27-28 JUNE 2017
-
ESS POWER COUPLERS FOR THE
ELLIPTICAL CAVITIES
CHRISTIAN ARCAMBAL
OUTLINE
• Details of the manufacturing (prototype)
– Window (TiN coating, electron beam welding)
– Tube (realization of the cooling circuit, flange welding, copper coating)
– Doorknob (high voltage insulation, RF gaskets, mechanical aspects)
• Coupler life cycle at CEA
• Conditioning of the 3 first pairs of couplers
• Overview of the production
27-28 June 2017
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2
TIN PLATING (1/4)
• Requirement: 10nm +/-5nm on the ceramic (vacuum side)
• 2 procedures of TiN coating:
– Coating before brazing (on the whole surface of the ceramic)
– Coating after brazing (areas hidden by the chokes)
• Magnetron sputtering deposition
• TiN coating controlled on vitreous carbon samples (10mm*10mm)
• Thickness and stoichiometric (Rutherford backscattering spectrometry)
S
measurements
Sample on the
border of the
ceramic
Limit of the external choke
Limit of the internal conductor
Limit of the internal choke
27-28 June 2017
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TIN PLATING (2/4)
• Results obtained on samples (for plating before brazing)
– Composition of TiN :
Ti:25.73%, Si :1 to 3%, O: 68.73%,N :5.55%  coating such as TiNxOy
,contamination with silicon, lack of nitrogen.
27-28 June 2017
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TIN PLATING (3/4)
•
Thickness: measured with stylus profilometer (Dektak 6m), between 10.1 and
10.4nm on a white glass put above the sample
White glass
S
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TIN PLATING (4/4)
• Results obtained on samples:
– Composition of TiN for plating after brazing
– Estimation of the thickness by calculation
N°sample
1
1
1
5
5
5
5
6
6
6
6
7
7
7
7
8
8
8
8
8
27-28 June 2017
thickness (nm)
5,310516384
5,113830592
4,720459008
3,44200136
4,42543032
3,245315568
3,146972672
3,44200136
2,95028688
3,540344256
5,113830592
0,786743168
0,885086064
0,786743168
0,49171448
1,770172128
2,163543712
0,49171448
1,770172128
1,770172128
% Ti
0,50
0,55
0,54
0,46
0,45
0,47
0,47
0,49
0,49
0,41
0,42
0,44
0,43
0,42
0,44
0,43
0,42
0,47
0,43
0,43
ESS Couplers
%N
0,50
0,45
0,46
0,54
0,55
0,53
0,53
0,51
0,51
0,59
0,58
0,56
0,57
0,58
0,56
0,57
0,58
0,53
0,57
0,57
6
3
2
8
4
1
7
5
6
ELECTRON BEAM WELDING ON THE ANTENNA (1/2)
• Electropolishing before welding on each part then manual polishing with
scotch brite (#3000 non-woven polishing sheet )
27-28 June 2017
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ELECTRON BEAM WELDING ON THE ANTENNA (2/2)
• From another manufacturer, not so smooth aspect
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DOUBLE-WALL TUBE: COOLING CIRCUIT
• Cooling circuit composed of 3 helical channels
• Cooling circuit manufactured with the shrink-fitting method
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WELDING ON THE TUBE
• Welding on the flange (cavity side)
• Welding on the flange (window side)
27-28 June 2017
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COPPER COATING (DOUBLE-WALL TUBE)-1
• Requirements: Copper coating with 10µm(-3/+2µm) thickness and RRR
[20;40] (threshold between RF and thermal aspects)
• electrolytic deposition
• Tubes from 2 manufacturers
• Validation of the coating on cylinder sample
• 1st manufacturer
– Sample OK (use of resin to protect external face)
27-28 June 2017
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COPPER COATING (DOUBLE-WALL TUBE)-2
• Development of a protection tool
27-28 June 2017
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COPPER COATING (DOUBLE-WALL TUBE)-3
• Few tightness problems on the first tubes (coupler in contact with
Wood’s nickel)+copper deposit with lots of defaults
27-28 June 2017
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COPPER COATING (DOUBLE-WALL TUBE)-4
• When the protection tool works, copper deposit with lots of defaults
crack
oxidation
peel
27-28 June 2017
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COPPER COATING (DOUBLE-WALL TUBE)-5
• Obligation to remove the copper deposit (use of nitric acid)
• New copper plating with another firm
27-28 June 2017
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RESULTS ON COPPER COATING-1
Copper plated samples
Copper thickness (µm)
• Control of copper deposit
Dimension (mm)
27-28 June 2017
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RESULTS ON COPPER COATING-2
• RRR measurement (I-V measurement) on « rectangular » sample
(2mm*1mm*100mm)
Resistance (W)
Temperature (K)
Measurement: RRR  [30;39]
27-28 June 2017
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INSULATION-DOORKNOB TRANSITION-1
• First requirement: use of kapton to provide 10kV insulation
• Difficulty to obtain kapton cylinder with “high” diameter (43mm)
• 2 solutions:
– Use of kapton adhesive
– Change of material, PEEK (dielectric constant =3.3 (+/-10%) close to the
kapton one and rather good insulation). Easy to be machined (cylinder
obtained from solid material)
• Test on samples
Aluminum part with shape similar
similar to the doorknob
•
PEEK cylinder insulator
Part of the
(copper)
inner
conductor
Solution not permanent (evolution of the adhesive,
we can tear the adhesive, how to ensure no air
between layers…)
27-28 June 2017
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INSULATION-DOORKNOB TRANSITION-2
• breakdown voltage≥18kV
27-28 June 2017
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RF GASKET (1/2)
• Bal Seal spring used as RF gasket
• Material: Beryllium copper Alloy 25 with silver plating
• 1st trials: the extremities of the spring are twisted to make hooks and
then we link the hooks to close the gasket  when assembly and
disassembly, risk of opening the gasket
27-28 June 2017
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RF GASKET (2/2)
• 2nd trial (solution foreseen for the series):welding the gasket
27-28 June 2017
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DOORKNOB BOX (1/2)
• Initial requirement: welding for the aluminum box (thin wall)
• Difficulty to obtain full penetration welds. After machining, some holes
occur.
27-28 June 2017
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DOORKNOB BOX (2/2)
• 3 kinds of box
– Welded box
– Fully machined box
– Screwed box
27-28 June 2017
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RF CHARACTERIZATION
coaxial-N adapter
IEA 4“1/2 50 Ω
• Doorknob
Coaxial adapter
IEA 4“1/2-coupler coaxial line
Network analyzer
N-waveguide adapter
Doorknob
transition
50cm waveguide
Port 1
• Couplers on the conditioning box
Frequency (Hz)
Network analyzer
Port 2
S11 (dB)
704.42MHz
Port 1
coaxial-N adapter
IEA 4“1/2 50 Ω
coaxial-N adapter
IEA 4“1/2 50 Ω
Coaxial adapter
Coaxial adapter
Windowantenna+ tube
Windowantenna+ tube
at 704.42MHz : S11=-41dB
Conditioning box
27-28 June 2017
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COUPLER LIFE CYCLE AT CEA (1/2)
• Cleaning of each part of the coupler
Tube in
ultrasonic bath
(Tickopur R33)
Coupling box in
ultrasonic bath
(TFD4)
Cleaning of
the antenna
with alcohol
and RBS
T310 if
oxidation
marks
• Assembly in cleanroom
Assembly of the tube
and window on the
coupling box
Vacuum leak test
• Baking (couplers: 170°C for 72 to 120 hours];
pumping system: 120°C for 48 hours then
60°C)
silicon and fibre glass heating tapes for prototype,
furnaces for series
8-9 June 2017
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COUPLER LIFE CYCLE AT CEA (2/2)
•
•
•
•
Conditioning of pairs of couplers (a)
Cleaning before disassembly in cleanroom (b)
Assembly on cavity (c)
Conditioning on the cryomodule (d)
b
a
d
c
8-9 June 2017
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COPPER OF THE WINDOW (1/2)
• During baking, the air side of the window is put under nitrogen to avoid
oxidation of the copper parts
Silicone seal to cover the air part
27-28 June 2017
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COPPER OF THE WINDOW (2/2)
• Evolution of the copper (raw and coating) on the air side
Reception at CEA
3 months after conditioning (ambient temperature)
After conditioning
Pink color
27-28 June 2017
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MEASURED SIGNALS DURING HIGH POWER RF
CONDITIONING
–
–
–
–
–
–
5 Photomultipliers (HAMAMATSU H10721-110):
– Coupler1: 1PM vacuum side (PMV1) , 1PM air side (PMA1)
– Coupler 2: 1PM vacuum side (PMV2) , 1PM air side (PMA2)
– Box: 1PM (PMB)
2 electron pick-up / RF (coupler 1+coupler 2)
• Coupling 80dB (10.4dBm for 1.1MW in TW, 16.4dBm in SW with Emax in front of pick-up antenna)
3 vacuum gauges:IKR070 with TPG300 controller from Pfeiffer (Coupler 1 (VAC1) & 2 (VAC2) + pumping system
(VACB))
5 temperature probes (PT100): 2 for water cooling,1 for each coupler (set up on the window close to the ceramic), 1
for the test box
8 RF signals: Reverse and forward powers for each bidirectional coupler
Security signals: 3 vacuum signals from the controllers, 2 water signals from flow meters (relays)
Flow meter D1
Flow meter D2
VACB
27-28 June 2017
PMA2
PMV2
PuRF2
PUE2
Test box
Bi-directional
Coupler 60dB
50W load
or short
circuit
PtREV
PtDIR
PIDIR
PC_loadDIR
50W load
PIREV
PC_loadREV
PMA1
PMV1
PuRF1
PUE1
PMB
VAC2
Coupler 2
Bi-directional VAC1
coupler 60dB
Coupler 1
Bi-directional
Coupler 60dB
PKREV
PKDIR
klysron
Power supply for the ferrite
Pumping system
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OVERVIEW OF THE CONDITIONING BENCH (1/2)
• Position
Bidirectional coupler
(input Power :incident
& reflected power)
of each diagnosis components
Flow meter (ouptut
water) &
Temperature probes
(water)
Photomultiplier
(vacuum side)
Vacuum gauge
Pumping system
27-28 June 2017
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OVERVIEW OF THE CONDITIONING BENCH (2/2)
Electron pick-up
with bias Tee
Temperature probe
photomultiplier
27-28 June 2017
Box photomultiplier
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RF CHARACTERIZATION ON THE TEST STAND
• Measurement of the reflection coefficient of the pair of couplers with all
the waveguide components (load 50W)
Bidirectional coupler
N-waveguide adapter
Network analyzer
coupler 2
Flexible waveguide 1
Waveguide load
Coupler 2
Coupler 1
Flexible waveguide 1
Conditioning box
Bidirectional coupler
coupler 1
Water waveguide load
Frequency (Hz)
Flexible waveguides
Flexible waveguides
S11 (dB)
704.42MHz
Network analyzer
at 704.42MHz : S11=-24dB
27-28 June 2017
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CONDITIONING
• Conditioning sequence in travelling waves (TW) : RF power ramp from
15kW to 1200kW (pulse width from 50µs to 3.6ms), repetition frequency:
1Hz then 14Hz
• Conditioning sequence in standing waves (SW): 2 positions of short
circuit, RF power ramp from 15kW to 1200kW (pulse width from 50µs to
500µs, 1Hz), from 15kW to 300kW (pulse width: 500µs to 3.6ms, 14Hz)
• Conditioning test stand controlled with Labview then EPICS
• RF time for the 3 first medium beta pairs of couplers: 82 hours, 88 hours
and 106 hours
27-28 June 2017
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FIRST RF POWER RAMP
1st pair of coupleurs
Time (minutes)
Time (minutes)
27-28 June 2017
Pressure (mbar)
Power (kW)
Time (minutes)
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Pressure (mbar)
Power (kW)
Pressure (mbar)
3rd pair of coupleurs (coupling box re-used)
2nd pair of coupleurs
34
CONDITIONING-TRAVELLING WAVE (1/2)
Pressure (mbar)
Pressure (mbar)
Power (kW)
Time (minutes)
PTDIR: Output power (incident)
PIDIR: Input power (incident)
Time (minutes)
Power (kW)
• Results for repetition period=1.2second
PM C2
Time (minutes)
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3ms
2.5ms
2ms
1.5ms
1ms
Time (minutes)
Voltage (V)
100µs
Voltage (V)
200µs
50µs
27-28 June 2017
3.6ms
500µs
•Pulse width (µs)
Pulse width (µs)
PM BOX
35
CONDITIONING-TRAVELLING WAVE (2/2)
Power (kW)
Power (kW)
Pressure (mbar)
Time (minutes)
Time (minutes)
3600µs
1600µs
Pulse width(µs)
800µs
27-28 June 2017
Time (minutes)
2000µs
Voltage (V)
400µs
3000µs
2500µs
Voltage (V)
Pulse width(µs)
1200µs
200µs
Pressure (mbar)
PTDIR: Output power (incident)
PIDIR: Input power (incident)
• Results for repetition period=72 ms
Time (minutes)
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CONDITIONING-STANDING WAVE
800µs
1600µs
2ms
2.5ms
3ms
Pressure (mbar)
3.6ms
Time (minutes)
Time (minutes)
Pressure (mbar)
Power (kW)
Power (kW)
100µs 200µs 300µs400µs
500µs
50µs
72ms (P1)
500µs
300µs
Voltage (V)
50µs
Time (minutes)
Time (minutes)
27-28 June 2017
1.2s (P2) 72ms (P2)
Voltage (V)
Pulse width(µs)
Pulse width(µs)
1.2s (P1)
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TEMPERATURE DURING CONDITIONING
Estimation of the water flow
• Temperature of the water
During the conditioning: for =2.4l/min
T water input=25.6°C

DT
2 l/min
0.97°
2.5 l/min
0.78°
3 l/min
0.65°
T water output=26.2°C
• Temperature of the coupler (TW, 14Hz)
3600µs
2800µs
Time (minutes)
27-28 June 2017
Temperature (°C)
Vacuum (mbar)
Power (kW)
2000µs
1200µs
2400µs
800µs
3200µs
1600µs
Time (minutes)
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OVERVIEW OF THE COUPLER PRODUCTION
• Production of the 120 couplers (window, electron pick-up, double-wall
tube, doorknob transition) performed by PMB.
• First couplers of the pre-series foreseen at the end of 2017
• Production of the coupling box performed by SDMS
• First boxes of the pre-series foreseen at the end of October 2017
• Delivery of a second klystron (1.5MW) : July 2017
• Development of a specific area with the possibility to perform the
conditioning of 2 pairs in parallel
8-9 June 2017
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CONCLUSION
• Overview of the manufacturing for prototypes:
–
–
–
–
6 medium beta double-wall tubes
10 windows
8 doorknob transitions
In progress, manufacturing of 6 high beta double-wall tubes (delivery in June
2017)
• Conditioning of 3 pairs of couplers with success (whose 4 couplers
are now assembled in cavities)
• Production of series couplers and series coupling boxes in progress
8-9 June 2017
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Thank you
•ESS Couplers
| PAGE 41
•27-28 June 2017
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