Magnet Transfer Function Measurements M Guinchard Mechanical Measurement

Magnet Transfer Function Measurements M. Guinchard- Mechanical Measurement Laboratory H 0 (ω) 12/29/2021

Outline 1. Introduction to Experimental Modal Analysis (EMA) 2. Previous measurements 3. Measurement in practice 4. HL-LHC String Measurements 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 2

Experimental Modal Analysis (EMA) • A technique to evaluate the modal characteristics of a structure • Natural frequencies • Damping • Mode shapes • Why to use the experimental modal analysis? • Anticipate problems related to vibrations • Support to failure analysis • Verification of FEA-models At CERN the technique is particularly important due to the high sensitivity and/or fragility of CERN structures like detectors or magnets. 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 3

Time Output Input Acceleration Force [N] Experimental Modal Analysis (EMA) F F T Time Acceleration Force [N] F F T Frequency I(ω) Frequency O(ω) H(ω) 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 4

Previous measurements Q 1 spare magnet installed in stand alone at SM 18 (HL-LHC Civil Engineering Study) CM-Q 2 CM-IP Jack-IP H 0 (ω) Jack-Q 2 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 5

Previous measurements Q 1 spare magnet installed in stand alone at SM 18 (HL-LHC Civil Engineering Study) Vertical Lateral 21. 5 Hz 8. 4 Hz H 0 (ω) 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 6

Previous measurements MQXA Cold mass (FEA benchmark for HL-LHC) Vertical Modes 1 st 2 nd 65. 9 Hz 23. 5 Hz Lateral Modes 1 st 2 nd 25. 7 Hz 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 63. 4 Hz 7

Why to perform these measurements? The first bending mode of LHC triplet magnets (around 22 Hz) can be easily excited… And we need to anticipate the situation for HL-LHC !!! - HL-LHC Civil engineering study ; Vibrator truck excitation @22 Hz on ATLAS parking ; LHC beam oscillation clearly visible ! - HL-LHC Civil engineering activities ; Compaction of the shaft platform – Compactor excitation around 25 Hz ; LHC beam oscillation clearly visible ! Courtesy of M. Schaumann Injection optics R 2015 a_A 11 C 11 A 10 L 10, Courtesy of Jorg Wenninger 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 8

HL-LHC String Measurements Goal of the measurements : Determine experimentally the transfer functions (TF) between the floor (close to the jacks) and the cold mass for several magnets in different configurations : - Standalone magnet → FEA Benchmark. - Magnet interconnected → Effect of additional stiffness needs to be evaluated, considered as negligible today; - Magnet at cold temperature → Effect of additional cryogenic liquid mass needs to be evaluated; Boundary conditions : Measurements must be done with the real supporting conditions as the supports (jacks), fixations on the floor and load repartitions between supports ! The supporting conditions must stay for the overall measurement process ! 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 9 H 0 (ω)

HL-LHC String Measurements Measurement methods : - Standalone magnet → As for Q 1 spare magnet with hammer excitation; - Magnet interconnected → Floor excitation and the cold mass response will be measured on the floor – No instrumentation inside the magnet - Magnet at cold temperature → Floor excitation and the cold mass response will be measured on the floor – No instrumentation inside the magnet Schedule : The activity is forecaste for 2022 with the following duration: - Standalone magnet → Expected duration for installation and measurements : 3 Days per magnet. Magnet interconnected → Expected duration for installation and measurements : 1 Day per magnet. Magnet at cold temperature → Expected duration for installation and measurements : 1 Day per magnet Analysis and reporting : 3 days per magnet 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard 10

Discussion / Questions 12/29/2021 Magnet Transfer Function Measurements - M. Guinchard