Recommissioning of sector 12 after a short warm-up during eYETS 2016/17 QBT, MP3 – May 2017 S. Le Naour

RB.A12 : List of NCR 1775466 : LHC-QN-ELQA-TP4-E-HVQ-RB.A12-Line5-001 EDMS 1783555 : LHC-QN-ELQA-MIC-C-MBBR2359-A11L2-001

RB.A12 : List of NCR (no n°) A31L2 : Heater discharge reference EE in RR17 : problem with EE power connector on one fast opening system

RB.A12 Two training quenches to recover 11080A (@10934 A and 11055 A) versus 7 during HWC 2014/15. These 2 magnets never quenched in LHC 2313 (C28R1): Quenched at 8954,10340, 11940, 12755 A in SM18 1368 (A25R1) : Quenched at 12343,12433,12683 A in SM18 Graph and tables prepared by G. Willering

RB.A12 During the second training quench on A25R1, multiple quenches were propagated in the first second to two neighbouring magnets by iQPS system (dVQS0/dt ~ 1V/s) C25R1 B25R1 A25R1 268ms 190ms (1368) (2407) (2380)

RQF/RQD. A12 and RQX RQF/RQD.A12 Smooth re-commissioning of these 2 circuits. Minor issue with the ringing of the micro-switch ST-OPEN-A2  use as is No training quench to reach 10350A on RQD.A12 and 10580A on RQF.A12. RQX Smooth re-commissioning of the triplets No training quench to declare (neither in S12 after thermal cycle nor in other sectors)

IPQ with MQM magnets @4.5K (only S12)

IPQ (all sectors) IPQ with MQY magnets @4.5K (18 units) IPQ with MQM magnets @1.9K (46 units)

List of NCR : Arc 12 EDMS 1786862 : LHC-QN-ELQA-TP4-E-HVQ-RSD1.A12B1-001 EDMS 1786861 : LHC-QN-ELQA-TP4-E-HVQ-RQTF.A12B2-001 EDMS 1792424 : LHC-QN-ELQA-TP4E-HVQ-RQSX3.R1-001

600A circuits of the arcs Statistics on quenches from 600A magnets During HWC 16/17, most of circuits with MQT magnets quenched. Six circuits are from sector 12 and seven circuits from other sectors. Most of them are in RQTD/F circuits (8 magnets in series). All of them reached their nominal current.

RCBX performance in R1 First individually powered up to 550A, RCBX nested magnets are then powered following the rule I_RCBX2+I_RCBH2= Radius2,

RCBX performance in R1

RCBX performance in L2

RCBX performance After the warm up of the sector 12, triplet magnets included, a complete HWC was performed on all circuits. Main triplet magnets recovered there previous performance without quenching while all RCBX circuits in R1 needed some training. RCBX circuits in L2 reached their previous performance without quenching Because some detraining was observed for RCBXH1.R1 and RCBXH3.R1 during HWC 2017 and because these circuits are not used above 250 A in operation, the HWC current was limited to 410 A individually. The combined powering of RCBXH/V1.R1 needed also some training and reached 410 A (or 290*√2 A). All the other circuits passed this test without quenching. The warm up of the sector 12 seems to affect the qualification of the corrector magnets in the triplet in R1, but was transparent for L2. In the other sectors, RCBX circuits were powered only individually during the HWC campaign and no quench was declared. Reminder : on the base line of the next YETS, triplets in point 5 will be warmed up for alignment with CMS.

Summary Following the warm-up of sector 12, one Vtap of dipole A11L2 was found open, other non conformities were on warm parts of the circuits. Two training quenches occurred in RB.A12 to recover the performances to 6.5TeV. The second training quench propagated multiple quenches in the first second (electromagnetic coupling phenomena) No training quench for main triplet magnets, RQF/RQD.A12 or IPDs For IPQs and 600A, few training quenches to recover their performance but equivalent behaviour than after LS1. Unexpected behaviour of MCBX magnets in R1 only. One to five quenches occurred in each of the 6 MCBX magnets to reach 550A individually. As they are not powered more than 250A in operation, the commissioning was stopped at 410 A for 2 circuits. MCBX magnets in L2 reached the nominal current without quenching.

List of NCR EDMS 1772023 : LHC-QN-ELQA-TP4E-HVQ-RB.A78.Line#6-001 EDMS 1798903 : QN-ELQA-MIC-C-IRC-MQ.23R3.001 EDMS 1798908 : QN-ELQA-MIC-C-IRC-MQ.28L4.001 EDMS 1803495 : LHC-QN-ELQA-TP4E-HVQ-RCO.A78B2-001