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Quench protection of the MCBXFA and MCBXFB orbit correctors

This presentation discusses the magnet and conductor specifications, possible quench protection strategies, and simulation results for the MCBXF orbit correctors, along with sensitivity analysis for heat transfer coefficients.

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Quench protection of the MCBXFA and MCBXFB orbit correctors

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  1. Quench protection of the MCBXFA and MCBXFB orbit correctors Alejandro Fernandez Navarro andFernando Toral (CIEMAT) 13th February 2019

  2. Outline • Magnet and conductor specifications • Possible quench protection strategies • Electro-thermal models for quench simulation • Simulation results • Sensitivity analysis for heat transfer coefficients • Conclusions

  3. Magnet and conductor specifications

  4. Possible quench protection strategies Inner Dipole Preferred protection strategies Outer Dipole

  5. Electro-thermal models for quench simulation • Modeled and simulatedeachdipolemagnetindependently (inners/Outers). Conservativeassumption. • Modeledboth transversal and longitudinal quenchpropagation. • Cables adiabatictothe He bath (fiberglassimpregnated cables). • Quenchdetectionvoltage: 100 mV. Minimumquenchdetection time: 20 ms. Quenchvalidation time: 10 ms. • Initialquench in the pole turn conductor (highestfield). SQUID ROXIE • CERN in-housecode. BEM-FEM. • Calculatedvoltagetoground. • CIEMAT in-housecode in Matlablanguage. Finitedifferencesmethod. • Calculatedvoltageistheresistivevoltage (higherthanvoltagetoground).

  6. Simulation resultsMCBXFB (short magnet) Inner Dipole Outer Dipole *SQUID: resistivevoltage. ROXIE: voltagetoground. Estimatedultimatecurrentswith ROXIE 2D. Present protection baseline

  7. Simulation resultsMCBXFA (long magnet) Inner Dipole Outer Dipole ? *SQUID: resistivevoltage. ROXIE: voltagetoground. Estimatedultimatecurrentswith ROXIE 2D. Present protection baseline

  8. Differences in results • A difference in thequenchpropagationvelocitybetweencodes leads to a biggerdifference in the final hot-spot temperature. • ROXIE normallysimulatesthequenchpropagationslowerthan test results (accordingtoexperts). • Sensitivityanalysisfortheheat transfer coeficientscalingfactors in ROXIE. Case of study: MCBXFB-OD; Self-protection; I=1640 A

  9. Conclusions • Three quench protection strategies have been analyzed for the MCBXF HiLumicorrectors: Self-Protection, Dump Resistor and QHs. • Electro-thermal numerical models for quench simulation have been developed in SQUID and ROXIE. • There are significant differences in the hot-spot temperature between codes when simulating free quench propagation only. Underestimation of the transversal quench propagation in ROXIE seems to be the main reason to the higher temperatures. • MCBXFB-OD has slightly higher self-inductance and stored energy than the MCBXFA-ID. However, as the longitudinal quench propagation velocity is the same, the adjacent turns are quenched faster in the shorter magnet, spreading faster the initial normal zone, and, therefore reducing the final temperature compared to the MCBXFA-ID (240 K Vs. 270 K at ultimate, according to SQUID). • Self-protection strategy is chosen for MCBXFB (ID and OD). • MCBXFA Outer Dipole should be protected with a Dump resistor. • Test measurements will show if a Dump resistor is necessary for the MCBXFA Inner Dipole. Alejandro Fernandez Navarro– 13th February 2019

  10. Thank you for your attention

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