| Paper |
Title |
Page |
| WEPLS103 |
The Field Description Model for the LHC Quadrupole Superconducting Magnets
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2619 |
| |
- 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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| WEPCH048 |
Measurement and Modeling of Magnetic Hysteresis in the LHC Superconducting Correctors
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2026 |
| |
- W. Venturini Delsolaro, L. Bottura, Y. C. Chaudhari, M. Karppinen
CERN, Geneva
- N.J. Sammut
University of Malta, Faculty of Engineering, Msida
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The Large Hadron Collider, now under construction at CERN, relies heavily on superconducting magnets for its optics layout: besides the main magnets, almost all the correcting magnets are superconducting. Along with clear advantages, this brings about complications due to the effects of persistent currents in the superconducting filaments. Correcting magnets that trim key beam parameters or compensate field errors of the main magnets (among others those due to hysteresis), are in their turn hysteretic. The measured magnetic hysteresis and its possible influence on accelerator operation will be presented, in particular the real-time compensation of decay and snapback in the main magnets, and the reproducibility between runs. A detailed characterization of minor hysteresis loops is given, as well as degaussing cycles and modeling work.
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