| Paper |
Title |
Page |
| WEPCH139 |
WISE: An Adaptative Simulation of the LHC Optics
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2248 |
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- P. Hagen, M. Giovannozzi, J.-P. Koutchouk, T. Risselada, S. Sanfilippo, E. Todesco, E.Y. Wildner
CERN, Geneva
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The LHC beam dynamics requires a tight control of the magnet field quality and geometry. As the production of the magnets advances, decisions have to be made on the acceptance of possible imperfections. To ease decision making, an adaptative model of the LHC optics has been built, based on the current information available (e.g. magnetic measurements at warm or cold, magnet allocation to machine slots) as well as on statistical evaluations for the missing information (e.g. magnets yet to be built, measured, or for non-allocated slots). The uncertainties are included: relative and absolute measurement errors, warm-to-cold correlations for the fraction of magnets not measured at cold, hysteresis and power supply accuracy. A pre-processor generates instances of the LHC ring for the MADX program, with the possibility of selecting various error sources. A post-processor computes ranges for relevant beam optics parameters and distributions. This approach has been applied to the expected beta-beating, to the possible impact of permeability issues in some quadrupole collars, to the geometrical displacements of the multipolar correctors and to prioritize the magnetic measurement programme.
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| WEPLS103 |
The Field Description Model for the LHC Quadrupole Superconducting Magnets
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2619 |
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- N.J. Sammut, L. Bottura, S. Sanfilippo
CERN, Geneva
- J. Micallef
University of Malta, Faculty of Engineering, Msida
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The LHC control system requires an accurate forecast of the magnetic field and the multipole field errors to reduce the burden on the beam-based feed-back. The Field Description for the LHC (FIDEL) is the core of this forecast system and is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet apertures. The effects are quantified using the data obtained from series magnetic measurements at CERN and they are consequently modelled empirically or theoretically depending on the complexity of the physical phenomena. This paper presents a description of the methodology used to model the field of the LHC magnets particularly focusing on the results obtained for the LHC Quadrupoles (MQ, MQM and MQY).
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| WEPLS104 |
The Dependence of the Field Decay on the Powering History of the LHC Superconducting Dipole Magnets
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2622 |
| |
- N.J. Sammut, L. Bottura, S. Sanfilippo
CERN, Geneva
- J. Micallef
University of Malta, Faculty of Engineering, Msida
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The decay amplitude of the allowed multipoles in the LHC dipoles is expected to perturb the beam stability during the injection phase and is strongly dependent on the powering history of the magnet. The effect is particularly large for the pre-cycle nominal flat-top current and duration. With possible prospects of having different genres of cycles during the LHC operation, the powering history effect must be taken into account in the Field Description Model for the LHC (FIDEL) and must hence be corrected for during machine operation. This paper presents the results of the modelling of this phenomenon. We also discuss the statistic of magnetic measurements required to guarantee that the current history effect is predicted within the specified accuracy.
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| WEPLS105 |
Performance of the LHC Arc Superconducting Quadrupoles towards the End of their Series Fabrication
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2625 |
| |
- T. Tortschanoff, P. Hagen, M. Modena, L. Rossi, S. Sanfilippo, K. M. Schirm, E. Todesco, E.Y. Wildner
CERN, Geneva
- R. Burgmer, H.-U. Klein, D. Krischel, B. Schellong, P. Schmidt
ACCEL, Bergisch Gladbach
- M. Durante, A. Payn, F. Simon
CEA, Gif-sur-Yvette
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The fabrication of the 408 main arc quadrupole magnets and their cold masses will come to an end in summer 2006. A rich collection of measurement and test data has been accumulated and their analysis is presented in this paper. These data cover the fabrication and the efficiency in the use of the main components, the geometrical measurements and the achieved dimensional precision, the warm magnetic measurements in the factory and the performance at cold conditions, especially the training behaviour. The scrap rate of the NbTi/Cu conductor as well as that of other components turned out to be acceptably low and the quench performance measured was in general very good. Most quadrupoles measured so far exceeded the operating field gradient with one or no quench. The multipole content at cold was measured for a limited numbers of quadrupoles as far as needed for verifying the warm-to-cold correlation. From the point of view of field quality, all quadrupoles could be accepted for the machine and the measures taken to overcome the problem of a too high permeability of a batch of collars are discussed.
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| WEPLS100 |
Performance of LHC Main Dipoles for Beam Operation
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2610 |
| |
- G. De Rijk, M. Bajko, L. Bottura, M.C.L. Buzio, V. Chohan, L. Deniau, P. Fessia, J. Garcia Perez, P. Hagen, J.-P. Koutchouk, J. Kozak, J. Miles, M. Missiaen, M. Modena, P. Pugnat, V. Remondino, L. Rossi, S. Sanfilippo, F. Savary, A.P. Siemko, N. Smirnov, A. Stafiniak, E. Todesco, D. Tommasini, J. Vlogaert, C. Vollinger, L. Walckiers, E.Y. Wildner
CERN, Geneva
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At present about 75% of the main dipoles for the LHC have been manufactured and one of the three cold mass assemblers has already completed the production. More than two third of the 1232 dipoles needed for the tunnel have been tested and accepted. In this paper we mainly deal with the performance results: the quench behavior, the magnetic field quality, the electrical integrity quality and the geometry features will be summarized. The variations in performance associated with different cold mass assemblers and superconducting cable origins will be discussed.
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