Hilumi WP3 meeting, 1 October 2014 MQYY Testing Ramp rates G. Willering Hilumi WP3 meeting, 1 October 2014 01-10-2014 – MQYY testing and ramp rate– Gerard Willering – TE/MSC-TF

Some magnet details Inductance 5.85 mH Operating temperature 1.9 k Source EDMS 1366554 (on 26-09-2014) Inductance 5.85 mH Operating temperature 1.9 k Nominal current 15.7 kA Short sample limit 19.6 kA Margin on loadline 20 % Cold mass outer diameter 498 mm Magnetic length 3.83 m Conductor LHC type 2 (36 strands of 0.825 mm NbTi Cold mass weigth 7 ton Stored energy 0.73 MJ (at nominal current) 1.14 MJ (at short sample) 1/16/2019 Document reference

Can we test it? Magnet fits in our “Long Crystat” PC available: 20 kA, 25 V, 1-quadrant Warm circuit 2 V to 14 V (switch is 2 V, resistance is 0.5 mΩ) dI/dt ramp up limit at 10 V/6 mH > 1300 A/s (faster at lower current) dI/dt ramp down limit at -2 V/6 mH ~ -300 A/s (faster at higher current) Request: Ramp down from 9.6 kA to 4.8 kA for the squeeze. With 100 A/s this will take 48 s. MQ magnets (same cable, smaller B/I) do not show quenchback at this ramprate and current. 1/16/2019 Document reference

How can we protect it? Quench Heaters – not foreseen CLIQ – not foreseen Self protected – no Energy extraction – quench protection relies on energy extraction 30 MIIts are allowed for this cable at 6 T to reach 300 K is 30, (LHC design report). The detection time is sufficient for 15.6 kA, but for 19.6 kA it is uncomfortably close to the limit. Off course this is a worst case calculation, in reality we profit from resistance buildup in the coil during quench. Stored energy Stored energy at 19.6 kA is 1.1 MJ. If all the stored energy is dissipated in the bath the cryostat is safe, but most of the energy will be dissipated in the dump resistor. VoltageMaxEE (V) 1000 700 Current (kA) 19.6 15.7 R_EE (mΩ) 51.0 64.1 35.7 44.9 τ (s) 0.11 0.09 0.16 0.13 MIIts during decay (MIIts) 22.0 11.1 31.5 15.9 t_detection+validation (ms) 21 78 -4 58 1/16/2019 Document reference