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Fiscarelli, L.

Paper Title Page
MOOCRA01 The Magnetic Model of the LHC in the Early Phase of Beam Commissioning 55
 
  • E. Todesco, N. Aquilina, B. Auchmann, L. Bottura, M.C.L. Buzio, R. Chritin, G. Deferne, L. Deniau, L. Fiscarelli, J. Garcia Perez, M. Giovannozzi, P. Hagen, M. Lamont, G. Montenero, G.J. Müller, S. Redaelli, RV. Remondino, F. Schmidt, R.J. Steinhagen, M. Strzelczyk, M. Terra Pinheiro Fernandes Pereira, R. Tomás, W. Venturini Delsolaro, J. Wenninger, R. Wolf
    CERN, Geneva
  • N.J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
 

The re­la­tion be­tween field and cur­rent in each fam­i­ly of the Large Hadron Col­lid­er mag­nets is mod­eled with a set of em­pir­i­cal equa­tions (FiDeL) whose free pa­ram­e­ters are fit­ted on mag­net­ic mea­sure­ments. They take into ac­count of resid­u­al mag­ne­ti­za­tion, per­sis­tent cur­rents, hys­tere­sis, sat­u­ra­tion, decay and snap­back dur­ing ini­tial part of the ramp. Here we give a first sum­ma­ry of the re­con­struc­tion of the mag­net­ic field prop­er­ties based on the beam ob­serv­ables (orbit, tune, cou­pling, chro­matic­i­ty) and a com­par­i­son with the ex­pec­ta­tions based on the large set of mag­net­ic mea­sure­ments car­ried out dur­ing the 5-years-long pro­duc­tion. The most crit­i­cal is­sues for the ma­chine per­for­mance in terms of knowl­edge of the re­la­tion mag­net­ic field vs cur­rent are pinned out.

  

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Slides

 
MOPEB018 Measurement and Scaling Laws of the Sextupolar Component in the LHC Dipole Magnets 316
 
  • M.C.L. Buzio, L. Bottura, O. Dunkel, L. Fiscarelli, J. Garcia Perez, G. Montenero, E. Todesco, L. Walckiers
    CERN, Geneva
  • P. Arpaia
    U. Sannio, Benevento
  
 

One of the main re­quire­ments for the op­er­a­tion of the Large Hadron Col­lid­er at CERN is the cor­rec­tion of the dy­nam­ic mul­ti­pole er­rors pro­duced in the main mag­nets*. In par­tic­u­lar, in­te­grat­ed sex­tupole er­rors in the main dipoles must be kept well below 0.1 units to en­sure ac­cept­able chro­matic­i­ty. The feed-for­ward con­trol of the LHC is based on the Field De­scrip­tion for the LHC (FiDel), a se­mi-em­pir­i­cal math­e­mat­i­cal model ca­pa­ble of fore­cast­ing the mag­net's be­haviour in order to gen­er­ate suit­able cor­rec­tor cur­rent wave­forms. Mea­sure­ment cam­paigns were re­cent­ly un­der­tak­en to val­i­date the model mak­ing use of a novel fast ro­tat­ing-coil mag­net­ic mea­sure­ment sys­tem (FAME)**, able to de­tect su­per­con­duc­tor decay and snap­back tran­sients with un­prece­dent­ed ac­cu­ra­cy and tem­po­ral res­o­lu­tion. In this paper we dis­cuss the test setup and the re­sults ob­tained both on the test bench and in the ac­tu­al op­er­a­tion of the ac­cel­er­a­tor.


* P. Xydi et al, "A Demonstration Experiment For The Forecast Of Magnetic Field … ", EPAC 2008
** N. R. Brooks et al, "Estimation Of Mechanical Vibration Of …", IEEE TAS 2008