• Summary of the design, construction, assembly and magnetic measurements of the Variable Bend for the CLIC DR
  • SmCo was used on the low field sides because of its resistance to radiation. Suggestion to consider NbFeB permanent magnet material, due to reduced cost, and easier manipulation. -> ACTION: Elettra team to provide synchrotron radiation heat load expectations at the dipole magnets location
  • Positioning of the poles should be better then 100μm. This tolerance and size of the poles (wideness) is driven by field quality requirements
  • Need to be very careful for inserting permanent magnet for assembly, this took around 2 days per module, i.e. ~10 days for the full assembly
  • Possible aggressive machining or annealing of the ARMCO part for the low field part may be the reason for the discrepancy of around 5-6% of integrated field
  • 4mm of horizontal displacement of the magnet could solve this, the field quality is preserved but gap is reduced
  • The field quality is measured to be excellent
  • ARMCO blocks re-purchased in order to understand and mitigate this discrepancy
• Proposal for a Variable bend dipole for ELETTRA SR
  • Longitudinal dependence of the multi-poles, in particular of b2 would be desirable for understanding the impact to beam dynamics -> ACTION: CIEMAT team to provide figures to CERN for beam dynamics estimates
  • It would be good to evaluate field interference with neighbouring quadrupoles in the ELETTRA SR 2.0 configuration -> ACTION: CIEMAT team to model field interference for the new longitudinal variable design
  • Difference of using RBEND or SBEND in MADX optics should be evaluated  -> ACTION: CERN
  • Analytical solution for achromats should be extended to edge dipoles -> ACTION: CERN
  • As the call for tender for ELETTRA dipoles is scheduled for 2023, it would be interesting to study the possibility to get a VADER type of magnet with ~2 T peak field and also explore the gain of shaping the longitudinal profile of the dipoles at the edges of the achromat -> ACTION: CERN, ELETTRA
  • It may be difficult to get the sharp fall of the field for the edge dipoles, it should be understood how this was achieved in the ESRF dipoles (see https://accelconf.web.cern.ch/IPAC2014/papers/tuzb01.pdf, https://accelconf.web.cern.ch/ipac2016/papers/tupmb001.pdf) -> ACTION: CIEMAT
• Status of the ELETTRA upgrade
  • The aperture (from pole to pole) of the dipoles could be reduced by ~5 mm (i.e. from 22 to 17mm).
  • It would be important to estimate Touschek and IBS impact for new ELETTRA design, in particular for such a low momentum compaction factor -> ACTION: CERN
  • The VADER permanent magnet dipole could be tested in the machine in 2028
  • Temperature stability  need to be defined as it influences the magnet design. In the present storage the temperature stability peak-to-peak is -0.6 C (see https://accelconf.web.cern.ch/ipac2017/papers/wepva052.pdf) -> ACTION: ELETTRA
• Discussion
  • KYMA is in contact with Chinese provider for permanent magnet and iron material -> ACTION: KYMA to communicate B-H characteristics to CIEMAT
  • It is important for KYMA to be able to measure components for tuning them, so schedule should not be delayed further