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DO WE NEED TO MODEL HYSTERESIS ? EPISODE II

FiDeL meeting, 9 th June 2009. DO WE NEED TO MODEL HYSTERESIS ? EPISODE II. E. Todesco Magnets, Superconductors and Cryostats Group Technology Department, CERN. Ackowledgements : W. Venturini Delsolaro , M. Giovannozzi , W. Herr. CONTENTS. Two types of problems related to hysteresis

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DO WE NEED TO MODEL HYSTERESIS ? EPISODE II

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  1. FiDeL meeting, 9th June 2009 DO WE NEED TO MODEL HYSTERESIS ?EPISODE II E. Todesco Magnets, Superconductors and Cryostats Group Technology Department, CERN Ackowledgements: W. VenturiniDelsolaro, M. Giovannozzi, W. Herr

  2. CONTENTS • Two types of problemsrelated to hysteresis • Magnetscrossingzero (correctors+MQT) • Correctors having a decayat injection (spool pieces) • Magnetwithdecreasingcurrent (MQY MQM) • Update on situation for MQM MQY, including IP2

  3. SQUEEZE - MQY • During squeeze, some MQY ramp down up to 700 A • In IP2 they go down up to 700 A (for 7 TeV) – 400 A for 4 TeV • The hysteresisat 700 A is about 4 units, at 400 A is 10 units

  4. SQUEEZE – MQM 4.5 K • During squeeze, some MQM at 4.5 K ramp down up to 400 A in IP5 • This gives 2 unitserror in q5.ip5, 26 unitserror in q6 ip5

  5. SQUEEZE – MQM 4.5 K • The error in q6.ip5 (and q6.ip2) becomes relevant belowb*=1.5 m • Note thatatb*=0.55 m the 26 units are relative to 14 T/m of gradient – effect to bechecked • At 4 TeVitis 60 units

  6. SQUEEZE – MQM 1.9 K • Withpresentopticsthere are no issue withhysteresis for the MQM at 1.9 K • This is the case of IP5 and IP1, q7 to q9: they do not ramp down

  7. SQUEEZE – MQM 1.9 K • Withpresentopticsthere are no issue withhysteresis for the MQM at 1.9 K • This is the case of IP2, q7 to q10: they do not ramp down

  8. SQUEEZE – MQM 1.9 K • Withpresentopticsthere are no issue withhysteresis for the MQM at 1.9 K • This is the case of IP8, maximum error of 2 units

  9. CONCLUSIONS • Squeeze of MQM MQY: • We have some cases of errorslargerthan 5 unitswithpresentoptics (up to 30 units, possibly more at 4 TeV) • Analysis of the impact on the beamdynamicsisongoing, • … but itcouldbemuch more withotheroptics • It wouldbe a pity to discoverduringbeamcommissioningthatsomeopticscannotbeusedbecause of thismissingfeature • Wesuggest to implement the two branches in LSA • FiDeL model is fine, the two branches canbegenerated by changing the sign of the Dcmagnetization component • Still to bediscussed and finalized: • Magnetcrossingzerocurrent

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