Comparison of Microwave and Mechanical Measurements of FXA-001 Structure.

1. Comparison of Microwave and Mechanical Measurements of FXA-001 Structure. • FXA-001 Structure • Single cell measurements • Mechanical measurements • Setup for bead-pull measurements • Plunger and bead-pull measurements • Tuning of FXA-001 • Summary Tug Arkan, Harry Carter, Dave Finley, Ivan Gonin, Temir Khabibouline, Gregg Kobliska, Gennady Romanov, Nikolay Solyak, Ding Sun, Evgeni Borissov. Nikolay Solyak Structures Workshop@SLAC

2. FXA-001 Structure. It is the first X-band (11.424 GHz) RF structure built, measured and tuned at FNAL. It is tapered structure about 20 cm long, made of 20+3 cells. It is named FXA-001. Note the cells, couplers, rf flanges, water pipes, beam tubes. It took a little more than nine months. We have our first X-Band structure. Nikolay Solyak Structures Workshop@SLAC

3. FXA-001 is made according to SLAC’s design of T20VG5 for NLC High Gradient Testing. • 45 mm RF disks were fabricated by two different vendors LaVezzi Inc. (3 sets) and Medco Inc. (2 sets). • An outside vendor fabricated the Input and Output RF Couplers. Contour Manufacturing and Metrology Inc. (CMM) is a diamond turning ultra precision machine shop and it is located at Troy, MI. Cell and coupler production. Nikolay Solyak Structures Workshop@SLAC

4. FXA-001 Disk Specifications D=8.74268mm Cell dimensions: 2a, 2b, t (iris thickness), D (cell length) and R=t/2 (round ris). Nominal Frequency = 11.417 GHz Nikolay Solyak Structures Workshop@SLAC

5. RF measurements for LaVezzi and MedCo disks LaVezzi disks MedCo disks Nikolay Solyak Structures Workshop@SLAC

6. For MedCodiscs the random scattering of frequencies were found to be rather small, but some systematic error for “0”-like mode of approximately 20 MHz exists in both sets. To evaluate which dimension is responsible for this systematic error a linear approximation of the set-up frequencies has been used. Assuming that the errors a, b are small, the frequency shifts for both modes can be expressed as 2a, 2b deviations for LaVezzi and MedCo disks Frequency derivations are well known from cal- culation. So,errors a and b can be found. LaVezzi discs have smaller systematic errors and bigger random errors. But working frequency higher than 11.424 GHz Nikolay Solyak Structures Workshop@SLAC

7. Errors in bead pull measurements Wave, reflecting from cell vs. cell number at 11.400 GHz Error in frequency measurement for FXA-001 is about  0.6 MHz Nikolay Solyak Structures Workshop@SLAC

8. Mechanical measurements Cordax Coordinate Measuring Machine in QC Laboratory OGP Optical CMM Nikolay Solyak Structures Workshop@SLAC

9. Iris Profile Measurements Vendor #1 (LaVezzi) looks “good” here. … but would not pass single disk RF QC due to large disk to disk variations. Vendor #2 (MedCo) looks “not good” here. … but single disk RF QC showed very good disk to disk control. Nikolay Solyak Structures Workshop@SLAC

10. Frequency Calculation with MedCo real Iris Profile Freq. nominal = 11.417 GHz actual = 11.394 GHz Nikolay Solyak Structures Workshop@SLAC

11. Frequency Calculation with MedCo iris Profile Nikolay Solyak Structures Workshop@SLAC

12. RF measurements on FXA-001 Network analyzer. Bead pull support. Pulley. Data acquisition and data analysis is controlled by computer. Bead pull setup in RF Factory Clean Room A Nikolay Solyak Structures Workshop@SLAC

13. RF Measurements on FXA-001(G.Romanov, D.Sun, I.Gonin, T.Khabiboulline) Bead Pull Principle • A network analyzer puts an rf wave into the structure composed of cells and couplers. Some of the wave is transmitted, some is reflected, and the reflected power measured and analyzed. • A metal “bead” (shown as “needle” in the figure) is pulled along the length of the structure and disturbs the rf wave. • The analysis yields the amplitude and phase of the wave. From PAC95 paper on DESY S-Band setup Nikolay Solyak Structures Workshop@SLAC

14. RF measurements on FXA-001 (1) RF Measurements on FXA-001 Im vs. Re part of reflected rf wave at 11.400 GHz before tuning. Note: You want 11.424 GHz; thus the cells are about 24 MHz low. • The bead is pulled through the structure at a constant speed over about 140 seconds. • Data is taken at constant time intervals. • The data taking window is about 10 msec. Nikolay Solyak Structures Workshop@SLAC

15. RF Measurements on FXA-001 RF measurements on FXA-001 (2) Amplitude of reflected rf wave at 11.400 GHz before tuning as a function of time. • You want this to be flat - which it isn’t. • This is the same measurement as the previous slide but it is easier to see that every third peak is smaller than the other two. Nikolay Solyak Structures Workshop@SLAC

16. Tuning of FXA-001 structure Tuning of FXA-001 Nikolay Solyak Structures Workshop@SLAC

17. RF measurements on FXA-001 Amplitude vs. time after coupler tuning at 11.422 GHz. Nikolay Solyak Structures Workshop@SLAC

18. Summary • First Accelerating Structure FXA-001 was built, measured and tuned at FNAL • Built RF setups for low-power RF measurements. (RF Factory). • Mechanical and RF QC of discs discovered noticeable errors in disk dimensions, made by vendors. This errors will be fixed in next structures. • Automation of RF measurements. Data acquisition and data analyzing is controlled by computer. • FXA-001 structure was measured and tuned to working frequency 11.424 GHz. Nikolay Solyak Structures Workshop@SLAC