New Materials and Designs for High Power Fast Phase Shifters

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High Power Tests of Novel Fast Phase/Amplitude
Modulators for HINS (Fast Phase Shifters)Robyn
Madrak, APC
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FNAL HINS

• 60 MeV Linac under construction at Fermilabs
  meson building
• Front end of 8 GeV Linac/Project X
• Fast Phase Shifters allow all cavities (and
  RFQ) to be driven by a single klystron gt large
  cost savings
• (shifters provide independent phase and
  amplitude control for each cavity)

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HINS 325 MHz RF
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How it Works
In a coaxial line filled with some material
(ferrite) (?,?? v c/v??
inner conductor shorted to outer conductor at
end ? reflection
inner conductor
B I(solenoid)
outer conductor
ferrite
We vary ? (by changing B, by changing current in
solenoid) thus v and phase of reflected wave
varies
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Output Range Single Phase Shifter
Gyromagnetic resonance (lossy region)
H I(solenoid) (turns/cm)4p/10
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Fast Response Measurement
solenoid (12 AWG wire)
Ch 1 Solenoid Current (50A/div)
Ch 3 PhaseShift (17º /div)
gyromagnetic resonance
slot
useful phase shift range low loss

• Outer conductor is slotted to eliminate eddy
  currents
• Useful phase shift range above resonance 50?s,
  110
• This gives an average slew rate of 2.2/?s
• (twice as fast as design spec)

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Vector (I/Q) Modulator
Modulates phase and amplitude independently Wit
h ?? (??2 - ??3)/2 ? (??2
??3)/2 Output power cos2(??) Output phase ?
water load
circulator
Four Port Hybrid
Input ?
Output ? to circulator and cavity
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Two Sizes

• Lower Power 1??
• lt 75 kW
• for each of the cavities
• Higher Power 3??
• 550 kW
• for the RFQ only
• (radiofrequency quadrupole)

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High Power Tests at Meson Lab
RF component test cage up to 2.5 MW
325 MHz klystron
Cavity test cave 25 kW line, 250 kW line
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Vector Modulators(for Cavities) High Power Tests
? Vector Modulators work well to gt 75 kW
here, solenoids on both phase shifters driven by
one power supply (??1 ??2)
phase (??1 ??2)/2
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Vector Modulator Test with Cavity 6kW
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Vector Modulator Test with Cavity 6kW

• Phase shifters (solenoids) driven independently
  by 2 supplies
• Output power cos2 (??1 -??2)/2
• Relative levels (range) 13.6 dB

current, solenoid 1
current, solenoid 2
output power cavity gap monitor
current, solenoids 1 and 2

• Phase shifters (solenoids) driven in series by
  1 supply
• phase (??1 ??2)/2
• phase range 155 degrees

phase detector cavity gap monitor relative to
input
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RFQ Vector Modulator

• 3?? Phase Shifters good up to gt 300 kW
• (req. 250 kW each)
• 3?? Hybrids arcing at 350 kW
• ? Will procure larger 6? hybrid

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Conclusions/Summary

• Lower Power 1?? Vector Modulators (for cavities)
• very encouraging results
• power/response speed all better than necessary
• these are all of the vector modulators except
  for 1 (for the RFQ)
• 3?? (for RFQ)
• good results for shifters themselves
• Hybrid arced at high power need a larger one