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Cold test general presentation
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Europe/Zurich
30/7-010 (CERN)
Cold test general presentation
Here are the main points that I retain from it :
Powering test (V. Di Capua)
- Training is fine up to ultimate with history. Behaviour similar to other CCT magnets
- Always precursor in ropes 8, 9, 10 and quench in rope 7, indicating a movement of the rope at the top of the groove
- No precursor on Subscale 2,
- Action: check the post-mortem study for detachment of ropes 8,9,10.
- Quench propagation analysis shows clear and coherent longitudinal and turn-to-turn propagation
- Quench back contribution is significantly reduced at 1.9 K.
- Variability in measured QI due to heating of the varistors.
- Splices are good: 1.2 mOhm.
- RRR is good: ~190.
Quench simulations and FQPC (M. Wozniak)
- Simulation not optimized, running on 2 softwares 2.5 day long.
- Varistor heating is integrated to simulation
- At 4.2 K, QI within 3%. Is this integrated parameter a good variable to validate simulation? 4.2K vs 4.5 K?
- At 1.9 K, it is quite off. By changing thermal contact one can fit the 1.9K but then it does not work anymore at 4.2K.
- It seems that original decay (not based on QB) is underestimated. Could this lead to difference after. The first drop should be better fitted.
- FQPC: no propagation observed in the coil up to 90 ms after quench start in the FQPC
- Action: work on field discharge with current
- Action: use the simulation with iron instead of Al.
Magnetic measurements (M. Pentella)
- Good agreement at the centre for the 3 planes
- Field along the cross section is away from simulation
- Integral is also away from simulation with a higher gradient from inside to outside the curvature.
- Action: Thermal contraction should be better analysed
- Mysterious oscillations in the transfer function while ramping with long period of 60 s. Amplitude and phase unchanged at 4.5K and 1.9K.
Optical fibre (No presentation)
- 1 out of 4 was working at cold
- A clear pattern is observed in correlation with the winding turns. The pattern evolves with current, and
- More post processing is required to get a better image, including comparison with FEM.
Acoustic sensors (M. Janitschke)
- Able to see the quenches with clear frequency signature
- During ramp: all the minor events are also recorded : no amplitude correlation (too many factors). Frequency signature similar to quench event
- Sensors 3 and 4 are very clear, 2 is so so and 1 is disqualified
- ToF study does not bring clear answers.
Future on Fusillo
- Subscale 3 impregnated with filled wax.
- Iron shell to replace the Aluminium (thermal contraction?, protection ?)
- Can the next shell be dry cooled.
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