SPL power coupler

Eric Montesinos / CERN-BE-RF-SR

Possible proposed designsPart II : designs comparison

SPL power coupler

16/03/2010

2


Summary

Comparison of proposed designs: SPL-CEA coaxial disk

water cooled window SPL-SPS coaxial disk air

cooled window SPL-LHC cylindrical air

cooled window Design issues

Waveguides Titanium coating RF simulations Coupling box

Construction process

Conditioning process

Mass production

New proposed schedule

Conclusion16/03/2010


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Three possible remaining designs

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All use the same double walled tube All use the same vacuum gauge, electron monitor and arc

detector We have designed them to be compatible without modifying

the cryomodule


4

Three possible remaining designs

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SPL-CEA HIPPI coaxial disk water cooled window SPL-SPS coaxial disk air cooled window SPL-LHC cylindrical air cooled window

5


Coaxial disk water cooled window

CEA design based on a coaxial disk ceramic window as in operation at KEKB and SNS, modified for 704MHz

Advantages High power capability, tested up to 1MW with

2ms / 50Hz on warm test cavity and on cold cavity last week

Matched window, this allows to easily change the waveguide position

Commercially produced window (Toshiba)

Drawbacks Window and antenna are water cooled:

Not following CERN vacuum group recommendations

Needs accurate mounting Difficult DC HV biasing due to water:

Need insulating pipes (X-rays, radiation,... More maintenance and operational costs)

Need a second air cooling circuit for the waveguide: Doubles the operational needs: water and air

systems

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Antenna and outer ceramic water cooling

Waveguide air cooling

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Coaxial disk water cooled window

Quite complex brazing process (compare to SPS and LHC)

Water seal to be modified from organic (acceptable for test) to metallic (for long term operation without maintenance)

the tolerances are very tight

No flexibility for the antenna: Stress to the ceramic RF contact depends on tolerances Possible water leak if misalignment

(already happened)

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7


Coaxial disk air cooled window

Design based on a coaxial disk ceramic window similar as the one in operation on the CERN SPS TWC 200MHz power load

Advantages Very simple and well mastered brazing of

ceramic onto a titanium flange High power capability (500kw cw) Very easy to cool with air Waveguide as “plug and play” mounting,

absolutely no stress to the antenna DC HV biasing very simple, with again a

“plug and play” capacitor fitting, and again no stress to the ceramic due to finger contact

Least expensive of the three couplers !

Minor drawback Ceramic is part of the matching system,

fixes the waveguide position

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Antenna and outer ceramic air cooling

Ceramic and waveguide air cooling

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Coaxial disk air cooled window

Very simple brazing process: Titanium outer flange:

Dilatation coefficient near ceramic Surface hard enough for vacuum

copper seals Inner tube in copper 1.2mm

thickness to allow easy brazing

Antenna inner upper part has been designed: With spring washers for a good

RF contact between the upper and lower inner conductor sections

Without any stress to the ceramic Allowing a correct air flow

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Spring washers

RF contact

SPS Window: very simple brazing process

RF contact without stress to the ceramic by compression of the outer line through the

air “cane”

Air “cane”

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“Plug and play” waveguide system

Need additional 50 Ω outer lines: Vacuum side for monitoring

vacuum, electron, light, … Air side for RF matching and for air

cooling of the ceramic

“Plug and play” waveguide and biasing capacitor

There is a finger contact all around the capacitor to avoid stress on the ceramic

This waveguide mounting method has already been used successfully for the LHC couplers

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Cylindrical air cooled window

Design based on the same cylindrical window as the LHC couplers: Long and difficult process to achieve reliability of

the window, the final design was obtained after more than six years of studies

As the design was complex, we keep it exactly as it is

Instead of changing the ceramic design we have adapted the line to the ceramic

Advantages High power capability window, LHC proven (575kW

cw full reflection, could be more…) Simple to cool with air Absolutely free of mechanical stress on the

antenna Same “plug and play” waveguide and DC capacitor

as previous design, no stress to the ceramic Simplest version to assemble !

Drawbacks Ceramic is part of the matching system, fixes the

waveguide position Possible multipacting due to the outer conical

outer line

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Ceramic and waveguide air cooling

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Cylindrical air cooled window

LHC window is a huge improvement over the LEP window, with less losses and higher power capability

We still not know the upper power limit of the LHC window The LHC coupler were powered up to

575kW cw full reflection (SW) for several hours all phases

Klystrons failed, not the coupler !

The LHC window appears to be really robust To date 30 LHC couplers have been built

and tested, 16 are in operation in LHC

A new coupler using exactly the same ceramic window is under construction for ESRF and SOLEIL → Standardization of the ceramic

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ESRF-LHC new design

First EB welding(mechanical)

Second EB welding(mechanical and vacuum)

Third EB welding(mechanical and vacuum)

LHC window:Two solid copper collars brazed to the ceramic

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“Plug and play” waveguide system

Same “Plug and play” waveguide and biasing capacitor as with the coaxial air cooled window

The waveguide has just one contact with the body line

There is a finger contact all around the capacitor to avoid stress on the ceramic

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Comparison: Titanium coating

LHC, coating done twice: First coating on the top and the

bottom edges of the ceramic (electrical continuity)

Brazing of the copper collars Second coating on the inside of the

ceramic → Double the costs

SPS, only one coating: Straight forward Done after brazing

Toshiba process: Probably one coating What about the part of ceramic

masked by the chokes?

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First coating:R = 0.5 MΩ

Second coating:R = 2 MΩ

One coating:R = 2 MΩ

One coating:R = 2 MΩ

What about the part of ceramic behind the choke ?

?

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Comparison: S11 simulations

Cavity bandwidth704 MHz / Qext (1.2 x 106) =

586 HzDesign

Center frequency

[MHz]

Bandwidth< - 25 dB

[MHz]CEA 702.8 25.2LHC 704.2 13.2SPS 704.4 26.2

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SPL-CEA

SPL-SPSSPL-LHC

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Comparison: Field Strength

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SPL-CEA

SPL-LHC SPL-SPS

Max 751 kV/mwith 1MW



Hodgman, Charles D. & Norbert A. Lange. Handbook of Chemistry and Physics 10th Edition. Cleveland, OH: Chemical Rubber Publishing Co, 1925: 547.

"Spark length (cm), .10; Point electrodes, 3720;

Ball electrodes, 1 cm diameter:

Steady potential, 4560; Alternating potential, 44

00"

3.7–4.5 MV/m

Tipler, Paul A. College Physics. Worth, 1987: 467.

"This phenomenon, which is called dielectric breakdown, occurs in air

at an electric field strength of about

Emax = 3 × 106 V/m."

3.0 MV/m

Rigden, John S. Macmillan Encyclopedia of Physics. Simon & Schuster, 1996: 353.

Air; Dielectric Constant, 1; Strength Es (kV/mm),

33.0 MV/m

Riley, Lewis A. Dielectrics. 1999-2000.

"The dielectric strength of air is about 3 × 106 V/m"

3.0 MV/m

http://www.cs.earlham.edu/~rileyle/p19/lectures/nod17.html

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Waveguides options

If needed, LHC design could be done with a “coaxial conical” extension line to change the waveguide position

We simulated the waveguide with steps to check effects on the field distribution, it reduces the field strength

Using a waveguide without doorknob considerably eases the mounting and reduces the cost (as LHC)

Immediately after the coupler waveguide flange, there will be a flexible waveguide to reduce mechanical stresses

Nevertheless, a supporting tool will be necessary for the coupler waveguide, still to be studied

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Doorknob / reduced height: ~ same field strength

Two steps waveguide: slightly reduces the field strength

LHC design with a

possible conical coaxial

extension to change the waveguide

axis


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Comparison

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Item Coaxialwater cooled

Coaxialair cooled

CylindricalAir cooled

A single window coupler

Possible adjustable coupler

Integration in the cryomodule Vertically above or below the cavity

DC biasing

Air cooled

Matched window

“Plug and play waveguide”

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Coupling box

Will be used to: Connect two couplers in the vertical

position for conditioning Storage and transport chamber with

springs to damp shocks

Solid copper: Low RF losses Strong enough to sustain deformation

due to strong pressure effects Extra external mechanical

adjustment for frequency tuning

Could be EB soldered or assembled from two parts: Vacuum seal Easy to clean, we want to re-use it for

250 couplers !

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Springs to avoid any

shock while transporting

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Construction process We plan to follow an upgraded

LHC coupler construction process:

Build all components: Metrologic controls Mechanical and thermal tests

In clean room (class 100): clean all parts in contact with beam

vacuum with pure water or pure alcohol

Particle counting to validate the cleaning

In clean room (class10): assemble a pair of couplers and

mount them on a test cavity Bake out RF conditioning In clean room (class 10):

mounting of coupler with its double walled tube on SPL cavity

Build all components

In clean room: clean all parts in contact with beam vacuum

In clean room: assemble a pair of couplers and mount them onto a coupling box

Bake out

RF conditioning

Double walled tube and coupler mounted onto the cavity

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Vacuum leak detections after each

major operation

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Construction process

To be carefully followed-up: Assembly tooling Handling with special gloves only,

avoid contamination of surfaces by hydrocarbons, finger prints,…

Optimize the process to minimize the number of handlings

Avoid intermediate packing in polymeric sealed bags (contamination)

Specially designed transport containers

Visit tomorrow of the three facilities: Building 252 class 100 clean room Building 252 class 10 clean room Building SM18 class 10 clean room Would like advice on what we could

improve for high gradient cavities

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Install one cavity with its two power couplers and prepare for conditioning

List of interlocks and monitoring: Vacuum gauges Directional couplers

Light detector Electron monitor Thermal measurements Gas analyzer Air flow meter Water flow meter (power load) …

The tests will be done at CEA Saclay

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TTF III power coupler test bench


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The conditioning loop will be the same as the one used since 1998 with the SPS and LHC couplers: A first direct vacuum loop (red) ensures RF is never applied if pressure exceeds 5.0 x 10 -7 mbar A second vacuum loop (blue), cpu controlled, executes the automated process The interlock vacuum threshold of 5.0 x 10-7 mbar will be chosen, guided by our experience, to protect

the couplers, but also to have an as short as possible conditioning time The settings are adjusted to have minimum attenuation under 1.0 x 10-8 mbar and maximum attenuation

over 2.5 x 10-7 mbar (~40 dB dynamic range with the attenuator)

HF + AM + FMGenerator

Computer controlled attenuator

Vacuum controlled attenuator

RF switch Amplifier CavityInput Coupler Output Coupler Terminating load

CPU

Vacuum analog loop

Vacuum distribution

Vacuum Gauges

Vacuum Gauges

Power measurment

Power measurment

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The conditioning process will be similar to the LHC one:

The process always starts, under vacuum control, with very short pulses of 20 µs every 20 ms

Power level is increased using short pulses up to full power passing slowly through all power levels to avoid “de-conditioning”

Same procedure repeated for initially short then longer and longer pulses up to the maximum length

The conditioning process will be considered finished when the vacuum level decreases below a predefined level (1 x 10-8 mbar for example), while ramping the maximum length pulse

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Double walled tube rough estimate: 15’000 CHFCoupling box rough estimate: 25’000 CHF

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Part List coupling boxRep Nb Désignation Matière

Prix matière (CHF)

Prix MO (CHF)

Prix global (CHF)

1 1 COUVERCLE SUPERIEUR CUIVRE OFE 2000 1600 3600

2 1 COUVERCLE INFERIEUR CUIVRE OFE 2000 800 2800

3 1 BRIDE ENTRÉE INOX 316 LN 444 1200 1644

4 1 BRIDE SORTIE INOX 316 LN 444 1200 1644

5 1 TUBE PIQUAGE VIDE CUIVRE OFE 15 400 415

6 1 BRIDE VIDE INOX 316 LN 164 400 564

Equipement de protection pour le transport 14500

Total 5067 5600 25167

Part List tube double SPLRep Nb Désignation Matière

Prix matière (CHF)

Prix MO (CHF)

Prix global (CHF)

1 1 TUBE CONNECTION HELIUM INOX 10 400 410

2 1 FLASQUE VIDE D ISOLATION INOX 2000 2000 4000

3 2 CORPS INOX FORGE 3D 1500 6000 7500

4 1 1/2 COQUILLES INOX 50 2000 2050

5 1 TUBE CONNECTION HELIUM INOX 10 400 410

Total 3570 10800 14370

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SPL-CEA rough estimate:53’000 CHF

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Part List coupleur SPL type CEARep Nb Désignation Matière

Prix matière (CHF)

Prix MO (CHF)

Prix global (CHF)

1 1 BRIDE SUPERIEURE BODY CUIVRE 100 1600 17002 1 ENTRETOISE SUPERIEUR BODY CUIVRE 230 1600 18303 1 COUPELLE SUPERIEUR BODY CUIVRE 180 2000 21804 1 RACCORD ANTENNE CUIVRE 80 800 880

5 1BAGUE SUPERIEUR DE CENTRAGE ANTENNE CUIVRE 40 1000 1040

6 1 TUBE INTERIEUR CERAMIQUE CUIVRE 25 1000 10257 1 CERAMIQUE OXYDE D' ALUMINIUM 300 3000 33008 1 ENTRETOISE CENTRALE INTERNE BODY CUIVRE 1 800 8019 1 TUBE CONNECTION REFROIDISSEMENT INOX 2 400 402

10 1 PATTE CONNECTION REFROIDISSEMENT CUIVRE 300 400 70011 1 CAPOT DE REFROIDISSEMENT BODY CUIVRE 180 2000 218012 1 COUPELLE INFERIEURE BODY CUIVRE 180 2000 218013 1 ENTRETOISE CENTRALE EXTERNE BODY CUIVRE 180 1600 178014 2 TUBE DE BRIDE UHV CUIVRE 5 500 50515 1 BRIDE UHV INOX 10 200 21016 1 DETECTEUR 800 2500 330017 1 BRIDE INFERIEURE BODY INOX CUIVRE 150 1400 155018 1 BRIDE UHV JAUGE INOX 116 400 51619 1 JAUGE A VIDE PENNING IKR 070 900 90020 1 CONNECTION DOORKNOBS ANTICORODAL 20 400 42021 1 DOORKNOBS ANTICORODAL 150 2000 215022 1 BRIDE DOORKNOBS ANTICORODAL 70 1000 107023 1 GUIDE D' ONDE ANTICORODAL 300 2000 230024 1 ENTRETOISE GUIDE D' ONDE ANTICORODAL 10 400 41025 1 BRIDE GUIDE D' ONDE ANTICORODAL 20 800 82026 1 TUBE ALLEE REFROIDISSEMENT INOX 2 200 20227 1 COUVERCLE ANTENNE INOX 2 200 20228 1 JOINT TORIQUE Ø3 EPDM 2 229 1 BRIDE COUVERCLE ANTENNE CUIVRE 6 500 50630 1 TUBE SORTIE REFROIDISSEMENT INOX 2 200 20231 1 ANTENNE SUPERIEURE CUIVRE FORGE 1500 1800 330032 1 VIS SPECIALE ACOUPLEMENT ANTENNES VIS INOX 1 400 40133 1 CONNECTION ANTENNE SUPERIEURE CUIVRE 4 500 50434 1 JOINT TORIQUE Ø3 EPDM 2 235 1 CANNE SUPERIEURE INOX 10 200 21036 1 FIXATION CANNE INFERIEURE INOX 5 400 40537 1 ACOUPLEMENT ANTENNE CUIVRE FORGE 800 1200 200038 1 ANTENNE INFERIEURE CUIVRE FORGE 1700 800 250039 1 BOUCHON ANTENNE CUIVRE FORGE 50 200 25040 1 CANNE INFERIEURE INOX 20 400 42041 1 BOUCHON CANNE INOX 5 800 80542 1 CANAL DE REFROIDISSEMENT INOX 10 200 210

Total 8470 37800 46270

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SPL-SPS rough estimate:27’000 CHF

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Part List coupleur SPL type SPSRep Nb Désignation Matière Prix matière

(CHF)Prix MO (CHF)

Prix global (CHF)

1 1 CAPOT DE PROTECTION TOLE GRILLAGEE 15 400 415

2 2 BAGUE DE PROTECTION KAPTON PEEK NATUREL 1000 400 1400

3 1 CONDENSATEUR EXTERNE ANTICORODAL 135 800 935

4 1 KAPTON KAPTON 10 400 410

5 1 BAGUE DE SERRAGE ANTICORODAL 2 200 202

6 1 CONDENSATEUR INTERNE ANTICORODAL 40 800 840

7 1 CONTACT RF CUIVRE + DORAGE 50 200 250

8 1 SOCLE CONDENSATEUR ANTICORODAL 35 200 235

9 1 GUIDE D' ONDE ANTICORODAL 300 2000 2300

10 1 BONCHON GUIDE D' ONDE ANTICORODAL 35 200 235

11 1 SOCLE BODY ANTICORODAL 35 200 235

12 1 JOINT RF CUIVRE + DORAGE 0

13 1 BODY ANTICORODAL + CUIVRAGE 80 1000 1080

14 1 CAPOT DE VENTILATION INOX 20 500 520

15 1 JOINT PROFILE U EPDM 2 10 12

16 1 JOINT TORIQUE Ø2.5 EPDM 15 10 25

17 1 BRIDE TITANE TITANE 400 16 416

18 1 CERAMIQUE TITANISEE OXYDE D' ALUMINIUM 300 3000 3300

19 1 EXTENTION JAUGE A VIDE (2 BRIDES + TUBE) INOX + CUIVRAGE 1500 400 1900

20 1 JAUGE A VIDE PENNING IKR 070 900 900

21 1 BRIDE JAUGE A VIDE INOX 116 400 516

22 1 BAGUE DE SERRAGE ANTENNE INOX 2 1000 1002

23 1 BAGUE FILETEE INOX 5 1600 1605

24 1 CANNE INOX 20 400 420

25 1 ANTENNE SUPERIEURE CUIVRE 1700 1200 2900

26 1 INSERT TARAUDE INOX + ARGENTAGE 10 800 810

27 1 TUBE CERAMIQUE + INSERT INOX CUIVRE FORGE 200 800 1000

28 1 ANTENNE INFERIEURE CUIVRE FORGE 1700 800 2500

29 1 BOUCHON ANTENNE CUIVRE FORGE 50 200 250

Total 8677 17936 26613

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SPL-LHC rough estimate:30’000 CHF

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Part List coupleur SPL type LHCRep Nb Désignation Matière Prix matière

(CHF)Prix MO (CHF)

Prix global (CHF)

1 1 CAPOT DE PROTECTION TOLE GRILLAGEE 15 400 415

2 2 BAGUE DE PROTECTION KAPTON PEEK NATUREL 1000 400 1400

3 1 CONDENSATEUR EXTERNE ANTICORODAL 135 800 935

4 1 KAPTON KAPTON 10 400 410

5 1 CONDENSATEUR INTERNE ANTICORODAL 40 800 840

6 1 CONTACT RF CUIVRE + DORAGE 50 200 250

7 1 SOCLE CONDENSATEUR ANTICORODAL 35 200 235

8 1 GUIDE D' ONDE ANTICORODAL 300 2000 2300

9 1 BONCHON GUIDE D' ONDE ANTICORODAL 35 200 235

10 1 SOCLE BODY ANTICORODAL 35 200 235

11 1 JOINT RF CUIVRE + DORAGE 0

12 1 COLLET SUPERIEUR CUIVRE FORGE 800 1600 2400

13 1 CERAMIQUE OXYDE D'ALUMINE 800 2000 2800

14 1 COLLET INFERIEUR CUIVRE FORGE 700 1600 2300

15 1 BODY CUIVRE 1800 2000 3800

16 1 BRIDE SUPERIEUR BODY INOX 90 400 490

17 1 BRIDE JAUGE A VIDE INOX 116 400 516

18 1 JAUGE A VIDE PENNING IKR 070 900 900

19 1 BRIDE TOURNANTE BODY INOX 500 400 900

20 1 BRIDE UHV BODY INOX 500 1600 2100

21 1 BAGUE DE SERRAGE ANTENNE INOX 2 400 402

22 1 CANNE INOX 20 200 220

23 1 BAGUE DE CENTRAGE ANTENNE INOX 2 400 402

24 1 ANTENNE SUPERIEURE CUIVRE FORGE 600 1200 1800

25 1 TUBE ANTENNE CUIVRE FORGE 2000 1200 3200

26 1 BOUCHON ANTENNE CUIVRE FORGE 50 200 250

Total 10535 19200 29735


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Mass production

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Coaxial water cooled

Coaxialair cooled

CylindricalAir cooled

Unit prototype price: Coupler 53 kCHF 27 kCHF 30 kCHFEight bare couplers 424 kCHF 216 kCHF 240 kCHFUnit price: Double walled tube 15 kCHF 15 kCHF 15 kCHFUnit price: Coupling box 25 kCHF 25 kCHF 25 kCHFUnit price: Miscellaneous (clean room, leak detections, bake out, transports, …)

15 kCHF 15 kCHF 15 kCHF

Eight peripherals 340 kCHF 340 kCHF 340 kCHF

Eight couplers (+ 2 spare ceramics) 775 kCHF 550 kCHF 600 kCHF

Coupler unit price (no quantity reduction, including double walled tube 15kCHF, and Misc. 10kCHF)

78 kCHF 52 kCHF 55 kCHF

275 couplers(no test cavities, no conditioning process)

21’500 kCHF 14’500 kCHF 15’000 kCHF

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ID Task Name

1

2 Design

3 Execution Drawings

4

5 Purchasing of CERN prototype ceramics

6 Coaxial air cooled coupler

7 Cylindrical air cooled coupler

8

9 Double walled tube Execution drawings

10 Double walled tube Construction

11

12 Tests Cavities Execution drawings

13 Tests cavities Construction

14

15 Prototypes Assembly + Bake out

16 Prototypes Conditioning and Tests

17

18 Series construction (for 8 + 2 couplers total)

19 Series bake out and conditioning

Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May JunQtr 4, 2009 Qtr 1, 2010 Qtr 2, 2010 Qtr 3, 2010 Qtr 4, 2010 Qtr 1, 2011 Qtr 2, 2011 Qtr 3, 2011 Qtr 4, 2011 Qtr 1, 2012 Qtr 2, 2012 Qtr 3, 2012 Qtr 4, 2012 Qtr 1, 2013 Qtr 2, 2013

New proposed schedule

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Confirm the Saclay test stand availability in 2011:February and end of year?

Integrate advice and launch as soon as possible: One pair of coaxial air cooled window One pair of cylindrical air cooled

window

Have 2 pairs ready for tests beginning 2011

Decide which ones to construct in March 2011 (still three possible choices)

Construct remaining couplers in 2011

Have 8 fully ready and conditioned couplers beginning 2012

Today: coupler review

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Conclusion: still a lot to do…

Eight couplers could be ready within two years: Necessarily based on

existing designs and very well known processes

Coaxial air cooled and cylindrical air cooled versions to be tried: Potentially inexpensive

for mass production Interesting for large

machines

Keep the coaxial water cooled option open: Study the modification

of the cooling from water to air

Redesign the waveguide transition for: Less stress to the

ceramic Easier DC biasing

16/03/2010


Many thanks for your patience

16/03/2010

SPL power coupler

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