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

30th of April 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

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

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

State of the Art – Parallel Biasing 30th of April

State of the Art – Perpendicular Biasing 30th of April

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

State of the Art – Overview NameTuning RangeBiasing Method Type of ferriteQ SIS – 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

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

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

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

Reflection Measurement B /mT Reflection Measurement µ’(f res ) Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q 30th of April

Resonant Measurement B /mT Reflection Measurement µ’(f res ) Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q th of April

Numerical Simulation Results Ferrite ring Teflon foil Inner conductor Outer conductor B /mT Reflection Measurement µ’(f res ) Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% CalculateQ Q th of April

Numerical Simulation Results 30th of April

Numerical Simulation Results 30th of April

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

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 NameTuning RangeBiasingType of ferriteQ SIS – 5 MHzParallelNiZn15 – 94 TRIUMF Booster 46.1 – 60.8 MHzPerpendicularYttrium Garnet2200 – 3600 New Cavity18 – 40 MHzParallel, Perpendicular or both? Yttrium GarnetFrom simulation 37 – 4683

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

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

Resonant Measurement B /mT Reflection Measurement µ’(f res ) Resonant Measurement f res /MHz Q total EigenmodeSimulation f res /MHz d fres /% ExaminedQ ferr Q

Resonant Measurement B /mT35300 Resonant Measurement f res /MHz Q total Refurbished cavityOld cavity B/mT f res /MHz Q total

1-Port Reflection Measurement Notes by C. Vollinger

Preliminary Design