Abstract
Abstract. The High-Luminosity upgrade project for the Large Hadron Collider (HL-LHC) at CERN (Conseil Européen pour la Recherche Nucléaire) will require new superconducting magnets for the insertion regions. Among these magnets, the new triplet quadrupoles, based on Nb3Sn technology, require magnetic-field measurements of a high precision in the field angle and multipole field errors. In this paper, we present a scanning system based on a rotating-coil magnetometer and its transport system, including the design of the mechanical structure and the induction coils based on printed-circuit-board (PCB) technology. The system and its components are cross-calibrated with other field transducers, such as stretched-wire systems, and their measurement precision is established in a measurement campaign of 2 m long reference quadrupoles.
Highlights
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) (Apollinari et al, 2017) requires replacing the superconducting magnets in the insertion regions
We present a scanning system based on a rotating-coil magnetometer and its transport system, including the design of the mechanical structure and the induction coils based on printed-circuit-board (PCB) technology
The expected accuracy for the field harmonics are based on the probes developed by the Fermi National Accelerator Laboratory (FNAL) and Lawrence Berkeley National Laboratory (LBNL) for the LHC Accelerator Research Program (LARP) described in DiMarco et al (2013)
Summary
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) (Apollinari et al, 2017) requires replacing the superconducting magnets in the insertion regions. The magnets must be measured with even more stringent requirements with respect to the state of the art, both locally and integrated over their entire length of up to 10 m To meet these requirements, the superconducting quadrupole magnets have to be measured using both rotating-coil magnetometers (Davies, 1992) and stretchedwire systems (DiMarco et al, 2000). The voltage between two triggers is integrated, yielding a measure of the incremental flux linkage between the two rotor positions This corresponds to a reparametrization of the signal with respect to the rotation angle. In the case of a centered quadrupole measurement, the dipole component will vanish, except if the coil is decentered with respect to the magnetic axis This misalignment can be calculated and corrected by translating the reference frame of the sensor to the magnet axis. This yields the centered field harmonic coefficients as well as the position of the magnetic field center in the local sensor coordinates
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