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We report quench test results for the 1-meter long, 120 mm aperture Nb3Sn 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 \sim15 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’. [ABSTRACT FROM PUBLISHER]

As part of the effort towards the development of Nb3Sn magnets for future LHC luminosity upgrades, the LHC Accelerator Research Program (LARP) has fabricated and tested the quadrupole magnet LQS01. The magnet implements 3.4 m long Nb3Sn coils contained in a support structure characterized by an external aluminum shell segmented in four sections. The room temperature pre-load of the structure is obtained by shimming load keys through bladders, pressurized during the loading operations and removed before cool-down. Temperature compensated strain gauges, mounted on structure components and coil poles, monitor the magnet's mechanical behavior during assembly, cool-down and, excitation. During the first test, LQS01 reached the target gradient of 200 T/m; the gauge data indicated that the aluminum shell was pre-tensioned to the target value estimated by numerical models, but a lack of pre-load was measured in the coil inner layer during ramping. As a result, the test was interrupted and the magnet disassembled, and inspected. A second test (LQS01b) was then carried out following a re-loading of the magnet. The paper reports on the strain gauge results of the first test and the analysis performed to identify corrective actions to improve the coil pre-stress distribution. The mechanical performance of the magnet during the second cool-down and test is then presented and discussed. [ABSTRACT FROM AUTHOR]

In support of the luminosity upgrade of the Large Hadron Collider (LHC), the US LHC Accelerator Research Program (LARP) has been developing a 1-meter long, 120 mm bore Nb3Sn IR quadrupole magnet (HQ). With a short sample gradient of 219 T/m at 1.9 K and a conductor peak field of 15 T, the magnet will operate under higher forces and stored-energy levels than that of any previous LARP magnet models. In addition, HQ has been designed to incorporate accelerator quality features such as precise coil alignment and adequate cooling. The first 6 coils (out of the 8 fabricated so far) have been assembled and used in two separate tests—HQ01a and HQ01b. This paper presents design parameters, summary of the assemblies, the mechanical behavior as well as the performance of HQ01a and HQ01b. [ABSTRACT FROM AUTHOR]