Cooldown and warmup cycles in MQXFS tests at

Cool-down and warm-up cycles in MQXFS tests at FNAL Stoyan Stoynev /FNAL/ Technical meeting on cool-down and warm-up during test 28 August 2019

MQXFS 1 at FNAL q MQXFS 1 - the first 150 mm aperture, 1. 5 m long Nb 3 Sn quadrupole within the CERN and LARP collaboration ü q 2016 2017 2018 Coils fabricated by CERN (#103 and #104) and LARP (#3 and #5) Five tests performed since 2016 MQXFS 1 a: Training, mag. measurements, PH tests, energy extraction tests ü MQXFS 1 b: (increased azimuthal pre-stress) Training, mag. measurements, CLIQ and heater tests ü MQXFS 1 c: (increased axial pre-stress) Training, mag. measurements, CLIQ and heater tests ü MQXFS 1 d: (welded SS shell test ) Training, mag. measurements ü MQXFS 1 e: (Through busbar test) Magnet training, mag. measurements, busbar spot heater tests ü Further extensive hipot tests with thermal cycles were conducted but the magnet was never powered MQXFS 1 d test preparations 2

MQXFS 1 training history SSL@1. 9 K is 21 500 A SSL@4. 3 K is 19 550 A 2016 TC TC 130 K 20 40 60 WU 30 K TC 80 Stainless steel welded Each color represents (naturally) also a thermal cycle 2018 2017 2016 100 20 k. A 14 k. A Busbar test Increased axial pre-stress Increased azimuthal pre-stress 3

MQXFS 1 quench/trip history q 119 spontaneous quenches q 230 provoked quenches and trips (above or equal to 1 k. A) q 48 unintended trips (above or equal to 1 k. A) q Total of 7 full thermal cycles, one partial (130 K) and a warm up to 30 K (not counting the ones for the hi-potting tests where the magnet was not powered) Training history (20 A/s ramps) TC WU 30 K TC 130 K TC (each test by itself) Note also the remarkably stable performance at 4. 5 K (after /re/training; the level is ~95% SSL) 4

MQXFS 1 a cool-down WARM-UP 5

MQXFS 1 b cool-down WARM-UP 6