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

2. Some magnet details Inductance 5.85 mH Operating temperature 1.9 k
Source EDMS (on )
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 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

3. 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

4. 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