Review of Quench Performance of LHC Main Superconducting Magnets

Abstract

Abstract-The regular lattice of the Large Hadron Collider (LHC) will make use of more than 1600 main magnets and about 7600 corrector magnets, all superconducting and working in pressurized superfluid helium bath. This complex magnet system will fill more than 20 km of the LHC underground tunnel. In this paper an overview of the cold test program and quality assurance plan to qualify all LHC superconducting magnets will be presented. The quench training performance of more than 1100 LHC main dipoles and about 300 main quadrupoles, cold tested to date, will be reviewed. From these results an estimate of the number of quenches that will be required to start operation of the whole machine at nominal energy will be discussed. The energy level at which the machine could be operated at the early phase of the commissioning without being disturbed by training quenches will be addressed. The LHC magnet program required the development of many new tools and techniques for the testing of superconducting magnet coils, magnet protection systems, cryogenics, and instrumentation. This paper will also present a summary of this development work and the results achieved.Index Terms-Cryogenic test station, LHC, memory effect after thermal cycle, superconducting magnets, training quench.

Retraining of the 1232 Main Dipole Magnets in the LHC

“…During the reception tests in 2002-2007 all magnets were individually cooled down to 1.9 K and ramped up with 10 A/s until a quench would occur, or until 12850 A was reached. Due to time constraints, the training of about half of the magnets was stopped between 12000 A and 12850 A [12]. In total 1115 quenches were needed to train to the nominal current of 11850 A; see Table III.…”

Performance Evaluation and Quality Assurance Management During the Series Power Tests of LHC Main Lattice Magnets

“…Around 90% of the electrical NC of Table I was discovered during the cold tests or preparatory phases on the test benches. The cold tests allowed separating out magnets that would otherwise compromise the accelerator performance and permitted its projection [22].…”

“…To reach the LHC nominal energy level of 7 TeV will imply to cope with training quenches of MBs, MQs as well as of other superconducting magnets. The expected quench performance of the main dipoles and the main quadrupoles during their first powering cycles in the LHC machine is discussed in details in [22].…”

Magnetic Performance of the Main Superconducting Magnets for the LHC

“…The machine is expected to start exploitation by mid 2008 [1]. The 1232 main bending dipoles (MB), the 392 main quadrupoles (MQ) and the 82 powered individually matching section quadrupoles (MQM, MQY) were tested for final acceptance at cryogenic temperature (1.9 K or 4.55 K) in the CERN Superconducting Magnet Test Plant [2]. The series tests started in June 2001 and were completed in February 2007.…”