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1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK HOM Coupler Development for SPL U. van Rienen - H.-W. Glock Universität Rostock.

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Presentation on theme: "1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK HOM Coupler Development for SPL U. van Rienen - H.-W. Glock Universität Rostock."— Presentation transcript:

1 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK HOM Coupler Development for SPL U. van Rienen - H.-W. Glock Universität Rostock - Institut für Allgemeine Elektrotechnik 4 th SPL Collaboration Meeting jointly with ESS 30.6.-2.7.2010 Lund 1.7.2010

2 2 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock... coaxial couplers without fundamental mode filter 2 HOM coupler for SPL - β=1 cavity needed, better than...

3 3 Given coupler design limitations 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 3 23/02/2010 3 Orientation and longitudinal position fixed (cavity construction efforts, space needed for tuner,...) (Inner) diameter (max.) 36 mm Same design on both sides of the cavity (De)mountable, not welded

4 4 "Classical" LEP hook design as starting point 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 4 coaxial 50-Ohm-port (connector not modeled) adjustable capacitive coupling combined E-/H-field coupling, capacity couples to outer conductor support carries liquid helium

5 5 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 5 original picture taken from (courtesy W. Weingarten): E. Haebel, Couplers for cavities, CERN Accelerator School: Superconductivity in Particle Accelerators, Hamburg, Germany, May 1995, p. 231 ff Free design parameters

6 6 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 6 Free design parameters – electrodynamical CAE ~ 20 adjustable parameters CSTStudio© ver 2009/2010

7 7 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 7 Free design parameters – examples

8 8 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 8 Waveguide-Coax-Transmission used to assess coupling connection to external dump coax waveguide connection to cavity: TE 11 – horizontal TE 11 – vertical TM 01 (esp. f acc !) TE 21 – pol. 1 TE 21 – pol. 2...

9 9 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 9 Waveguide-Coax-Transmission used to assess coupling – e.g. example geometry - dependence on hook rotation coax - TE11: E par. coupler coax - TE11: E ortho. coupler 60° good compromise for both polarizations

10 10 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 10 Fundamental mode rejection – e.g. example geometry - dependence on hook rotation minimum of transmission occurs, but not at 704 MHz – to be tuned ! coax - TM01 (couples to fund. mode)

11 11 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 11 Field distributions give hints for design – e.g. example geometry – E-field geometry @ 704 MHz strong capacitive coupling between "hook" and outer conductor => depends directly on "hook" length

12 12 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 12 Status and plan Description of fully parameterized coupler geometry available Many (~20) degrees of freedom to be taken into consideration Primary design criterion: notch filter to be tuned for fundamental mode frequency Combination with cavity (as done for coaxial couplers), Q-determination with pole fitting algorithm Further optimization according polarization sensitivity (mainly TE11, TM11)...... Current density / loss density...... and further constructive aspects (cooling, manufacturing)

13 13 Some news regarding ESS and University of Rostock: 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 13

14 14 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 14 CERN-SPL*-Study, EUCARD**, DoHRo*** @ Rostock CERN-SPL*: HOM damping design for CERN-SPL-Study EUCARD** – WP 10.5.3: HOM distribution and geometrical dependencies (FLASH-1.3, FLASH-3.9, XFEL(?)) needed for HOM coupler signal based beam analysis DoHRo*** – HOM: -WP 1: HOM damping design for BERLINPRO -WP 2: HOM damping design for ESS – high energy part of p-linac -WP 3: Simplified electronics for HOM coupler signal based beam analysis *CERN-SPL: "Design of HOM-Damping for CERN-SPL; funded by German Federal Ministry of Research+Education, Project: 05H09HR5 **EUCARD: EU FP7 Research Infrastructure Grant No. 227579 ***DoHRo: Dortmund-HZB-Rostock – "Innovative Technologien und Komponenten zukünftiger Teilchenbeschleuniger in Strahlungsquellen, funding approved by German Federal Ministry of Research+Education, Project: 05K10HRC

15 15 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 15 CERN-SPL*-Study, EUCARD**, DoHRo*** @ Rostock Staff (% of FTE): Prof. Dr. Ursula van Rienen ( ~ 5%) Dr. Dirk Hecht (administrative; now ~ 5%) Dipl.-Ing. Thomas Flisgen (80% EUCARD**, 20% teaching) Rostock University Dr. Hans-Walter Glock 50% CERN-SPL* 25% EUCARD** 25% DoHRo*** Dipl.-Ing. Mirjana Ivanovska (50%, on pregnancy leave till Oct`10) Dipl.-Phys. Tomasz Galek (100%, Oct.`09 - Jan.`10, 50% July`10 – Dez`10) N.N.-PhD: (50%) CERN-SPL* N.N.-PhD: (50%) Dr. Carsten Potratz (100%, from July`10)DoHRo*** Funding: *CERN-SPL: "Design of HOM-Damping for CERN-SPL; funded by German Federal Ministry of Research+Education, Project: 05H09HR5 **EUCARD: EU FP7 Research Infrastructure Grant No. 227579 ***DoHRo: Dortmund-HZB-Rostock – "Innovative Technologien und Komponenten zukünftiger Teilchenbeschleuniger in Strahlungsquellen, funding approved by German Federal Ministry of Research+Education, Project: 05K10HRC

16 16 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 16 Thank you for your attention.

17 17 Additional stuff: - solver overview - CSC principle - pole identification - Q-determination for coaxial couplers 1.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen 17

18 18 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Used Methods for S-Parameter-Calculation (updated) Transient Solver Hexahedral Grid Frequency Solver Hexahedral Grid Frequency Solver Tetrahedral Grid Fast Resonant Solver Hexahedral Grid Pro Contra Broadband computation of S- Parameters via FFT. Weak coupling between orthogonal modes in rotational symmetric structures. Many time steps are needed to reach steady state due to large time constants. S-Parameters do not show the notch effect of HOM coupler in a reasonable manner. Appropriate for structures with high quality factors. Weak coupling between orthogonal modes in rotational symmetric structures. Long computational time, because each S-Matrix has to be computed for every frequency sample. Very dense mesh is needed for HOM coupler. Appropriate for structures with high quality factors. Less number of unknowns is needed to describe HOM coupler Fast solver available for tetrahedral grids. Strong artificial coupling between orthogonal modes in rotational symmetric structures (e.g. cavity), due to non symmetric grid. Appropriate both for structures with high quality factors and coupler-like set-ups. Weak coupling between orthogonal modes in rotational symmetric structures. Really fast Significant violation of unitarity of S- matrices below cut-off 18 corrected both with a posteriori transformation and software update

19 19 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Concatenation procedure based on scattering properties: Coupled S-Parameter Computation = CSC Split structure in sections Compute scattering (S-) parameters of all sections individually with appropriate solvers Compute overall S-parameters as function of f with special algorithm*, applicable to any structure topology and mode number Derive loaded Q-values from S-parameter spectra *: e.g.: H.-W. Glock, K. Rothemund, U. van Rienen: "CSC - A System for Coupled S-Parameter Calculations", TESLA-Report 2001-25 or K. Rothemund, H.-W. Glock, U. van Rienen: "Eigenmode Calculation of Complex RF-Structures using S- Parameters", IEEE Transactions on Magnetics, Vol. 36, (2000): 1501-1503 and references therein 19

20 20 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen SPL-β=1-cavity: HOM-Q load from full setup computation of coax-coax-transmission following Nov'09 SPL Meeting proposal: 30 mm diameter coaxial couplers Do they provide sufficient HOM damping without fundamental mode filter? 80 mm diameter shortened beam pipes 20

21 21 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Coax with antenna tip depth = 0: 21 to avoid extreme Q-values scaling in a second step using coupler section's S-parameters in order to reach design fundamental mode Q

22 22 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Entire transmission spectrum 0.65 – 2.80 GHz: - more than 400 resonances with wide Q-range 22

23 23 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Using Pole-fitting algorithm* to determine loaded Q's fundamental mode passband - dots: cstStudio© computation - line: fit result f/GHz S 21 /dB 23 *: Hecht, Rothemund, Glock, van Rienen: "Computation of RF properties of long and complex structures", Proc. EPAC 2002

24 24 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Pole-fitting algorithm: "Old" version "Old" algorithm (see reference) 24 f f S 21 /dB

25 25 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Improved pole-fitting algorithm 25 Improved algorithm - corrects for higher order contributions, but still not working in any case see: IPAC10, WEPEC008: Glock, Galek, Pöplau, van Rienen: HOM Spectrum and Q-factor Estimations of the High-beta CERN-SPL-cavities S 21 /dB f

26 26 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Q-value of lowest modes for 0 mm antenna depth: f/Hz Q fundamental mode: Q = 1.04 10 8 fits well to field matching based estimation (4.3 10 8 for single coupler, slightly different geometry) 26

27 27 04/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen Q-value spectrum for 0 mm antenna depth: f/Hz Q 27 Several HOM modes with Q values as high or above fundamental mode (holds also for reduced coupling) – Couplers without filters are not an acceptable solution!


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