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ArcHalfCellMock-up Meeting #2
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Europe/Zurich
Notes of Meeting Arc Half Cell Mockup #2
21st June 2022
List of people attending the meeting:
F.Carra (chaiman), K. Artoos, J. Bauche, L. Baudin, A. Bertarelli, K. Hanke, R. Losito, JP. Tock, F. Valchkova, F. Zimmermann
Slides of the presentations as well as video recording of the meeting are available in the Indico page related to the meeting (https://indico.cern.ch/event/1171609/)
Agenda:
- Picks-ups from FCC week (F. Carra)
- Status on Magnet System Design (J. Bauche)
1)
Federico showed slides presenting the FCC outstanding questions presented by Tor in Accelerator Pillar meeting. Federico and Lucie will collect a table gathering the parameters (tolerances/geometric characteristics) relevant to start working on technical solutions. Frank commented that the parameters may change in the future, but he acknowledged that a starting base is needed.
Some components are on preliminary design: booster dipole (presented in FFC week), booster quadrupole and collider quadrupole (first step is magnetic design after that the output in term of geometry can be deducted). For the moment, these are not mature yet to enter in a more detailed design phase, but their evolution will be observed by the Arc Half-Cell Mockup project until they reach a high enough state of maturity.
Federico and Lucie will start to work on the mechanical stability and vibration of the supporting structures, based on the pre-design from Fani.
The interfaces between Magnet and Vacuum systems have to be studied to avoid interferences. Dipole/dipole interface configuration will depend on the progress of TE-VSC in Memory Shape Alloy technology used as flange. Dipole/Quadrupole interface has not been designed yet.
Federico informed that a proposition for a design job description about the systems interfaces has been drafted, and it will be sent to Frank and Tor for approval. Frank agreed.
2)
Jeremie presented the status of the design on the magnet system (which has evolved compared to the CDR).
Arc dipole have 1 busbar/polarity in copper cooled by a water circuit.
At the interconnection the flange footprint constrains the connection of the busbar, that tends to increase the length of the interconnection.
The gap, currently foreseen, in between the magnets of the 25-m-long dipole is 300 mm.
Considering the dipole cross-section: the absorbers of the vacuum system need to be water cooled, more space might be needed in between the two beams. The interbeam distance (currently 300 mm most likely need to be increased).
Frank asked how many dipole/dipole interconnection are needed (depending on the schema chosen 1x24 m, or 2x12 m or 3x8 m).
Jeremie commented that if TE-VSC can improve the D/D flanges (currently based on the design of Super KKE) based on the SMA technology, the gap might be reduced, and the magnet field could cover the entire interconnection.
Federico asked if there is a hard limit for the inter beam distance, in terms of beam optics. Frank answered: “no hard limit”. Jeremie said that dipole design can be slightly modified to accommodate the space modification needed for vacuum system, in case the interference is reasonably small.
Alessandro asked about the diameter of the cooling water pipe.
Jeremie said that they are not yet defined but only a small courant density is circulating in the magnet. The system was preliminary designed without water cooling system, but active cooling is requested to avoid too much heat losses to the ventilation system. Busbar will be made of extruded copper.
Kurt asked about the absence of bellow in between 12-m-long magnets, and consequences on alignment.
Jeremie said that even with “1” 24-m-long vacuum chamber, 3 points of support/12-m-long element are foreseen. It will be bellows at the Dipole/Quadrupole interface but nothing is designed yet here… BPM position not even fixed.
Federico asked who will take care of the collider quadrupole re-design: R&D working group? Jeremie is the responsible, Roberto confirmed.
Actions follow up
- Define an updated table of key requirement and parameters related to the design on the collider and the booster. This table should be based on CDR and updated following presentations given at FCC week. à Federico, Lucie to trigger the action, and to crosscheck the tables with the stakeholders.
- Meet with Helene, Kurt, Michael G. to start the discussion about the technical issue of stability à Federico, Lucie.
- Complete the proposition for a design job description about the Magnet/Magnet and Magnet/Vacuum interfaces and send it to Frank and Tor à Federico
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