Choose timezone
Your profile timezone:
11T dipole technical meeting - New plan - Session 1
→
Europe/Zurich
Executive summary of the discussion
Participants:
B. Bordini, L. Bottura, A. Devred, H. Felice, S. Izquierdo Bermudez, J.C. Perez, F. Savary, D. Tommasini, G. Willering
Summary:
There is a general consensus on the fact that Case II would necessitate such an amount of work that we may not be able to deliver magnets for LS3. It should anyhow be put in the plan (scope and extent of the work to be defined), as it will provide part of the foundations for the future projects. On the contrary, Case I, upon condition it would provide satisfactory results, would likely allow us to deliver on time two magnets for installation during LS3.
With regard to Case I, and prior to launch any new tests at cold, it is necessary to determine what to do, in particular as to the modification of the assembly conditions and of the preload on the coil ends (in both radial and longitudinal directions). For this, we need:
- To review the cold tests data for both the models and the series magnets;
- To pursue the work already started on the FE modelling (E. Gautheron, C. Garion et al.), and analytical calculations (G. Spigo).
It was suggested to identify someone to take the lead on the mechanical aspects and related structural analyses. Brainstorming specific to the topic is needed. There are many parameters that can play a role, e.g. friction, thickness of the end plates, etc... A parametric analysis would be very useful.
Even though mechanical measurements at cold without powering would already provide useful information (it might very well be that cracking of the Nb3Sn filaments occur during cool down and / or warm up), powering, and thermal cycles will be necessary. It appears indeed that it is the sequencing of powering (and quenches at sufficiently high current) and thermal cycle, which trigger degradations.
Powering at 4K would be more informative as to the understanding of conductor degradation. Testing the magnet to short sample limit at 4K is a good way to check its health.
Quench antennas, magnetic measurements, mechanical measurements, and also tests to ultimate at 1.9K, will be needed.
Diagnostic at low current is not sufficient to reveal issues relating to filament cracking.
The amount of work, even for Case I, is significant. These activities need to be well integrated in the work plan of the group, with adequate allocation of resources.
The magnets S4, or S5, could be used for a cold tests campaign. One of the two magnets will have to be dismounted in order to install the mechanical instrumentation, and to change, if needed, the preload conditions in the coil ends. It will be worth reassembling the magnet with an aperture equipped with brand new coils, and another aperture equipped with already used / tested coils. A list of the possible options shall be drawn out.
There are minutes attached to this event.
Show them.