Cavity Measurements By Aaron Cheng 4 May 2007

2 Overview RF measurements Waveguide-coax transition

3 RF measurements FETS 4-vane RFQ copper cold model in Imperial College

4 RF measurements Input couplers used

5 RF measurements Some coupling stability problems

6 RF measurements Some coupling stability problems

7 Waveguide-coax transition Studying doorknob wg-coax Coupler with coaxial RF window S11 = dB S21 = dB DescriptionValue [mm] radius of coax conductor33.5 Radius of coax insulator77 coax line length300 doorknob distance from wg end plate doorknob height doorknob radius thickness of doorknob wall10.6 waveguide length1000 window position from waveguide10 window thickness6

8 Studying doorknob wg-coax Coupler with planar RF window S11 = dB S21 = dB DescriptionValue [mm] radius of coax conductor33.5 Radius of coax insulator77 coax line length300 Doorknob distance from wg end plate doorknob height doorknob radius200 thickness of doorknob wall10.6 waveguide length1000 window position from doorknob96.25 window thickness3.5 Waveguide-coax transition

9 Studying doorknob wg-coax Coupler with planar RF window S11 = dB S21 = dB ParameterValue [mm] radius of coax conductor33.5 Radius of coax insulator77 coax line length300 coax distance from waveguide end plate doorknob height doorknob radius thickness of doorknob wall10.6 waveguide length1000 window inner radius229 window thickness6 Waveguide-coax transition

10 Studying t-bar wg-coax Coupler with coaxial RF window S11 = dB S21 = dB DescriptionValue [mm] coax line conductor radius33.5 coax line insulator radius77 coax line length-200 t-shape distance from waveguide end- plate t-shape height153 window height11 position of window from waveguide128.5 Waveguide-coax transition

11 Studying t-bar wg-coax Coupler with planar RF window S11 = dB S21 = dB DescriptionValue [mm] coax line conductor radius33.5 coax line insulator radius77 coax line length-200 distance from waveguide end-plate120.5 t-shape height window thickness8.7 position of window from t-bar center45 Waveguide-coax transition

12 Thermal analysis Vacuum pumping ports and requirements Electron probes and threshold Connecting flanges Waveguide-coax transition

13 Summary 1.Bead pull measurement to be conducted more with unbrazed and brazed RFQ 2.Waveguide-Coax transition will stop at current status until after PAC conference 3.Other matters: Microwave signal generator and amplifier have arrived, currently placed in RAL