Attendees:  Arnaud Foussat (AF), Veronica Ilardi (VI), Francois-Olivier Pincot (F-O), Barthi Verma (BV), Sebastien Clement (SC), Glyn Kirby (GK), Roland Piccin (RP), Lucio Fischarelli (LF), Piotr Tomasz Rogacki (PTR) 
 

Excused: Helene Felice, Davide Tommasini

AGENDA items:

1. - Status of AP1 ( post curing, WMM last outcome)
2. - Plan and process for repair of the SC NbTi wire insulation with liquid PI, including electrical test plan
3. - Winding status of AP2
4. - QA, open NC
5. - AOB

• Status of AP1 (Claret colored) manufacture
  • Post curing repair: The post curing phase to be applied on the AP1 is agreed at 110 deg C-24h after checks of impacts of thermal cycles onto the young modulus properties. The related NC 2733865 covers all findings from the resin tests :
    • EDMS 2664034 v.1 "CTD101K epoxy resin system"
    • EDMS 2732953 v.1 "DMA temperature sweep of CTD101K with different curing cycles"
  • WMM: L. Fiscarelli presented results of AP1 Warm magnetic measurement of aperture on bench supported through on side keys ( see slides, Data https://edms.cern.ch/document/2736120/1)
    • The measurements include all end fringe fields, involving a mole length of 130 mm, some overlap of 65 mm, a reference of  35 mm measurement diameter. The AP1 exhibit record excellent harmonica value on b3, b5 less than 1 unit on average in the straight region ( factor two less with respect to the past Gold aperture)
    • The field angle of AP1 is measured in relative as the aperture is not precisely aligned wrt. Gravity, however the datas show a minimal angle variation of the field along the aperture within 0.1 mrad. It was discussed that a adapted jig will be designed to check on AP2 to be fixed on lateral key slots in order to support the inclinometer within a target of 0.1 mrad.
    • LF confirmed that it would be quite useful to perform also AP2 WMM when it is ready for comparison and data analysis.

• SC strand polyimide insulation repair development
  • Most of the units length of SC NbTi strand (0.825 mm diameter) polyimide tape present a few punctual electrical insulation defects along kms and detected by Hi pot test performed by suppliers
  • Those defects need to be repaired locally. The usual repair way so far was to use a 70 microns thick tape in a U shape but this not so easy to apply without creating overthickness.
  • One solution that SMT wish to develop to make a repair on wires spool is the use of liquid polyimide coating
  • B. Verma mentioned some first results of curing temperature investigation of Pyre M-L polyimide enamel, stored at -20 degC tested on flat copper surface. A curing at 130 degC for 8 mins could be envisaged.
  • The vendor specifies a high viscosity at RT of 13 000 cPs with a drop of 2000 cPs/10 degC
  • Both PI properties and wire insulation repair process below were discussed and shall be investigated to be used on the CCT winding :
    • Pristine properties of liquid PI :
      • Adhesion strength to substrate ( before / after thermal cycle),
      • pre surface treatment of the wire insulation,
      • viscosity of Liquid at working operational temperature,
      • dielectric strength
    • Insulation appliance and test on wire
      • Application process of enamel with control of thickness ( expected thickness of 50-70 micrometers max)
      • Dielectric strength test of repaired defectuous wire samples, number of tests and samples type to be discussed with F-O and RP once a process is selected
        • Test at RT after 77 K thermal cycles
• Status of AP2 manufacture
  • The recent NC 2737025 on damaged turn insulation observed in the AP2 grooves on the head tips will be further investigated. The direction of the helical insulating PI tape will be checked against the guides. Winding trials will be done on former with smoother ribs edges to check possible impact.
  • AP2 inner layer winding passed the electrical test at 500 V.\
  • Outer layer winding is being completed this week followed by splicing.

• QA NC:
  • Apart form the mentioned active NCs in progress, the following NCs were listed and identified as ready for approval:
    • NC 2734568 : Inner former insulation in V1
    • NC 2736119 : Resarm G10 parts modified in V1
    • NC 2736192 : Ground insulation around staged pins in V1