Meeting Minutes from MCBRDP4 – Mon. 04 ^th April 2022

Attendees:  Arnaud Foussat, Veronica Ilardi, Francois-Olivier Pincot, Cedric Urscheler, Ahmed Benfkih, Sebastien Clement, Matthieu Canale, Luca Gentini, Pierre-Antoine Contat

Excused: Glyn Kirby, Helene Felice

• Feedback on last week AP1 impregnation, actions:
  • The initial temperature of the resin during injection was higher than on last P3 prototype due to homogenised mixer tank temperature control. The inlet temperature measurement estimated at 68 degC -70 deg C will be checked; This light increase in inlet resin temperature has some beneficial effect on viscosity. The initial measured viscosity at 70 deg C shall be reported in MIP/MTF report ( in reference ot viscosity at 60 deg C of 100 cPs).
  • It was confirmed that the intermediate soaking plateau at 80 deg C as described in the procedure EDMS 2493897 was not applied as not relevant for CCT volume of resin and because a outgassing at 110 deg C is added. The procedure of impregnation is under review and shall be approved for next AP2 (MOP-MCBRD Impregnation (under pressure) )
  • The respective temperature plateaus from P-T diagram of gelling and curing 110 degC- 6 h, 125 degC-16 h
  • Outgassing at 110 degC was performed with background pressure of 10^-2 mbar which is better level than on the P3. The process was followed by a flushing with N2 gas for 2 hours which shall be added in procedure.
  • In the case of P4 prototype it was noticed a short resin injection of 30 mins, comparable to 1.5h in P3. The difference might come from mainly two sources : The initial viscosity and the design deviation on the inner former Ground insulation ( one Kapton layer 125 microns thick removed). In order to retroactively inject the leftover resin in the outlet reservoir into the mould the process of Milking cycle was applied added by successive breaking of applied pressure followed by vacuum pumping cycles up to 4 times. This allowed to successfully inject up to 2.5 kg resin comparable with 2.4 kg in P3. The reference amount of resin mass controlled by flowmeter will be added in procedure and MIP as a control point. AF pointed out that it is remarkable than the volume of removed Kapton layer is equivalent to 100 g of CTD resin  ( density 1.03 g/cc). This milking process description should be added in the procedure in case short injection is observed ( <1.5 h)
  • The P-T diagram of AP1 is an outcome as part of the MIP inspection reporting, under retrieving
  • The expected automated capacitance measurement was not ready on time as the impregnation time was commonly anticipated by a day ( Fridays are avoided). As pointed out, the impregnation was one week behind schedule. The preparation of hardware will be checked in advance for next AP2 and this control step should be added as part of the MIP check list points in order to decide to launch impregnation. As a first indications the Capacitance values (nF) initially at 60, 110 deg C, 125 degC to be extracted.

• • The new set of three T sensors installed on the inner former Inner surface show a maximum thermal gradient of 5 deg C
  • Next operations are QC electrical test on AP2 as key controls of insulation GND, impedance spectrum references. The magnetic measurement is expected to be done on AP1 from week 15.

Winding of AP2 preparation :

• MTF, winding procedure
  • The creation MTF structure was delayed due to some issue with new process. HL QA team is working on it. If needed a follow up meeting with Hector Gavela will be organised.
  • The update of winding procedure (EDMS 2002853) is on going for our approval before start of winding next week.
  • VI will confirm the availability of resources to resume of AP2 winding in next 2 weeks, considering vacations

• SC wire spool repair option, qualification plan of liquid PI repair procedure
  • For time reason the repair process to be implemented on the fault wire spool shl rely on past Kapton tape repair around the wire defect. Details to be drafted in the procedure. This sppol repair is prerequisite to start AP2 winding
  • The new Polyimide liquid repair, polymerised at high temperature shall be qualified on dummy wire looking at optimised thermal curing cycles, peeling strength test.

• Feedback on AP2 components,  open issues
  • Iron keys :
    • Following last meeting with workshop, metrology the geometrical local deviations up to 20 microns should be corrected by hand polish. It will be organised trial insertion checks on  AP2 external tube grooves. The check of tolerances for assembly into laminations shall be checked. To forward metrology reports to Pietro for his knowledge.
    • Laminations delivery is expected end April, Metrology control to be included.
      •        Two new Ultem connection and jump boxes under completion next week per latest dimensions per drawings LHCMCBRDC0036, 0040
      •        P. Moyret from workshop is founding out on schedule to deliver new set of G10 end rings per latest drawings LHCMCBRDC0038, 39 under fabrication at Resarm 

• Presentation of new Design drawings by M Canale
  • LHCMCBDT0091_Assembly VPi mould detail drawing is completed, under revision following comments given:  ¾ inlet connectors type to be updated.
  • LHCMCBRDC0003_Assembly drawing of Aperture with update information on the Kapton holes dimensions and positions to be performed. Under work. The main comment is that a detail section view of the oblong hole pin should be added.

• Updated Project schedule, not discussed, link to PDF added for your information: EDMS 2665603 v.5 "Schedule of MCBRDP4"