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STATUS OF FIDEL

LHC commissioning working group, CERN 25 th August 2009. STATUS OF FIDEL. E. Todesco for the FiDeL team Magnets , Superconductors and Cryostats Group Technology Department, CERN. The team:

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STATUS OF FIDEL

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  1. LHC commissioningworking group, CERN 25thAugust 2009 STATUS OF FIDEL E. Todesco for the FiDeL team Magnets, Superconductors and Cryostats Group Technology Department, CERN The team: • B. Auchmann, L. Bottura,M. Buzio, L. Deniau, P. Hagen,W. VenturiniDelsolaro, M. Giovannozzi, M. Lamont, S. Redaelli, V. Remondino, F. Schmidt, M. Strzelczyk, L. Walckiers, R. Wolf I wish to acknowledge L. Bottura who bravely started the project long time ago, and R. Wolf who steered it in 2008

  2. CONTENTS • Reminder of the structure • What has been donesince 2008 run • Evaluation of FiDeLparameters for harmonics (MB alreadydone) • Model update: • Penetration component • Hysteresisimplementation • Database • Documentation • Critical issues and future activities • Cycles • Tracking test • Validation

  3. REMINDER OF THE STRUCTURE • The new structure implemented in 2009 allowed to • Reduce the total numberof people involved in the project and increasetheirpercentage • More effective, less time wasted for meetings • Most of the staff dedicated to magnetanalysisiswithin one group, one section • Beforeitwas split betweenthree groups • To have only staff members in charge of the data • I wished to avoidhavingfellows or student in charge of data, to ensurecontinuity in an extremelycritical phase of the commissioning (Ex. N. Sammut, in charge of the MB data, left in March 2009) • Bi-monthly meetings • 12 meetings in January-July 2009 • Minutes on www.cern.ch/fidel

  4. REMINDER OF THE STRUCTURE • Eachmagnetfamily has a custodian (staff member) • Evaluate the parametersfrom the measurements • Follow-up specific issues • Write the documentation • Able to go back to data and performanalysisin case of need • Estimate of usedresources in January-July 2009 • About 5-6 FTE over 6 months (excluding FTE involved in measurements)

  5. CONTENTS • Reminder of the structure • What has been donesince 2008 run • Evaluation of FiDeLparameters for harmonics (MB alreadydone) • Penetration component • Hysteresisimplementation • Database • Documentation • Critical issues • Cycles • Tracking test • Validation

  6. WHAT HAS BEEN DONE IN 2009:EVALUATION OF FIDEL PARAMETERS • 2008: TF of all magnets plus fieldharmonics of MB • 2009: FiDeLparameters of all fieldharmonics • Penetration component added (needed for MQM) • Complete review of correctors has been carried out – one minormistakefound • MB to review, and to update 3-4

  7. WHAT HAS BEEN DONE IN 2009:HYSTERESIS • In some MQM during squeeze the currentdecreasesand one shouldfollow the otherbranch of the hysteresis • LSA in 2009 hadonly one branch (the lower one), giving for Q6.ip5 an error of 35 unitsatb*=0.55 m In 2009 at the end of the squeeze LSA willbethere (right place) In 2008 at the end of the squeeze LSA would have been thereinstead Than on the corresponding value of the upperbranch Q6 in IP5 during squeeze decreasing to lowcurrents – error of 30 units if hysteresisisneglected

  8. WHAT HAS BEEN DONE IN 2009:HYSTERESIS – MQM and MQY • In some MQM during squeeze the currentdecreasesand one shouldfollow the otherbranch of the hysteresis • Neglectingthiseffectis not dramatic, but has some impact on the beam (estimatesfrom Massimo) • This isalreadymodelled in the FiDeLequations • It isenough to change the sign of the DC magnetization • Decision: LSA shouldbe able to switchfrom one branch to the other oneaccording to dI/dt • Implemented in July 2009 (Marek S.) • To becheckedsoon • It willbe possible to switch off this option

  9. WHAT HAS BEEN DONE IN 2009:HYSTERESIS – SPOOL PIECES • Other types of hysteresis: • Spool pieces (MCS, MCDO) have decreasingcurrentsduring injection plateau, due to decay, and thenthey cross zerocurrentduringramp • Neglecting the hysteresis, has a negligible impact on the beam • Marginal for the sextupole spool pieces b3 to becorrected in the dipoles in one of the octants, withzerocrossingat 0.8 TeV TF versus current in MCS showingsomehysteresisatlowcurrent (note that one square is 1% variation in TF) Uncorrected b3 if hysteresisisneglected

  10. WHAT HAS BEEN DONE IN 2009:HYSTERESIS – other cases • Latticesextupoles MS • Workatverylowcurrent (6 and 10 A) • At 6 A hysteresisgives 7% difference in TF • Since one corrects 90 units … • Neglectingthisgives6 units of uncorrectedchromaticity • Properpre-cycle isneeded, and DCmagnetization has to beincluded in the FiDeLparameters (Walter remark) • Some correctors (orbit correctors, MQT, MQS, …) have no nominal settings and canworkaroundzerocurrent • Here, wedo not even know on whichbranchwe are • Orbit correctors proved to be ok ! • This effectisdeemed to be not important and isneglected for the first phases of commissioning • Case of MQT wasdiscussedwidely, additionalmeasurements in progress TF of the latticesextupole MS

  11. WHAT HAS BEEN DONE IN 2009:PENETRATION COMPONENT • Some MQM and MQY operatebelow the penetrationfield • A penetration component withtwoparametershas been added to the FiDeLequations has been proposed by W. VenturiniDelsolaro MQM transferfunction: measurements versus FiDeL fit withpenetration component

  12. WHAT HAS BEEN DONE IN 2009:PENETRATION COMPONENT • Some MQM and MQY operatebelow the penetrationfield • Wenow have a model thatfitsalsothisbehaviour • Neglectingthis component would have given non-negligible beta-beating (estimates of M. Giovannozzi) MQM transferfunction: measurements versus FiDeL fit withpenetration component

  13. WHAT HAS BEEN DONE IN 2009:DATABASE • FiDeLparameters are stored in Oracle database • Five tables: • REFPARM – all parameters, withloading date to track changes • REFPARM_2008 and REFPARM_2009 – with 2008 and 2009 values – these tables containgenerics • The genericsallowsavoidrepeatingseveral times the same data – easier for input • REFPARM_200X_EXPANDED – with all parameters, expanded – easier for having a global view • Database active in the final formsince May 2009 (L. Deniau, P. Hagen, based on the work of R. Wolf) • Easyaccess to check all parameters

  14. WHAT HAS BEEN DONE IN 2009:DOCUMENTATION • The information relative to each magnet family is given in a report • To be published as LHC Project Note • Information about: • Magnetparameters • Operationalcurrents • Availablemeasurements • Estimate of the transferfunctionparameters • Estimate of the fieldharmonicsparameters • Open issues • 250 pages of documentation are alreadyavailable on the FiDeL web site: http://www.cern.ch/fidel

  15. FUTURE ACTIVITIES AND CRITICAL POINTS • Complete the documentation • Validation LSA vs FiDeL • Correction of decay and snapback: tracking test • Pre-cycle prescriptions

  16. FUTURE ACTIVITIES: TRACKING TEST B3 • Tracking test campaigns have been carried out in 2007-2008 • B1/B2tracking test: one dipole and one quadrupolepoweredtogether – during the ramp one checks the stability of the tune, the ratio between B1 and B2 - success ! • B3tracking test: a dipolerampedwith b3 spool pieces – one integral b3measured to checks the validity of the local correction • Point of view of the beam: needed correction is 0.05 units – obtained correction: 0.3 units b3 Tracking test, dipole 2624, aperture 1 (left) and aperture 2 (right)

  17. FUTURE ACTIVITIES: TRACKING TEST B3 • Point of view of the magnet: • Injection current (geometric+persistent) about -8 units, 0.2 unitsleft (correction worksat 98% - good) • Decay: about 0.6-1 unit, 0.2 unitsleft (correction worksat 65-80%) • Snapback and after: about 0.6-1 unit, 0.4 unitsleft (correction worksat about 50% - bad) – much longer thansnapback… • During the ramp: variation of about 7 unitsreduced to 0.3 units, (correction worksat 95% - not bad) • Still a lot to understand • New tracking test in SM18 • Results in September • Empiricalway of correcting • Also important cross-check of new measuring system b3 Tracking test, dipole 2598, aperture 1

  18. FUTURE ACTIVITIES: TRACKING TEST B3 • Another relevant point: ramp rate • All SM18 measurements on MB and MQ have been doneat 50 A/s ramp rate, differentfrom nominal (10 A/s) – thereis a strong impact on decay and snapback • With 50 A/s the decay and associatedsnapbackismuchlarger (fatctortwo) • Rescaling of all measurements to operational conditions isdelicate

  19. FUTURE ACTIVITIES: PRE-CYCLES • Database of pre-cycles • R. Wolf created an Oracle DB in 2007-2008 with optimized pre-cycles based on FiDeL activities and LEP experience • LSA has an Oracle DB of pre-cycles used in the LHC sequencer: thiswasusedduring the successful 2008 run • A synchronizationbetween the twoisneededasap • For the 3.5 TeVrun • All efforts shouldbedone to reduce as much as possible the pre-cycle time (nearly 2 h for the MB in the DB of Rob) takingadvantage of the reducedenergy • MB rampwill last 550 s instead of 1000 s • Decayproportional to flatopenergy at 3.5 TeVwewill have half of the decay

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