1. Fermilab I. Terechkine1 RF Phase Shifter R&D Proton Driver Review March 15, 2005 T. Barrak, B. Foster, I. Gonin, M. Huening, V. Kashikhin, T. Khabiboulinne, A. Makarov, A. Moretti, P. Prieto, J. Santucci, N. Soliak, D. Sun, J. Volk, D. Wildman, and

2. Fermilab I. Terechkine2 RF Phase Shifter R&D Concept of phase & amplitude regulation Performance requirements Types of phase shifters and known experience High power test configuration and results Conclusion

3. Fermilab I. Terechkine3 PD Linac: RF Power Distribution One klystron feeds many cavities. For each cavity, fast change of amplitude and phase of input RF power is required.

4. Fermilab I. Terechkine4 Amplitude and Phase (IQ) Modulator  = (  1+  2)/2  = (  2-  1)/2 11 22 Yttrium Iron Garnet Ferrite Shifters can be built based on: Coaxial line, Strip-line, Waveguide

5. Fermilab I. Terechkine5 Examples of Phase Shifters L band (1.2 – 1.4 GHz) 350 kW peak power Field Range 800 – 1500 Oe Phase shift - 600° Insertion loss - 0.2 dB Coaxial Device, 1968 Strip-line-based design, AFT for CERN, ~ 2004 352 MHz 250 kW peak power 25% duty cycle 130º phase shift

6. Fermilab I. Terechkine6 Examples of Phase Shifters Waveguide-based device, Yoon Kang (ANL) for SNS ~ 2000 805 MHz 500 kW peak power 8% duty cycle 0.15 dB insertion loss

7. Fermilab I. Terechkine7 Phase Control Simulations Frequency follows that of the cavity Cavity RF phase close to nominal Phase Shifter works hard Detailed simulation (M. Huening, EPAC-2004) shows that 200  sec response time is required.

8. Fermilab I. Terechkine8 Performance Requirements Frequency: 1300 MHz ± 1 MHz Phase Change: ± 45° RF Power Ratings: 550 kW Peak, 1.5 ms, 10 Hz 550 kW Peak, 4.5 ms, 3.3 Hz Insertion Loss: less than 0.2 dB Response time: time constant ~ 30  s Flange: WR-650

9. Fermilab I. Terechkine9 Approaching the Problem 1.Develop and test waveguide-based phase shifter; 2.Test the coaxial phase shifter available at FNAL 3.Work with a vendor to build an I/Q modulator

10. Fermilab I. Terechkine10 Waveguide Phase Shifter Main design issues: High power operation Heat management Tuning range Response time Core Coil

11. Fermilab I. Terechkine11 Phase Shifter Mockup Low Level RF Measurements Results of the low level RF measurements are in a good agreement with modeling (HFSS)

12. Fermilab I. Terechkine12 High Power Test A0 1300 MHz Klystron T = 250 µsec F = 5 Hz Existing A0 interface was used for testing

13. Fermilab I. Terechkine13 High Power Test Two methods of phase measurements: 1.Oscilloscope measurements 2.Using available IQ modulator Available phase zone is limited by sparking that develops near the resonance frequencies Max Power - 2000 kW (req. 600 kW) Phase shift - ~ 80° (req. 90° ) SF 6 added

14. Fermilab I. Terechkine14 Further Developments 1.Refining RF design 2.Fast phase shifter prototyping 3.IQ modulator prototyping Anti-Parallel Bias Field Parallel Bias Field

15. Fermilab I. Terechkine15 Coaxial Phase Shifter Coax design is preferred at 325MHz In-house design tested to 660kW at 1300 MHz Tested at 250 kW at Argonne with APS 352MHz Klystron Fast coil and flux return should respond in ~50us

16. Fermilab I. Terechkine16 Advanced Ferrite Technology GmbH (AFT) Products: High Power Circulators Fast Ferrite Tuner Fast High Power Phase Shifter Hybrid Tuner Systems Ferrite Material Electrical Power Supplies for high power inductive loads The IQ modulator from AFT is expected in May: 1 Magic Tee; 1 straight waveguide section; 2 waveguide - coax transition; 2 FFT´s directly connecting to the transition; 1 control unit for setting phase and amplitude and feedback loop; 1 dual directional coupler for amplitude control; 1 arc detection system. Power supply will be provided by FNAL

17. Fermilab I. Terechkine17 Conclusion 1.The prototype of a waveguide-based, 1.3 GHz phase shifter shows excellent maximal power and acceptable phase shift performance. 2.Coaxial phase shifter meets peak power and phase shift requirements both at 1300 MHz and 325 MHz. 3.Commercial prototype of an I/Q modulator due in spring. 4.Average power testing, reaction time testing, and IQ modulator modeling should be the next steps of the R&D

18. Fermilab I. Terechkine18 Phase Shifter Development Line Make low level calibration measurements using “as received” YIG blocks and a large gap dipole magnet Make steel magnet core and copper waveguide; Shape YIG block as modeling requires; Make low level RF measurements; Make high power measurements; Investigate ways to improve performance Make a combination “permanent magnet – high frequency winding” bias magnetic system with ferrite core Make a waveguide transparent for high frequency magnetic-field Make low level a.c. measurements to measure response time Work on a full-scale device design and test DONE Ongoing R&D Engineering