Quench protection of SC quadrupole magnets (original) (raw)
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Quench protection of the first 4 m long prototype of the HL-LHC Nb3Sn quadrupole magnet
IEEE Transactions on Applied Superconductivity
The quadrupole magnets for the LHC upgrade to higher luminosity are jointly developed by CERN and US-LARP (LHC Accelerator Research Program). These Nb3Sn magnets will be protected against overheating after a quench by a combination of heaters bonded to the coil outer surface and CLIQ (Coupling-Loss Induced Quench) units. The first 4 meter long prototype magnet, called MQXFAP1, was tested at the Brookhaven National Laboratory in stand-alone configuration. The magnet training campaign, consisting of 18 quenches, was interrupted due to the development of a short circuit between one heater strip and the coil. During the campaign, different quench protection schemes were implemented, including heaters attached to outer and inner layers, one CLIQ unit, and the energy-extraction system. The configuration including outer-layer heaters and CLIQ achieved the fastest current discharge, hence the lowest hot-spot temperature. The electromagnetic and thermal transients after a quench were simulated with the program STEAM-LEDET and found in good agreement.
Quenching behaviour of quadrupole model magnets for the LHC inner triplets at Fermilab
IEEE Transactions on Appiled Superconductivity, 2000
Abstract|The US-LHC Accelerator Project is responsible for the design and production of inner triplet high gradient quadrupoles for installation in the LHC Interaction Region. The quadrupoles are required to deliver a nominal eld gradient of 215T m in a 70mm bore, and operate in super uid helium. As part of the magnet development program, a series of 2m model magnets have been built and tested at Fermilab, with each magnet being tested over several thermal cycles. This paper summarizes the quench performance and analysis of the model magnets tested, including quench training, and the ramp rate and temperature dependence of the magnet quench current.
Quench heater experiments on the LHC main superconducting magnets
Proc. of 7th …, 2000
In case of a quench in one of the main dipoles and quadrupoles of CERN's Large Hadron Collider (LHC), the magnet has to be protected against excessive temperatures and high voltages. In order to uniformly distribute the stored magnetic energy in the coils, heater strips installed in the magnet are fired after quench detection. Tests of different quench heater configurations were performed on various 1 m long model and 15 m long prototype dipole magnets, as well as on a 3 m long prototype quadrupole magnet. The experiments aimed at optimising the layout of the quench heater strips, minimising the complexity of the protection system and determining its redundancy. In this paper we discuss the results of the performed experiments and describe the optimised quench heater design for the LHC main magnets.
IEEE Transactions on Appiled Superconductivity, 2002
As part of the US LHC program to provide high gradient superconducting quadrupoles for the LHC interaction regions, a 5.5 meter long prototype magnet has been built and tested horizontally in a production type cryostat at Fermilab. This prototype magnet was used to validate the mechanical and magnetic design, production fabrication and assembly tooling. The first prototype magnet has met the LHC requirements of operating at 215 T/m with excellent magnetic field harmonics. This paper summarizes the test results of this magnet, including quench tests and mechanical behavior over several thermal cycles.
Quench Protection Studies for the High Luminosity LHC Nb$_3$Sn Quadrupole Magnets
IEEE Transactions on Applied Superconductivity
Achieving the targets of the High Luminosity LHC project requires the installation of new inner triplet magnet circuits for the final focusing of the particle beams on each side of the two main interaction points. Each of the four circuits will include six 150 mm aperture, 132.2 T/m gradient, Nb 3 Sn quadrupole magnets to be installed in the LHC tunnel. The recently updated circuit topology is such that the protection of each magnet can be studied from a single magnet point-of-view. To limit the hot-spot temperature and the peak voltage-to-ground, a protection system was designed that quickly and reliably transfers voluminous parts of the coil to the normal-conducting state, hence distributing more homogeneously the magnets stored energy in the windings. This system is based on two elements: quench heaters attached to the outer layers of the magnet coils and CLIQ (Coupling-Loss Induced Quench). The performance of the protection system is investigated by simulating the electromagnetic and thermal transients occurring after a quench with the program STEAM-LEDET, and by conducting dedicated experiments at the CERN and FNAL magnet test facilities. The effectiveness of the quench protection system is assessed at all representative operating current levels. Furthermore, the coils hot-spot temperature and peak voltage to ground are analyzed for various failure cases, conductor parameters, and parameter distribution among the four coils. It is concluded that the proposed design assures an effective, reliable, and fully redundant quench protection system.
Quench protection studies of short model high gradient quadrupoles
IEEE Transactions on Appiled Superconductivity, 1999
Abstract|High gradient quadrupoles HGQ being developed for the CERN Large Hadron Collider LHC interaction regions will rely on strip heaters for quench protection. Tests were performed on strip heaters in two locations on 1.9 meter model quadrupoles to study heater response times from strip heater induced quenches and quench velocities and peak temperatures from spot heater induced quenches. The results for the two heater locations are presented and compared to prediction.
Quench protection study of the updated MQXF for the LHC luminosity upgrade (HiLumi LHC)
IEEE Transactions on Applied Superconductivity, 2016
In 2023, the LHC luminosity will be increased, aiming at reaching 3000 fb-1 integrated over 10 years. In order to obtain this target, new Nb3Sn low-β quadrupoles (MQXF) have been designed for the interaction regions. These magnets present a very large aperture (150 mm, to be compared with the 70 mm of the present NbTi quadrupoles), and a very large stored energy density (120 MJ/m 3). For these reasons, quench protection is one of the most challenging aspects of the design of these magnets. In fact, protection studies of a previous design showed that the simulated hot spot temperature was very close to the maximum allowed limit of 350 K; this challenge motivated improvements in the current discharge modeling, taking into account the so-called dynamic effects on the apparent magnet inductance. Moreover, quench heaters design has been studied going into more details. In this paper, a protection study of the updated MQXF is presented, benefitting from the experience gained by studying the previous design. A study of the voltages between turns in the magnet is also presented during both normal operation and most important failure scenarios.
BEAM-INDUCED QUENCH TEST OF A LHC MAIN QUADRUPOLE
2011
Unexpected beam loss might lead to a transition of the accelerator superconducting magnet to a normal conducting state. The LHC Beam Loss Monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reaches a quenchprovoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies has been performed. The beam losses are generated by means of an orbit bump peaked in one of Main Quadrupole magnets (MQ). The analysis includes not only BLM data but also the Quench Protection System (QPS) and cryogenics data. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat.
Beam-induced quench test of LHC main quadrupole
2011
Unexpected beam loss might lead to a transition of the accelerator superconducting magnet to a normal conducting state. The LHC Beam Loss Monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reaches a quenchprovoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies has been performed. The beam losses are generated by means of an orbit bump peaked in one of Main Quadrupole magnets (MQ). The analysis includes not only BLM data but also the Quench Protection System (QPS) and cryogenics data. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat.
IEEE Transactions on Applied Superconductivity, 2014
The HiLumi program is aiming to develop and build new Nb3Sn, high-field (12 T) and large aperture (150 mm) superconducting quadrupoles, which will be inserted in the LHC interaction regions and will provide the final focusing of the beam, in the program of the luminosity upgrade. The quench protection of these magnets is one of the most challenging aspects, mainly because of the large value of the magnet inductance (160 mH for the configuration with two 8 m long magnets in series), of the large value of the stored magnetic energy density in the coils (0.12 J/mm3, a factor 2 larger than in the conventional NbTi quadrupoles) and of the use of Nb3Sn as conductor, which has never been used for large accelerator magnets. Previous works have demonstrated that a "standard" conservative analysis, assuming quench heaters only on the coils outer layer, gives high hot spot temperature, close to the design limit (350 K). In this paper, a new study of quench protection is presented. The benefic effects of large dI/dt during the discharge and other dynamic effects are discussed together with options for having a partial coverage of the inner layer by quench heaters. The analysis is validated by experimental data from R&D Nb3Sn quadrupole magnets.