Quench detection method for 2G HTS wire

We report quench test results for the 1-meter long, 120 mm aperture quadrupole magnet, HQ01, designed, fabricated and tested for the LHC Accelerator Research Program (LARP). The magnet has a design gradient of 219 T/m at 1.9 K and peak field of 15 T. Earlier tests (HQ01a, b) showed peak gradients of 152 T/m at 4.4 K but also revealed electrical insulation weaknesses that ultimately led to coil damage. Structural and electrical improvements incorporated into HQ01c magnet have assured and tracked the electrical integrity of the coils. The most recent HQ01d and HQ01e tests demonstrated gradients of 170 T/m at 4.4 K (86% of short sample critical current) with moderate training. By analyzing magnet voltage test data, quench propagation velocities and quench locations were determined. Most of the quenches tended to cluster around the pole region of the coils. Eight PC-board quench antennas were installed to better identify quench locations. We monitored longitudinal propagation of pole-turn quenches and correlated inductive responses of the quench antennas with magnet voltages. On down-ramps, the HQ magnet exhibited no quenches at rates up 150 A/s; the experimental ramp-rate dependence was analyzed using a simple 'loss model'.

Section: Fast Eventsmentioning

confidence: 99%

Quench Performance of HQ01, a 120 mm Bore LARP Quadrupole for the LHC Upgrade

Marchevsky

Ambrosio

Bingham

et al. 2012

“…Resistive voltage is the most easily attainable indication of an ignited quench. However, it might not be enough in case of a HTS coil [19]. Still, quench simulations should reveal if detectable level is attained fast enough so that damage can be forbidden.…”

Section: A Cross-check Of the Codes In Benchmark Of Nb-ti Solenoidmentioning

confidence: 99%

Benchmark of Two Quench Codes for the Protection Study of an High Field HTS Insert Dipole

Stenvall

Sorbi

Volpini

et al. 2011

Research on possibilities in long-term LHC (Large Hadron Collider) upgrade include considerations on replacing the Nb-Ti dipoles with Nb 3 Sn outserts and inserts made of some high temperature superconductor (HTS) which outperforms conventional superconductors above 20 T. Regarding to this target, the WP7.4 (Very high field insert) in project EuCARD is to construct about 1 m long HTS dipole producing 6 T in background field of 13 T. Since the quench analysis of HTS coils is challenging, e.g., due to slow propagation velocities and possibly ambiguous limit between the normal and superconducting state, two different strategies are developed in parallel to analyse the quench of the small prototype insert. The one is based on propagation velocities and the other on solving heat diffusion equation with finite element method. The very first steps of the development include benchmark calculations with the already existing programs for small Nb-Ti solenoid to guarantee similar starting points for the partners. After this, a quench analysis was performed for an HTS solenoid. In this paper we consider the results of these calculations.

“…To shorten the initial cooling time and promptly remove the HTS magnet's hot spot by quenching, the thermal conductivity of the HTS magnet should be high. With the remarkable growth of second-generation (2G) HTS wire, studies on 2G HTS magnets wound by this wire have actively progressed [1]- [4].…”

Section: Introductionmentioning

confidence: 99%

Thermal Characteristics of 2G HTS Tape With Anodized Aluminum Stabilizer for Cryogen-Free 2G HTS Magnet

Bae

Jeong

2015

Studies on second-generation (2G) high temperature superconductor (HTS) magnets cooled by a cryogenic refrigerator are actively underway due to the recent rapid advancement in 2G HTS tape technology. To reduce the initial cooling time, lower the operating temperature, and promptly extract the hot spot of the conduction cooled 2G HTS magnet during quenching, the magnet's equivalent thermal conductivity should be high. In general, conventional 2G HTS tapes use a copper stabilizer wrapped with a low thermal conductivity polyimide electrical insulation tape. Ultimately, the low thermal conductivity of these conventional HTS magnets lengthens the cooling time, causing the magnet to burn out during quenching. In this paper, by replacing the copper stabilizer with an aluminum stabilizer and anodizing it for electrical insulation instead of using polyimide tape, the 2G HTS tape's equivalent thermal conductivity was largely improved. Based on the results of thermal analysis and tests, the thermal characteristics of a conventional 2G HTS tape are compared with those of the 2G HTS tape presented in this paper.