Loss and dynamic magnetic field measurements in LHC dipoles

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Abstract-We report the main results of the magnetic field measurements performed on the full-size LHC superconducting dipoles tested at CERN since summer 1998. Main field strength and field errors are summarized. We discuss in detail the contributions related to the geometry of the collared coil, the assembled cold mass, cool-down effects, magnetization of the superconducting cable and saturation effects at high field. Dynamic effects on field harmonics, such as the field decay during injection and field errors during current ramps, are assessed statistically.

Section: B Eddy Currentsmentioning

confidence: 59%

Measurement and analysis of the field quality of LHC prototype and pre-series superconducting dipoles

Aleksa

Amet

Ang

et al. 2002

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“…Results show significant improvements in this respect as compared to the second generation of prototype magnets, thanks to the strand coating (SnAg ) and oxidation process developed at CERN for the third generation prototypes, pre-series, and series magnets [12]. The control of the contact resistances between strands of the cable is also confirmed by loss measurements, ramp rate effect on the field quality [13] and by the amplitude of the periodic field modulation measured inside apertures of the third generation prototypes and first pre-series dipoles [14].…”

Section: Quench Sensitivity To the Ramp Ratementioning

confidence: 70%

Performance of the LHC final prototype and first pre-series superconducting dipole magnets

Bottura

D'Angelo

Gateau

et al. 2002

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Abstract-Within the LHC cryo-dipole program, six full-scale superconducting prototypes of final design were built in collaboration between Industry and CERN, followed by launching the manufacture of pre-series magnets. Five prototypes and the first of the pre-series magnets were tested at CERN. This paper reviews the main features and the performance of the cryo-dipoles tested at 4.2 K and 1.8 K. The results of the quench training, conductor performance, magnet protection, sensitivity to ramp rate and field characteristics are presented and discussed in terms of the design parameters.

“…For long dipoles, the so-called "Field-Advance" produced by eddy-current was also measured with Hall probes during current cycles optimized for this study [13]. The values of the cross-contact resistance deduced from such measurements are also reported in Table IV.…”

Section: Study Of the Pfp Inside Long And Short Dipolesmentioning

confidence: 99%

Investigation of the periodic magnetic field modulation in LHC superconducting dipoles

Pugnat

Schreiner

Siemko

2002

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Abstract-The windings of high-field accelerator magnets are usually made of Rutherford-type superconducting cables. The magnetic field distribution along the axis of such magnets exhibits a periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. This effect, resulting from quasipersistent currents, was investigated with a Hall probes array inserted inside the aperture of the LHC superconducting dipoles, both in short models and full-scale prototypes. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the magnet current history. The origin and the impact on the LHC dipoles stability of the nonuniform current redistribution producing such a field modulation are discussed.Index Terms-LHC, periodic field pattern, persistent eddy-current, quench performance, Rutherford type cable, superconducting magnets.