Waveguide 1

Additive Manufacturing for Xband applications
Alexej Grudiev
5/02/2014
CLIC14 workshop
Acknowledgements
• BE-RF
• Miriam Colling
• Alexej Grudiev
• EN-MME
• Said Atieh
• Ofelia Capatina
• Floriane Leaux
• Raphael Leuxe
• Thomas Sahner
• Ignacio Santillana
• TE-VSC
• Sergio Calatroni
• Ivo Wevers
Additive manufacturing
Process
1. Model designed in CAD
2. CAD file sent to additive manufacturing system
3. Model divided into slices
4. 3D product sculpted from powdered material layer by layer using
the specified technique
EOS – SLS, http://www.eos.info/additive_manufacturing/for_technology_interested
Number of good reasons to try
Typical materials
Technical data Ti64
Ti64 DC electrical conductivity: 600000 S/m, two times lower than stainless steel
• Relatively low accuracy
• Big roughness (much larger than skin depth)
• Low DC conductivity
Obvious RF application is a
broad-band all-metal dry
RF load
High power/E-field performance of Ti
DC breakdown thresholds
30 GHz high power performance, PAC2007
Three stages of the project
1. Low power prototype for material and fabrication
characterization
1.
2.
3.
4.
DC conductivity and RF losses
UHV compatibility: leak tightness and outgassing
Shape accuracy and Roughness
Mechanical strength and Metallurgy
2. Prototypes for high power tests
1. Integration of cooling
2. High power performance
3. Design of the RF load
4. RF load prototype
Prototype Design
 Prototype modelled in HFSS
 WR90 end tapered to 13mm by 2mm middle
200mm
Waveguide manufacturing methods
Waveguide 1:
EOS – Selective laser sintering
Waveguide 2:
Grenoble INP – Electron beam
melting
5
Waveguides 3, 4 and 5:
Concept – Selective laser
melting
 Length: 20cm
 Material: Titanium alloy
RF measurements using VNA
• Obtained data for S(1,1), S(1,2), S(2,1) and S(2,2) parameters for each
of the five waveguides
• Measurements required careful handling - movement in cables cause
readings to change
• Measurements repeated three times for each waveguide for reliable
results
RF Results
Comparison of S(1,1) parameter
0
-5
-10
-15
S(1,1)/dB
-20
-25
-30
HFSS simulation
-35
Waveguide 1
Waveguide 2
-40
Waveguide 3
Waveguide 4
-45
Waveguide 5
-50
11.4
11.6
11.8
12
Frequency/GHz
12.2
12.4
12.6
RF Results
Comparison of S(1,2) parameter
0
-5
-10
S(1,2)/dB
-15
HFSS simulation
-20
Waveguide 1
Waveguide 2
-25
Waveguide 3
Waveguide 4
Waveguide 5
-30
-35
11.4
11.6
11.8
12
Frequency/GHz
12.2
12.4
12.6
DC conductivity measurements
Titanium alloy conductivity: 6E+5 S/m
Two types of DC measurements:
1. Four probes in contact with middle section
6mm
2. Two probes in contact with middle while clamps on flange
provide voltage difference
62mm
DC Results
Titanium alloy conductivity: 6E+5 S/m
Method 1
Method 2
Waveguide No.
Conductivity/ S/m
Waveguide No.
Conductivity [S/m]
1 - EOS
641025
1 - EOS
716093
2 - INP Grenoble
368595
2 - INP Grenoble
480179
3 - Concept laser
496771
3 - Concept laser
571880
4 - Concept laser
500000
4 - Concept laser
557176
5 - Concept laser
522739
5 - Concept laser
580343
Apply all DC cond. to HFSS
waveguide and obtain values for
all 3 parameters in each case
aqw
Nominal HFSS values:
‘aqw’=14.2mm ‘a’=13mm
Roughness=0µm
a
Determining parameters
Determining 'aqw' of waveguide 1 (cond=641025 S/m)
0
-10
S(1,1)/dB
-20
-30
-40
HFSS Nominal: aqw='14.2mm'
Measured: Waveguide 1
-50
Matched: aqw='13.9mm'
-60
11.4
11.6
11.8
12
Frequency/GHz
12.2
12.4
12.6
Determining parameters
Determining 'a' and roughness of waveguide 1 (cond=641025 S/m)
0
-5
S(1,2)/dB
-10
-15
HFSS Nominal: a='13mm' aqw='14.2mm' rough='0um'
Measured: Waveguide 1
-20
Matched: a='12.91mm' aqw='13.9mm' rough='50um'
-25
11.4
11.6
11.8
12
Frequency/GHz
12.2
12.4
12.6
Table of parameters
HFSS Nominal: a=‘13mm’ aqw=‘14.2mm’ rough=‘0um’
Waveguide No.
DC cond. (S/m)
(method 1)
‘a’ (mm)
‘aqw’ (mm)
HFSS roughness
(µm)
dB % difference at 12
GHz
1-EOS
641025
12.91
13.9
>50
-13.12
2-Grenoble
368595
12.74
14.0
>50
-2.78
3-Concept
496771
12.75
14.0
>50
-33.90
4-Concept
500000
12.79
14.0
>50
-19.71
5-Concept
522739
12.80
14.1
>50
-88.03
Waveguide No.
DC cond. (S/m)
(method 2)
‘a’ (mm)
‘aqw’ (mm)
HFSS roughness
(µm)
dB % difference at 12
GHz
1-EOS
716093
12.90
14.0
>50
-20.29
2-Grenoble
480179
12.74
14.0
>50
-15.56
3-Concept
571880
12.74
14.0
>50
-40.02
4-Concept
557176
12.79
14.0
>50
-25.79
5-Concept
580343
12.80
14.1
>50
-95.53
Tables show:
• Values for each modified parameter: ‘a’ , ‘aqw’ and HFSS roughness
• 100-300 micron differences
• Change in parameters required to provide HFSS results which agree with
those produced by the VNA for each waveguide
Metrology
Microtomography – X-ray non destructive testing
Radioscopic image
acquisition
1
2
Post processing
3
Images: RX solutions gallery http://www.rxsolutions.fr/#!untitled/zoom/cjjm/i47og1
3D reconstruction
Metrology Results
 Blue lines show lack of material
 Red lines show excess material
Metrology Results
 First three waveguides were measured using microtomography to determine dimensions ‘a’ and
‘aqw’
 Measured ‘a’ at 3 points and ‘aqw’ and 2 points and an average was found
 Waveguide 1 and 3 < 100micron difference from nominal
RF+DC
measurements:
Waveguide No.
DC cond. (S/m)
(method 1)
‘a’ (mm)
‘aqw’ (mm)
HFSS roughness
(µm)
dB % difference at 12
GHz
1-EOS
641025
-13.12
368595
>50
-2.78
3-Concept
496771
13.9
14.0
14.0
>50
2-Grenoble
12.91
12.74
12.75
>50
-33.90
Vacuum
 Waveguide 1, 3,4 and 5 are leak tight, OK for UHV
 Waveguide 2 was not be able to pump down due
to presence of small holes
Mechanical testing and
metallographic observations
Waveguide 2
Waveguide 3
After etching
Before etching
Waveguide 1
W1 shows least porosity
W2 shows large porosity
W3 shows different
microstructure
Summary of the results obtained after
tensile tests of the samples
WG #
Company
Emod (GPa)
Rp0.2 (MPa)
A%
UTS (MPa)
1
3T
112 ± 1
1097 ± 8
2±0
1139.8 ± 3.0
2
IPN
51 ± 0
830 ± 36
11 ± 2
904.8 ± 20.4
3
Concept Laser
108 ± 1
825 ± 11
12 ± 3
893.4 ± 10.7
120
910 - 958
12-16
972 - 1030
Table value for standard
material (www.matweb.com)
OK
OK
Summary
• Laser melting fabrication is validated for two
manufacturers
• EBM fabrication requires some improvements
• Next step:

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