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STEAM Applications Part I The circuit point of view

4th STEAM Collaboration Meeting, Darmstadt, 21-22 Sept. 2017. STEAM Applications Part I The circuit point of view. M. Prioli and the CERN side of STEAM S. Ambjørndalen, B. Auchmann, L. Bortot, A. Fernandez, J. B. Ghini, M. Maciejewski, M. Mentink, A. Verweij. The circuit point of view.

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STEAM Applications Part I The circuit point of view

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  1. 4th STEAM Collaboration Meeting, Darmstadt, 21-22 Sept. 2017 STEAM Applications Part IThe circuit point of view M. Prioli and the CERN side of STEAM S. Ambjørndalen, B. Auchmann, L. Bortot, A. Fernandez, J. B. Ghini, M. Maciejewski, M. Mentink, A. Verweij

  2. The circuit point of view * Quench Protection System QPS* Trim PC Cont. CLIQ* SC Busbar Lfilt M1 M77 Cfilt PC REE1 Rfilt M154 M78 * Coupling Loss Induced Quench protection system REE2 • The behaviour of these additional components cannot be fully captured in the circuit model (nonlinearities, no equivalent lumped element model) • Dedicated models Simulation conventions: SPICE solvers, netlist format, modular libraries Extended modelling capabilities to fit actual needs

  3. Magnet impedance Lfilt M1 M77 Cfilt PC REE1 Rfilt M154 M78 Mn REE2 Field-circuit coupling • Still “part” of this behaviour needs to be modelled in the circuit • Magnet impedance at the operating point • Why? • Mn: Model preconditioning → convergence, limit the number of iterationsEvidence: simple inductor is enough • M1-M154: Accuracy in the circuit resultsEvidence: a simple inductor is not enough

  4. Magnet impedance • How ? • Circuit measurements: MB • Magnet measurements: MB, 11 T, MQXF, magnet prototypes • FE models: future magnets

  5. A. Circuit measurements X 154 Ap1 Ap2 -- measurement – simulation 10 kA 2 kA Lossy inductance model

  6. A. Circuit measurements S. Ambjørndalen Master Thesis (link) • Influence of the rest of the chain of magnets • Fit accuracy decreases at higher frequencies • Is the obtained model accuracy enough for the STEAM applications?

  7. Application 1: short to ground Quenched before the short A: short appearing B: fuse blows Continuous lines: measurement Dashed lines: simulations Family PN Family NP NP PN B A B A

  8. Application 1: short to ground • Simulations • Seen as quenched • “Almost” seen as quenched Measurements

  9. Application 2: double short to ground Quenched before the shorts Short 2 Short 1 Edebris 1,2 = 3 kJ Eshort 1,2 = 22 MJ E EE2 = 80 MJ E EE1 = 800 MJ 9

  10. Application 3: dipole circuit improvements C R 10Ω + 10mF Damp the oscillations on the magnet voltage to reduce spurious triggers of the protection system

  11. Application 4: inter-turn short Assumptions: Location of the short in the inner layer, pole block. Inter-turn short only present at high current, disappearing at low current (300-600 A). Good agreement: the observed QPS signals are compatible with the theory of an inter-turn short. Courtesy of M. Maciejewski

  12. B. Magnet measurements From “Opportunities in High Magnetic Field Science”, 2005 • Some applications indicate the need for more refined circuit models • Measurement conditions: • Current: 0 A ± 1 A rms • Temperature: 300 K - 1.9 K

  13. B. Magnet measurements 1 A 1 kA S. Ambjørndalen Master Thesis (link) The persistent magnetization effect

  14. C. FE models From COMSOL : “ ” Magnetic fields frequency domain form Electrostatic S. Ambjørndalen Master Thesis (link) In Which Regime Is Frequency Domain Wave Electromagnetics Modelling Appropriate? Whenever we want to solve a modelling probleminvolving Maxwell’s equations under the assumption that: All material properties are constant with respect to field strength The fields will change sinusoidally in time at a known frequency or range of frequencies

  15. Application 5: future accelerator circuits Long chains Of high-energy magnets

  16. Application 5: future accelerator circuits Proposal for FCC Powering Sectors (PS) PCs 1 PS 1 PS 2 Proposed circuit layout to reduce the stored energy and limit the voltage to ground during the fast power abort: 4 circuits per PS 54 magnets per circuit Half-arc 8 km PCs 2

  17. Application 6: future accelerator magnets L4,8 L7,3 L1,5 L6,2 L10,14 L13,9 L11,15 L16,12 L4,8 L7,3 L1,5 L6,2 L10,14 L13,9 L11,15 L16,12 Hot-spot 300 K, Vgnd 800 V Hot-spot 280 K, Vgnd 600 V

  18. Future application 5 + 6 Circuit model Lfilt CCLIQ M1 M2 M27 Cfilt Mn PC REE M Rfilt L2 L1 R2 R1 ΔU2 ΔU1 M53 M28 M54 QPS φ, R 2D Electro-thermalField model I

  19. Conclusion FE models Magnet measurement Circuit measurements Present circuit models were successfully employed for various applications For future applications, we are still looking for the quadrature of the triangle

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