324MHz FETS RFQ RF measurement and components By Aaron Cheng 18 December 2006.
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Transcript of 324MHz FETS RFQ RF measurement and components By Aaron Cheng 18 December 2006.
324MHz FETS RFQ RF measurement and components
By
Aaron Cheng
18 December 2006
2
Overview
1. Bead-pull measurement 2. RF coupler preliminary design approach
3
Bead pull measurements
ISIS copper cold model in Imperial College
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Bead pull measurements
Bead pull results on ISIS copper cold model
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Bead pull measurements
Bead pull results on ISIS copper cold model
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Bead pull measurements
LabVIEW beadpull measurement control program
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•Presentation on ‘High Power RF couplers’ by James Rogers in ASTeC
•Investigate on coax structure to match 50ohm impedance @ 324MHz
•investigate waveguide-to-coax transition
•RF energy transferred from klystron to RFQ via waveguide, waveguide-coax transition, RF window and RF input coupler.
•@ waveguide-coax transition structure, coupling @ lowest mode TE101
•Study klystron output waveguide-coax transition structure (magnetic field coupling); Current waveguide size is WR2300
•Implementing a doorknob structure (electric field coupling)
RF coupler preliminary design approach
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RF coupler preliminary design approach
•Coax matching.
•Outer diameter of insulation fixed @ 40mm (KF flange size on RFQ), modelled as vacuum
•Optimized conductor to obtain 50ohm match inner diameter = 17.4mm
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RF coupler preliminary design approach
•Studying klystron o/p T-struc wg-coax
•Coupler varied in distance from waveguide end-plate and in height
S11 = -3.32dB S21 = -2.589dB
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RF coupler preliminary design approach
•Studying doorknob wg-coax
•Increased wg length
•Coupler varied in distance from waveguide end-plate and in height
S11 = -22.59dB S21 = -0.717dB
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Summary
1. Bead pull measurement almost ready to go. Other issues are finding suitable bead
2. Waveguide-Coax transition design started and on-going. Current status:
• Electric field probing show promising results
• Investigate into half-height wg, different T-shape geometry, conductor with cooling pipes etc.
3. Other tasks:
• Microwave signal generator and amplifier in the process of purchasing:
• Delivers 20W-50W to drive klystron and RF control purposes