1. PhD project: Development of a Ferrite-Loaded Accelerating Cavity CERN Supervisor: Dr.-Ing. Christine Völlinger TEMF Supervisor: Prof. Dr.-Ing. Harald Klingbeil From Ferrite Characterization to Preliminary Design of Ferrite Loaded Accelerating Cavity Johannes Eberhardt CERN, Beams Department / TU Darmstadt, TEMF Institute

2. 30th of April 2015 2 Motivation: Ferrite Loaded Accelerating Cavity ▪Idea: Same RF system to accelerate different types of particles → Accelerating Cavity with frequency swing 18 – 40 MHz ▪Cavity design with electromagnetic simulation program → Relative permeability and losses of ferrite as input for simulations Ferrite Cavity

3. Introduction – How does an accelerating cavity work? accelerating gap beam pipe cylindrical structure E RF H RF λ/4 30th of April 2015 3

4. Motivation – Why Ferrite Loaded? ferrite ring 30th of April 2015 4

5. State of the Art – Parallel Biasing 30th of April 2015 5

6. State of the Art – Perpendicular Biasing 30th of April 2015 6

7. State of the Art – 2 Directional Biasing ▪First applying H 1 ⊥ → operating point close to saturating magnetization ▪Rotating direction to H 2ll → modest increase in bias field 30th of April 2015 7

8. State of the Art – Overview NameTuning RangeBiasing Method Type of ferriteQ SIS 180.62 – 5 MHzParallelNiZn15 – 94 TRIUMF Booster 46.1 – 60.8 MHz PerpendicularYttrium Garnet2200 – 3600 New Cavity18 – 40 MHzParallel, Perpendicular or both? Yttrium Garnet? 30th of April 2015 8

9. Introduction – Lessons learned Sample 1 Sample 2 Sample 3 Depends on: RF frequency Magnetic bias history Temperature Location in ferrite Bias field orientation Dispersive characteristics Random – degaussed Room temperature Average over volume Perpendicular to RF magnetic field 30th of April 2015 9

10. B /mT Reflection Measurement µ’(f res ) Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q From Ferrite Characterisation to FLC 1-Port Reflection Measurement Resonant Measurement Simulation of Resonant Measurement 30th of April 2015 10

11. Reflection Measurement I bias B bias B /mT3540300 Reflection Measurement µ’(f res ) Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q 30th of April 2015 11

12. Reflection Measurement B /mT3540300 Reflection Measurement µ’(f res )138.01.17 Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q 30th of April 2015 12

13. Resonant Measurement B /mT3540300 Reflection Measurement µ’(f res )138.01.17 Resonant Measurement f res /MHz18.823.443.7 Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q 9401046 30th of April 2015 13

14. Numerical Simulation Results Ferrite ring Teflon foil Inner conductor Outer conductor B /mT3540300 Reflection Measurement µ’(f res )138.01.17 Resonant Measurement f res /MHz18.823.443.7 Q total 9401046 EigenmodeSimulation f res /MHz18.623.143.3 d fres /%1.11.30.9 CalculateQ Q8355000 30th of April 2015 14

15. Numerical Simulation Results 30th of April 2015 15

16. Numerical Simulation Results 30th of April 2015 16

17. Preliminary Design of FLC 18 – 40MHz Simulation InputSimulation Results for V acc =1kV µ’(f res ) f res /MHz R/Q/ΩP/W 83517.63721363.3 1.17500040.946831081 Ferrite stack Beam pipe Accelerating gap Example V acc /kVP/kW 8.34.4 62.53.9 1125mm 30th of April 2015 17

18. Conclusion and Outlook ▪Measurement of relative permeability and losses of ferrite material ▪Simulation model of resonant measurements setup ▪Preliminary design of ferrite loaded accelerating cavity ▪Influence of non-uniform µ’ has to be analysed ▪RF power measurements have to be done ▪FLC model will be further elaborated 30th of April 2015 18 NameTuning RangeBiasingType of ferriteQ SIS 180.62 – 5 MHzParallelNiZn15 – 94 TRIUMF Booster 46.1 – 60.8 MHzPerpendicularYttrium Garnet2200 – 3600 New Cavity18 – 40 MHzParallel, Perpendicular or both? Yttrium GarnetFrom simulation 37 – 4683

19. Permeability Spectra of G-510 – Static Bias Field Same method but for different bias field H bias is applied perpendicular to magnetic RF field. I bias H bias

20. High frequency Permeability Spectra of G-510 H bias is applied perpendicular to magnetic RF field.

21. Resonant Measurement B /mT3540300 Reflection Measurement µ’(f res )138.01.17 Resonant Measurement f res /MHz18.823.443.7 Q total 9401046 EigenmodeSimulation f res /MHz d fres /% ExaminedQ ferr Q

22. Resonant Measurement B /mT35300 Resonant Measurement f res /MHz18.843.7 Q total 91046 Refurbished cavityOld cavity B/mT3530035300 f res /MHz18.843.776200 Q total 9104635301

23. 1-Port Reflection Measurement Notes by C. Vollinger

24. Preliminary Design