Multiphysics modelling of the LHC main quadrupole superconducting

Multiphysics modelling of the LHC main quadrupole superconducting circuit - COSIM results presentation D. Pracht On behalf of the STEAM team Thanks a lot for your help! Thanks a lot to: Valérie Montabonnet (CERN) & Zinur Charifoulline (CERN) & Gerard Willering (CERN) Geneva, 13. -14. 06. 2019 1/18/2022 MQ – Simulation & Validation 2

Generate a model Circuit power supply, energy extraction, busbars, … PSpice COSIM Magnet coil geometry, cable parameters, iron yoke, … LEDET 1/18/2022 MQ – Simulation & Validation 3

LHC Main Quadrupole magnet Main Quadrupole: • The quadrupole magnets focus the particle beams, controlling their width and height • Nominal current 11870 A • Operating at 1. 9 K • Length: 3. 1 m • Quench protection based on quench heaters (QHs) and cold by -pass diodes 1/18/2022 MQ – Simulation & Validation 4

LHC Main Quadrupole magnet Parameters from the measurement: Itest = 11. 69 k. A LEDET and COMSOL® Parameters: - Quenching 1 cable half-turn at: tquench, HT = 0 s frac_He = 3. 5 % RRR = 100 - Quench Heaters implemented - Heat exchange between layers and poles implemented Good agreement with measurement data* * Thanks to Emmanuele for implementing all these changes in LEDET within 1 (!) day 1/18/2022 - Simplified (adiabatic) velocity of quench propagation used from the first timestep v. QP = 25 m/s MQ – Simulation & Validation 5

LHC Main Quadrupole magnet Parameters from the measurement: Itest = 11. 69 k. A LEDET and COMSOL® Parameters: - Quenching 1 cable half-turn at: tquench, HT = 0 s frac_He = 3. 5 % RRR = 100 - Quench Heaters implemented - Heat exchange between layers and poles implemented Good agreement with measurement data 1/18/2022 - Simplified (adiabatic) velocity of quench propagation used from the first timestep v. QP = 25 m/s MQ – Simulation & Validation 6

Electro-thermal model COMSOL: 2 D – temperature plot at 79 ms - Quench heaters are start to heat up the coil at 17 ms - it takes 62 ms more to see a significant temperature increase within the 2 D plot 1/18/2022 MQ – Simulation & Validation 7

Electro-thermal model COMSOL: 2 D – temperature plot at 153 ms - After 153 ms the parts without direct Quench Heater contact are heated up by the neighboring halfturns 1/18/2022 MQ – Simulation & Validation 8

Electro-thermal model COMSOL: 2 D – temperature plot at 210 ms - After 210 ms the entire coil is in normal state 1/18/2022 MQ – Simulation & Validation 9

Main quadrupole circuit The LHC main quadrupole circuit: • power converter (PC) • energy-extraction (EE) • main quadrupole magnets (MQ) and their protection system • earthing circuits (EC) • redundant system of submodules within the power converter 1/18/2022 MQ – Simulation & Validation 10

Main quadrupole circuit The LHC main quadrupole circuit: • power converter (PC) • energy-extraction (EE) • main quadrupole magnets (MQ) and their protection system • earthing circuits (EC) • 2 x 8 circuits within the LHC • within one mechanical structure two electrical magnets (RQD/RQF) in two + earthing circuit separate circuits + filters • redundant system of sub+ magnets modules within the power + energy extraction converter 1/18/2022 MQ – Simulation & Validation 11

Main quadrupole circuit – modelling Sub-sub module: • Consist of a power supply signal, two diodes in parallel, resistors and capacitances 1/18/2022 MQ – Simulation & Validation 12

Main quadrupole circuit – modelling Energy-Extraction System: • Consist of four parallel branches of switches • Parallel to the branches the energy-extraction-resistor is located • This resistor takes the whole current during the discharge and reduces the time-constant of the discharge. 1/18/2022 MQ – Simulation & Validation 13

Main quadrupole circuit – modelling All circuit elements has to be: • modelled within PSPICE Netlist • tested independently • Build-up with other parts and tested Turning off the power supply Energy-extraction “active” 1/18/2022 MQ – Simulation & Validation 14

Main quadrupole circuit – modelling All circuit elements has to be: • modelled within PSPICE Netlist • tested independently • Build-up with other parts and tested Turning off the power supply Energy-extraction “active” 1/18/2022 MQ – Simulation & Validation 15

Co-Simulation of the magnet + circuit After the magnet model and the circuit model are • generated • tested • validated Co-Simulation of the combined circuit and magnet model What is COSIM? • Framework based on cooperative simulation (co-simulation) • Common coupling interface for information exchange between several models • Advantage: • complex system is decomposed in simpler parts • These parts are simulated by domain-specific models • The algorithm ensures consistency between simulations Fig. 8: Exchanging information between two ports [8] 1/18/2022 MQ – Simulation & Validation 16

Main quadrupole circuit & magnet Good agreement with measurement data 1/18/2022 MQ – Simulation & Validation 17

Main quadrupole circuit & magnet t. FPA t. EE Good agreement with measurement data 1/18/2022 MQ – Simulation & Validation 18

Main quadrupole circuit & magnet 1/18/2022 MQ – Simulation & Validation 19

Main quadrupole circuit & magnet Closer look at the simulation results: Resistance of the quenched magnet starts developing before FPA - Magnet quenches 38 ms before the FPA - Quench heater triggering 3 ms before the FPA 1/18/2022 MQ – Simulation & Validation 20

Main quadrupole circuit & magnet t. EE t. QH tquench t. QH, trigger Closer look at the simulation results: Resistance of the quenched magnet - starts developing before FPA - tquench = -0. 038 s - t. QH, trigger = -0. 003 s - t. FPA = 0. 0 s - t. QH = 0. 045 s - t. EE = 0. 102 s t. FPA 1/18/2022 MQ – Simulation & Validation 21

Main quadrupole circuit & magnet Closer look at the simulation results: - Voltage across the diode - New model developed - Model depends on the deposited energy within the diode - Further development needed Fair agreement with measurement data 1/18/2022 MQ – Simulation & Validation 22

Main quadrupole circuit & magnet Closer look at the simulation results: - Voltage across the diode - New model developed - Model depends on the deposited energy within the diode - Further development needed tquench t. FPA t. QH Fair agreement with measurement data 1/18/2022 MQ – Simulation & Validation 23

Main quadrupole circuit & magnet Closer look at the simulation results: Temperature plot of the hot-spot and his neighbors hot-spot half-turn 2 half-turn 3 1/18/2022 MQ – Simulation & Validation 24

Thank you for your attention! 1/18/2022 MQ – Simulation & Validation 25

References [1] “Technology Department (TE), 2009 - Present”. Webpage. http: //library. cern/archives/history_CERN/internal_organisation/TE. Last visit: 20. 02. 2019, 06. 27 pm. [2] “TE-MPE Group Page (TE)”. Webpage. https: //mpe. web. cern. ch/content/structure/mpe-pe. Last visit: 20. 02. 2019, 06. 48 pm. [3] “Superconductors”. Presentation. L. Bottura. Magnè, 11. 2012. [4] “Optimization of the Electromagnetic Design of the FCC Sextupoles and Octupoles”. Article in IEEE Transactions on Applied Superconductivity PP(99): 1 -1. A. Louzguiti et. al. Geneva, 01. 2019. [5] “SIGMA Documentation”. Geneva, 08. 2018. [6] “CLIQ: A new quench protection technology for superconducting magnets”. Ph. D. Thesis. E. Ravaioli. Enschede, 2015. [7] “LHC 13 k. A-18 V LHC Main Quadrupole Circuit Power Converter”. Presentation. L. Charnay, V. Montabonnet. Geneva, 2010. [8] “STEAM Co-Sim – User manual”. Documentation. STEAM team. Geneva, 2018. [9] “Co-Simulation of Transient Effects in Superconducting Accelerator Magnets”. Ph. D thesis. M. Maciejewski, . Geneva, 2019. 1/18/2022 MQ – Simulation & Validation 26