RF Phase Shifter R D Proton Driver Review March

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 Fermilab I. Terechkine 1

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 Fermilab I. Terechkine 2

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. Fermilab I. Terechkine 3

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

Examples of Phase Shifters Coaxial Device, 1968 L band (1. 2 – 1. 4 GHz) 350 k. W peak power Field Range 800 – 1500 Oe Phase shift - 600° Insertion loss - 0. 2 d. B Strip-line-based design, AFT for CERN, ~ 2004 352 MHz 250 k. W peak power 25% duty cycle 130º phase shift Fermilab I. Terechkine 5

Examples of Phase Shifters Waveguide-based device, Yoon Kang (ANL) for SNS ~ 2000 805 MHz 500 k. W peak power 8% duty cycle 0. 15 d. B insertion loss Fermilab I. Terechkine 6

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

Performance Requirements Frequency: 1300 MHz ± 1 MHz Phase Change: ± 45° RF Power Ratings: 550 k. W Peak, 1. 5 ms, 10 Hz 550 k. W Peak, 4. 5 ms, 3. 3 Hz Insertion Loss: less than 0. 2 d. B Response time: time constant ~ 30 s Flange: Fermilab WR-650 I. Terechkine 8

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 Fermilab I. Terechkine 9

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

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

High Power Test A 0 1300 MHz Klystron T = 250 µsec F = 5 Hz Existing A 0 interface was used for testing Fermilab I. Terechkine 12

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 SF 6 added Max Power - 2000 k. W (req. 600 k. W) Phase shift - ~ 80° (req. 90° ) Fermilab I. Terechkine 13

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

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

Advanced Ferrite Technology Gmb. H (AFT) Products: 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. Fermilab High Power Circulators Fast Ferrite Tuner Fast High Power Phase Shifter Hybrid Tuner Systems Ferrite Material Electrical Power Supplies for high power inductive loads Power supply will be provided by FNAL I. Terechkine 16

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 Fermilab I. Terechkine 17

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; DONE • Shape YIG block as modeling requires; • Make low level RF measurements; • Make high power measurements; • Investigate ways to improve performance Ongoing R&D • Make a combination “permanent magnet – high frequency winding” bias magnetic system with ferrite core Engineering • 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 Fermilab I. Terechkine 18