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Dynamic effects on Quadrupoles

Dynamic effects on Quadrupoles. S.Sanfilippo, N.Sammut, L.Bottura ,W.Venturini. AT-MTM. Dynamic effects on quadrupoles_1. Coupling current effects. resistive contact at cross-overs R c.  dB/dt. Advance in field D b 2  dB/dt and 1/ R c

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Dynamic effects on Quadrupoles

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  1. Dynamic effects on Quadrupoles S.Sanfilippo, N.Sammut, L.Bottura ,W.Venturini. AT-MTM

  2. Dynamic effects on quadrupoles_1 • Coupling current effects resistive contact at cross-overs Rc  dB/dt • Advance in field Db2dB/dt and 1/Rc • Allowed and non allowed multipole errors Dbrrn, Darrn. • No measurements in quadrupoles magnets for the moment.

  3. Dynamic effects on quadrupoles_2 • Decay • appears during constant current excitation. • associated with current redistribution in the superconducting cables. • result of a complex interaction: current redistribution  local field  magnetization  bore field • assume that the dynamics follows that of current diffusion: Powering history dependence

  4. Decay Measurement. Quantities measured :Integrated and local TF and harmonics as a function of time and current. System used :6-m twin rotating coil. Repeatability : 0.3 units (b2), 0.02 units (b6). • Parameters. I nominal I nominal I injection quench 50 A • Statistics : 9 MQs and 6 MQYs. Simulated Machine Cycle for MQ: decay at injection. Measurements performed after the training of the MQ,MQY up to ultimate.

  5. Decay results for MQs @760 A, 1000s

  6. Decay results for MQs (multipoles) @760 A, 1000s Feeble systematic. Significant random.

  7. Decay modelling for b2, b6. MQ

  8. Decay results for MQYs

  9. Decay results for MQYs (multipoles) @176 A, 1000s High value for a3 and a4 (systematic and random) enhanced by the behavior of SSS635!

  10. Example of SSS635. 6 units at 176 A! Decay @176 A, 1000s -2 units of decay.

  11. Decay modelling for b2, b6 MQY

  12. Decay results for TF of MQYs, MQM (block 4) average Statistic on 3 MQMs Statistic on 6 MQYs Still large random, smaller systematic than in SM18. Difficult to model (noise in the measurements).

  13. Conclusions and issues. • Decay of MQY, MQM, MQ quadrupole types: • Significant for b2 (-6 units,-4 units, -3 units), large random. • For b6 between 0.4 units and 0.6 units . • Strange behaviors in SM18 for non allowed multipoles (ex: SSS635). • Special measurements to be performed (2006, 2007). • Effect of the ramp rate (14 units foreseen for b2 for Rc~15mW, R. Wolf). • Influence of the pre-cycle on the decay (on spare magnets in 2007?). • flat-top current IFT • flat-top duration tFT • waiting time before injection tpre-injection • Injection duration.

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