1. Mathias Gerbaux CTF3 Collaboration Technical meeting 27/01/2009 30 GHz results from 2008

2. Structures tested in 2008 Only two… HDS4_thick : re-test, bad results. Didn’t reach an accelerating gradient much higher than 60 MV.m -1. C30 speed bump : same geometry as the older 3.5 mm structure except for a « speed bump » lowering the group velocity at the input. Two measurements : fed by the input and by output. 2 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

3. 3 Speed bump (TM 03 ) R=14.398 mm R_iris= 2.428 mm Iris_thickness= 1mm Test structure in disks: 30 cell and identical mode launcher of the “conventional” 2π/3 Ø 3.5 mm Courtesy of Riccardo Zennaro

4. HDS4_thick re-test: whole history In total : 1,244,800 pulses, mainly at 1 Hz corresponding to 5.76 SLAC hours at 60 Hz but crappy data 4 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

5. HDS4_thick re-test : typical running 5 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

6. C30-sb In total : 4,101,250 pulses, mainly at 1 Hz corresponding to 18.99 SLAC hours at 60 Hz 2186 breakdowns Weird things due to calibration problems (now solved) 6 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

7. C30-sb-reversed In total : 1,704,650 pulses, mainly at 1 Hz corresponding to 7.89 SLAC hours at 60 Hz 501 breakdowns Weird things due to calibration problems (now solved) 7 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

8. We figured out at the end of Fall 2008 that calibration was affected by various factors (drifting baselines, temperature…). 8 If we assume the measurement of the incident power is not too wrong… Or at least it is only the absolute calibration that is wrong and it don’t change too quickly. Then, we can calculate the breakdown rate as a function of the accelerating gradient. Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

9. OK Breakdown rate calculation 9 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

10. Breakdown rate vs gradient – speed bump structure -- Old 3.5mm structure 3.5 mm structures comparison No effect of the speed bump on the breakdown rate Need post-mortem examination to see if it has one on the surface damage Vertical error bars calculated assuming an error of 1 on the breakdown number and 500 on the number of pulses. Horizontal error bars : standard deviation of the measured gradient. Red circles are upper limits (no breakdown recorded). Fit doesn’t take into account these points. Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

11. DIY electron spectrometer Rough calculations : with B=0.15 mT (0.1 A), E(e - ) > 200 eV with B=0.75 mT (0.5 A), E(e - ) > 10 keV with B=3.0 mT (2.0 A), E(e - ) > 200 keV with B=7.5 mT (5.0 A), E(e - ) > 500 keV α α B R L l X d CCD 45° Speed bump structure magnet Alumina screen 0 A 1 A Some spots… 3 A Most of the time : 11 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009 filter

12. DIY electron spectrometer – just a few pictures Positive magnetic field Negative magnetic field There is an effect compatible with an electron signal (up to 500 keV) We haven’t a real « zero » position Huge spread of the spot, non-reproducibility No calibration number of electrons – light intensity 12 Needs a collimator ! increasing Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

13. 13 2 structures tested last year :  HDS4_thick showed poor performances  C30-speed bump gave better results  But remember the cumulative duration of the tests is still short compared to SLAC tests (less than 33 h in total for 2008). Conclusion and future plans C30-sb manufactured following the same procedure as the T18 X-band structure currently tested at SLAC with bad results. Spectrometer measurement performed with what was at hand, definitely lacks a collimator ! Poor reproducibility, we are working to see if it can be related to the position of the breakdown (structure acting as a collimator). Nevertheless gave indications of an e - “ beam ” emmitted during the breakdown with an energy up to at least 500 keV. ONE last 30 GHz structure to be tested in 2009 (TM02), optical spectrometry measurement will be done (J. Kovermann). Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

14. 14 Many thanks : Alexandra Andersson Jan Kovermann Steffen Döbert Riccardo Zennaro and for your attention ! to Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

15. 15 C30-sb In blue : my analysis In green : Steffen’s one Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

16. C30-sb-reversed 1 2 3 4 5 6 7 16 Slight improvement with time Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

17. Slope difference : 0.2 % Different points ↔ different analysis (file by file for Steffen’s analysis, single file combining the whole history for mine). C30-sb-reversed 17 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

18. HDS4_thick re-test : ``results´´ Upper limit 18 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

19. HDS4_thick beginning of the test 19 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

20. 20 Energie (keV) Vitesse (m/s) R( 0.15 mT) (m) R(0.75 mT) (m) R(1.5 mT) (m) R(4.5 mT) (m) R(7.5 mT) (m) R(9 mT) (m) R(15 mT) (m) X( 0.15 mT) (m) X(0.75 mT) (m) X(1.5 mT) (m) X(4.5 mT) (m) X(7.5 mT) (m) X(9 mT) (m) X(15 mT) (m) 0.1 A0.5 A1.0 A3.0 A5.0 A6.0 A10.0 A0.1 A0.5 A1.0 A3.0 A5.0 A6.0 A10.0 A 100002.99E+081.86E+023.72E+011.86E+016.20E+003.72E+003.10E+001.86E+00 7.52E-053.76E-047.50E-042.23E-033.70E-034.43E-037.28E-03 50002.99E+081.13E+022.27E+011.13E+013.78E+002.27E+001.89E+001.13E+00 1.23E-046.16E-041.23E-033.64E-036.01E-037.17E-031.17E-02 30002.97E+087.49E+011.50E+017.49E+002.50E+001.50E+001.25E+007.49E-01 1.87E-049.30E-041.85E-035.47E-038.97E-031.07E-021.74E-02 20002.94E+085.38E+011.08E+015.38E+001.79E+001.08E+008.96E-015.38E-01 2.60E-041.29E-032.57E-037.55E-031.23E-021.47E-022.38E-02 10002.82E+083.14E+016.29E+003.14E+001.05E+006.29E-015.24E-013.14E-01 4.44E-042.20E-034.36E-031.26E-022.05E-022.44E-023.98E-02 5002.59E+081.94E+013.87E+001.94E+006.46E-013.87E-013.23E-011.94E-01 7.20E-043.55E-037.00E-032.00E-023.24E-023.88E-026.96E-02 2002.08E+081.10E+012.20E+001.10E+003.66E-012.20E-011.83E-011.10E-01 1.27E-036.19E-031.21E-023.43E-025.88E-027.60E-02#NUM! 100.001.60E+087.17E+001.43E+007.17E-012.39E-011.43E-011.20E-017.17E-02 1.93E-039.36E-031.81E-025.32E-021.51E-01#NUM! 10.005.80E+072.24E+004.48E-012.24E-017.47E-024.48E-023.74E-022.24E-02 6.07E-032.82E-025.73E-02#NUM! 1.001.80E+076.84E-011.37E-016.84E-022.28E-021.37E-021.14E-026.84E-03 1.90E-022.30E-01#NUM! 0.105.90E+062.24E-014.48E-022.24E-027.46E-034.48E-033.73E-032.24E-03 5.75E-02#NUM! Spectrometer calculations α α B R L l X d 45° Speed bump structure magnet Alumina screen

21. DIY electron spectrometer – ``statistical´´ analysis Increasing B field See Jan’s presentation on February, 18 th 21 Mathias Gerbaux - CTF3 Collaboration Technical meeting - 27/01/2009

22. 22 Same phase advance Same P/c Same aperture and iris shape Same field configuration in the iris region but Different group velocity: 4.7% & 2% Different R/Q: 29 kΩ/m & 12 kΩ/m TM 02 structure Is it possible to change some global parameter without changing local field distribution? Only by changing the propagating mode TM 02 regular cell TM 01 regular cell “reference” Test structure in disks: 30 cell and identical mode launcher of the “conventional” 2π/3 Ø 3.5 mm Courtesy of Riccardo

23. 23 TM01: 2π/3 Vg=4.7% TM02: 2π/3 Vg=2.0% a Vg d Direct comparison of Vg Courtesy of Riccardo

24. 24 Why speed bump? From Igor’s presentation at the X band workshop: Very often we do observe, that after accelerating structure processing the most of the surface modifications take place in a few first cells. Also the number of cells involved is correlated with the group velocity, the less the Vg the fewer cells modified. What do we certainly know, the breakdown ignition is a very fast process: 0.1 -10 ns. If so, one can propose the main difference between the “first” and “second” cell is accessible bandwidth. And the lower group velocity the more the difference. The first cell, if breakdown occurs is loaded by the input coupler/waveguide and is very specific in terms of bandwidth. Other words, the first cell can accept “more” energy during breakdown initiation then consequent ones. Worse to mention that we do not know the exact transient behavior of the breakdown and the structure bandwidth could play important role. We can tray by reducing vg in the matching cell HDS 60 L P INC HDS 60 S P INC Courtesy of Riccardo Je ne sais pas si la vidéo restera longtemps à cette adresse mais pour le moment, vous pouvez écouter l’intégralité du « discours à l’occasion du lancement de la réflexion pour une Stratégie Nationale de Recherche et d’Innovation » de Sarkozy. Attention cependant, ses putains d’accents poujadistes et sa façon de nous prendre pour des cons sont susceptibles de vous mettre de très très mauvaise humeur ! http://www.elysee.fr/accueil/ Bonne journée quand même…