Power Test of the First Two HL-LHC Insertion Quadrupole Magnets Built at CERN

Abstract

The High-Luminosity project (HL-LHC) of the CERN Large Hadron Collider (LHC), requires low β* quadrupole magnets in Nb 3 Sn technology that will be installed on each side of the ATLAS and CMS experiments. After a successful short-model magnet manufacture and test campaign, the project has advanced with the production, assembly, and test of fullsize 7.15-m-long magnets. In the last two years, two CERN-built prototypes (MQXFBP1 and MQXFBP2) have been tested and magnetically measured at the CERN SM18 test facility. These are the longest accelerator magnets based on Nb 3 Sn technology built and tested to date. In this paper, we present the test and analysis results of these two magnets, with emphasis on quenches and training, voltage-current measurements and the quench localization with voltage taps and a new quench antenna.

Modelling V-I Measurements of Nb3Sn Accelerator Magnets With Conductor Degradation

“…8. The voltage of two internal segments of a coil of the MQXFBP1 quadrupole magnet is shown here for a staircase-type V-I measurement [4]. At the final 14 kA plateau we observe a positive decaying voltage in one segment and a negative decaying voltage in another segment, which is highly unusual after ramp up.…”

“…8. Experimental V-I data of the MQXFBP01 prototype quadrupole magnet [4]. At the 14 kA plateau a positive decaying voltage appears in section 3126-3127 and a negative decaying voltage appears in section 3127-3118. strands 1 and 16 fully degraded, strands 2 and 15 are 98% degraded, and strands 3 and 14 are 96% degraded.…”

“…I N THE last few years, new 11 T dipole and MQXF quadrupole magnets for the HL-LHC [1]- [4] have been tested at the SM18 test facility at CERN. An important tool for assessing magnet performance is the V-I (voltage-current) measurement.…”

Status of the MQXFB Nb3Sn Quadrupoles for the HL-LHC

“…A 2 kA DC power converter was connected using the CLIQ lead [10] to allow powering the magnet with reduced current in coil 113 (P1). Two out of the other three coils were limited at 500-600 A higher than the limiting coil 113 [9]. At 1.9 K with a ramp of 1 A/s, coils 110, 111 and 112 reached 17 kA without quench.…”

“…All quenches except those at the highest ramp rate were in the same coil, both at 1.9 K and 4.5 K. In all the cases, the quench starts in the inner layer pole turn. The longitudinal position of the quench in-itiation was derived from the quench antenna signals, and it was in all the cases close to the magnet mechanical center [9].…”