1.7.2010 © 2010 universitÄt rostock | fakultÄt informatik und elektrotechnik hom coupler...
TRANSCRIPT
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
4th SPL Collaboration Meeting jointly with ESS
30.6.-2.7.2010 Lund
1.7.2010
21.7.2010 © 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
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
"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
51.7.2010 © 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
61.7.2010 © 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
71.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 7
Free design parameters – examples
81.7.2010 © 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:TE11 – horizontalTE11 – verticalTM01 (esp. facc !)TE21 – pol. 1TE21 – pol. 2...
91.7.2010 © 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 compromisefor both polarizations
101.7.2010 © 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)
111.7.2010 © 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
121.7.2010 © 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
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
141.7.2010 © 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
151.7.2010 © 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 Glock50% 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
161.7.2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK U. van Rienen – H.-W. Glock 16
Thank you for your attention.
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
1804/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen
Used Methods for S-Parameter-Calculation (updated)
Transient SolverHexahedral Grid
Frequency SolverHexahedral Grid
Frequency SolverTetrahedral Grid
Fast Resonant SolverHexahedral Grid
Pro
Con
tra
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 updatecorrected both with a posteriori transformation and software update
1904/08/2010 © 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
2004/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen
SPL-β=1-cavity:HOM-Qload from full setup computation of coax-coax-transmission
following Nov'09 SPL Meeting proposal: 30 mm diameter coaxial couplersDo they provide sufficient HOM damping without fundamental mode filter?
80 mm diameter shortened beam pipes
20
2104/08/2010 © 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
2204/08/2010 © 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
2304/08/2010 © 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/GHzS21/dB
23
*: Hecht, Rothemund, Glock, van Rienen: "Computation of RF properties of long and complex structures", Proc. EPAC 2002
S21( f )ak
2 i f pkk Qk
Im pk 2Re pk
2404/08/2010 © 2010 UNIVERSITÄT ROSTOCK | FAKULTÄT INFORMATIK UND ELEKTROTECHNIK H.-W. Glock - Thomas Flisgen
Pole-fitting algorithm: "Old" version
"Old" algorithm (see reference)
24
f
f
S21/dB
2504/08/2010 © 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 casesee: IPAC10, WEPEC008: Glock, Galek, Pöplau, van Rienen: HOM Spectrum and Q-factor Estimations of the High-beta CERN-SPL-cavities
S21/dBf
2604/08/2010 © 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 = 1.04 108
fits well to field matching based estimation(4.3 108 for single coupler, slightly different geometry)
26
2704/08/2010 © 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!