Characterization of a Measurement System for Dynamic Effects in Large-Aperture SC Quadrupole Magnets

Abstract A new measurement system, based on a large-diameter search-coil rotating in the superfluid helium, a fast digital integrator, a motor drive unit with slip rings, and a flexible software environment was developed at CERN for the measurement of dynamic effects in superconducting magnets. This system has made it possible the measure, with a resolution of up to 1 Hz, the multipole field errors due to superconductor magnetization and interstrand coupling currents. In this paper we present the development and calibration of the measurement system, its installation in the vertical cryostat of CERN’s recently refurbished test station, and its application to the US-LARP built, 120-mm aperture Nb 3 Sn quadrupole magnet (HQ01e) for the upgrade of the LHC insertion regions. THE FAME MEASUREMENT SYSTEM The system used for the magnetic measurements of the 120-mm-aperture Nb 3 Sn quadrupole magnet (HQ01e) [3] is based on the FAME (FAst Measurement Equipment) system developed at CERN [2]. The system was adapted for the vertical test cryostat and equipped with a purpose-built, large-diameter search coil. The FAME system is composed furthermore of a GPS timing board (NI-6682), a motor drive (Micro Rotating Unit), a custom encoder board, ten Fast Digital Integrators, and a computer with a data acquisition software (FFMM).