches Identified high pressure as the root cause of poor performance (Coils are under excessive pressure during curing and reaction) S. Caspi

3. Superconducting Magnet Group HQ future plans Discussed at CM16: The following changes were implemented in coil #14: –Reduce strand diameter and cable size (0.778 strand –Increase islands gaps (coil #14) –Make room for coil expansion during reaction (in progress, coil #14) –Increase layer-to-layer and coils-to-shoes insulation (in progress) –Coil #14 just finished reaction –Revise protection heaters design (not implemented) –Revise coil cross-section and coil-end (not implemented) S. Caspi

4. Superconducting Magnet Group Cable with core A core has shown a good improvement in ramp rate performance. A core maybe needed to meet performance in the LHC A core will may degrade mechanical performance A core will add an uncertainty, a new variable to the current program Test two HQ magnets - with and without a core What will be the impact the LHQ (Giorgio, Helene) S. Caspi

5. Superconducting Magnet Group HQ future coils In 2012 LARP’s plan is to make 4 HQ coils only Resources will be diverted to start working on LHQ Possible future scenarios: Scenario #1: –4 HQ coils in 2012 – with core –4 LHQ practice coils in 2012-2013 – with core –No HQ coils in 2013 Scenario #2: –4 HQ coils in 2012 – 3 without core, 1 with core –4 HQ coils in 2013 – with core –4 LHQ practice coils in 2012-2013 – with core – 2 complete HQ tests – one without core, one with core S. Caspi