1. RF design of compact X-band waveguide components
Alexej Grudiev, CERN
18/05/2016

2. Motivation CLIC is compact and needs compact solutions
With arrival of Toshiba 6MW klystron X-band RF unit becomes more compact -> need for more compact RF components
Combining these more compact RF units requires more RF component -> need for more compact RF components
Furthermore scaling proposed solutions to C- and S-band is straightforward and results in smaller size and cost components at C- and S-band
18/05/2016, A. Grudiev

3. Compact E-plane hybrids: E-Hybrids
E-hybrid for CLIC SAS (2010)
E-hybrid return (2016)
Hybrid Design goal functions:
Old
|S13|2=0.5;
|S14|2=0.5;
|arg{S14}-arg{S13}|=90degree
New
|Re{S13}Im{S14}+Im{S13}Re{S14}|=
Conversion = 0.5 1 2 1 4 2 3 4 3
E-hybrid CLIC
E-hybrid return
Bandwidth at -30 dB
[MHz]
S11
187
312
S12
311
1-2Conv -
220
Max. Surface Fields
Pin=1W
Pin=100MW
E [MV/m]
0.0034 34
0.0043 43
H [kA/m]
0.0091 91
0.0076 76
S [MW/mm2]
1.1e-8
1.1
1.0e-8 1
18/05/2016, A. Grudiev

4. Compact E-plane circular TE11 rotating mode launcher (E-Rotator)3 2 1
Design goal function:
Conversion = 0.5 =
|Re{S13x}Im{S13y}+Im{S13x}Re{S13y}|
Bandwidth at -30 dB
[MHz]
Max Surface Fields
at Pin=1W
at Pin=100MW
S11 78
E [MV/m]
0.0051 51
S12 65
H [kA/m]
0.018
180
1-2Conversion 50
S [MW/mm^2]
2e-8 2
18/05/2016, A. Grudiev

5. Compact Movable Shorts based on Circular Choke
Circular Waveguide D16mm
WR90
20 degree/mm
Parasitic transmission
coaxial port isolation
18/05/2016, A. Grudiev

6. Compact Phase Shifter for WR90
~20 degree/mm of ShortL
18/05/2016, A. Grudiev

7. Electric field at 1W and S-pars for different position of the movable Short
Reflection bandwidth
Is the same as rotator 1W 1W
ShortL
Reflection < -40 dB
Parasitic transmission
to Movable Short <-65dB
18/05/2016, A. Grudiev

8. Adjustable power splitter
Reflection and transmission to vacuum pumping port
Vac.
pump
18/05/2016, A. Grudiev

9. Variable power splitter
Reflection and transmission to vacuum pumping port
Vac.
pump 4 3 1 2
18/05/2016, A. Grudiev

10. Variable polarization circular TE11 mode launcher
Phase difference between port 1 and port 2:
0 degree -> vertical polarization
180 degree -> horizontal polarization
Vacuum pumping port
RF Loads
E-Hybrid
Variable Phase Shifter
Deflecting Structure
E-Rotator
E-Rotator
18/05/2016, A. Grudiev

11. Compact X-band RF load One half cut away Water cooling Vacuum, CF
WR90, RF
Flange-to-flange length ~250mm
Material Ti6V4Al alloy, cond=600000S/m
additive manufacturing
18/05/2016, A. Grudiev

12. Reflections versus roughness, Ra=0 – 50um
Roughness > 10um is expected
18/05/2016, A. Grudiev

13. EM fields, Pin=2W, 12GHz, Ra=0 Pin Esurf_max Hsurf_max Sc_max 2W
11 kV/m
24 A/m
0.024 MW/m2 m
Pin
Esurf_max
Hsurf_max
Sc_max
50MW
55 MV/m
120 kA/m
0.6 MW/mm2
Sc [W/m2]
18/05/2016, A. Grudiev

14. H-field distribution versus Ra for Pin=2W
Ra=0.5um
Ra=1um
Ra=5um
Ra=50um
18/05/2016, A. Grudiev