Choose timezone
Your profile timezone:
RFQ2 measurement in B152 discussion
→
Europe/Zurich
6/2-008 (CERN)
Three parameters changed during the manipulations to prepare the RFQ with new supports;
- the resonance frequency,
- the Q factor, and
- the field distribution.
- The Q0 factor is 12% higher than before and finally at the expected value and this is the only good news.
- The resonance frequency decreased by ~35kHz and there is an unexpected elastic change of ~40kHz whenever the RFQ2 is put under vacuum.
- Under vacuum the RFQ2 reaches a resonance frequency that is outside the tuning range of the thermal tuning station.
- The field distribution must have changed and is outside specification, but is stable since the RFQ2 was put on the jacks.
- The quadrupole component reaches +/-2% in deviation instead of +/-1%, the dipole components reach about +/-5% instead of +/-2%.
- Up to now it is not clear what caused the changes.
- An analysis of the influence of vacuum ports showed that the installation of vacuum sleeves only accounts for a small fraction of the changes.
- It is therefore not possible to install a simple fix on the vacuum ports.
- A further test on the end flanges that seems unlikely to be the culprit, will be undertaken.
- Independent of what caused the changes, it is clear that for operation on Linac4 the change in resonance frequency must be compensated.
- The aim is to correct the resonance frequency and the field distribution by the least number of operations
- Lee will check with the sensitivity matrix that he had extracted during the tuning process previously which tuners could best compensate the deviations
- The hope is that only 4 to 8 tuners out of 32 would need to be retouched.
- In order not to recur a similar situation in future transport movements on the RFQ2, a handling test needs to be undertaken with the re-installation of the auxiliary supports.
- RF verification measurements need to be undertaken at every stage of that test.
There are minutes attached to this event.
Show them.
