スライド 1

Standard EP recipe at KEK

T. Saeki

KEK

Hot topics session

SRF2011

25 – 29 July 2011, Chicago

EP facility at STF/KEK

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EP bed

9-cell cavity

Automatic

OperationConsole

2nd floor

$C:\Users\motoaki sawabe\Pictures\電解研磨設備\IMG_2043.JPG$

1st floor

EP solutionreservoir tank

New EP facility at KEK was constructed in 2008,instead of old Nomura EP facility, which wasclosed in the summer of 2009.

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We had been keeping the KEK recipe established by Kenji SAITO in TRISTAN age.

Current density = 50 mA/cm2

The KEK recipe by Kenji SAITO from TRISTAN age. Current density = 50 mA/cm2

Slide from Lecture @ Nagoya Univ. by K. Saito

$D:\home\Doc\KEK\01-ILC\07-Conferences\2011\SRF2011Chicago\Presentations\Saeki\HotTopics\Temp-SaitoLecture.tif$

Slide from Lecture @ Nagoya Univ. by K. Saito

Difference between Jlab and KEKNovember 2009

JLab

KEK

EP Acid Tank

270L (Tank Capacity)

230L (EP acid volume)

2000L (Tank capacity)

1000L (EP acid volume)

EP Acid Flow Rate

5～10L/min.

Over flow pipes 15mmφ

10～20L/min.

Over flow pipes 25mmφ

EP and Water Rinsing

Atmosphere

Nitrogen

During EP: 12L/min.

During Rinsing: 13 ～20L/min.

Air

EP Acid Temp.

16 ~ 26 0C EP acid (Returnpipe)

21～34 0C Outside cavity

17～320C EP acid (Center ofCell)

28～50 0C Outside cavity

EP Voltage and Current

14 – 17 V

Current density =

20 – 30 mA/cm2

19～21V

Current density =

50 mA/cm2

Related to nice results of JLab? => Now, EP current density (Final EP) = 30 – 40 mA/cm2 at KEK

Yield rate for ILC threshold of VT (35 MV/m): 50% for recent 6 MHI cavities (1 bad cavity with only 1st VT).

EP2 (finial 20um) Recipe at KEK

Flow rate of EP electrolyte：15L/min.Current density：30 - 40mA/cm2 (Current ~200A), Voltage=15-22 VCavity rotation speed：1rpmCooling: Air cooling (Outer surface of cavity<350C)

After EP voltage turned off (V=0).EP electrolyte rinse with cavity rotation: 3rpm. 20min.Draining of EP electrolyte

Vertical position: 5min.　Horizontal position: 2min. Vertical position: 2min.

(Purging with N2 gas）

UPW filling and draining (rinse)UPW+PW(flow rate : 25-27 L/min) with vibrator

Water should reach the top of cavity for 20min.Additional PW running rinse reaching top of cavity (20L/min) with vibratorSub-total, 60min.PW　Filling 10min. Draining 3min.Repeat　for 30min.Total　90min.

Disassembly of setup and low pressure UPW rinseFlange and HOM cap/antenna, beam-pipes: Brushing with 2% FM-20 detergentDetergent rinse of cavity with 2% FM-20 at 50 0C (60 min.)Disassembly and low pressure UPW rinse and HPR

EP1(bulk 100um) recipe at KEK

Flow rate of EP electrolyte：15L/min.Current density：45 - 50mA/cm2, Voltage=18-22 VCavity rotation：1rpmCooling： Air cooling

After V=0EP electrolyte rinse with cavity rotation: 3rpm. 20min.Draining of EP electrolyteVertical position 5min.　Horizontal position 2min. Vertical position 2min.

(Purging with N2 gas)

UPW Filling　10min.　　　 Draining 3min.Repeat for 60min.Disassembly and low pressure UPW rinse

Detergent rinse2%FM-20 at 50 0C for 60min.Disassembly of setup and HPR SettingHPR

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EP parameters at KEK (June 2010 – July 2011)

Final EP (~20 um) for 9-cell cavities

Current density = 30 – 40 mA/cm2

T of acid inside cavity= 23 – 31 0C

Voltage = 15 – 22 V

Nb concentration (g/L)

$D:\home\Doc\KEK\01-ILC\07-Conferences\2011\SRF2011Chicago\Presentations\Saeki\HotTopics\45～50電流密度と電圧.jpg$

EP parameters at KEK (June 2010 – July 2011)

Bulk EP (~100 um) for 9-cell cavities

Current density = 45 – 50 mA/cm2

T of acid inside cavity= 30 – 40 0C

Voltage = 18 – 22 V

Nb concentration (g/L)

Experiment by Saclay

Nb sample anode

Moving shaft

Aluminum plate coveredby Teflon tape

EP acid

Bolt to connect shaft and Al plate

Bolt to connect Nb sample and Al plate

EP with Nb sample in laboratory

Labo-EP setup at KEK

$D:\home\写真\ILC\ILC2009\20090811Nomura\DSC08122.JPG$

Aluminumcathode

Reduction Reactions at the Cathode

Reduction of H+: 2 H+ + 2 e- → H2 (Predominant)

Reduction of SO42-: SO42- + 8H+ + 6e- → S + 4H2O

Does a cathodic overpotential lead to an increasedsulfur generation?

→Two Niobium samples electro-polished at 5V and 20V for a similarheavy removal with 1-9-1 (HF-H2SO4-H2O) Mixture

Sample A, 20 Volts:

9.18g removed

51 hours EP

Sample B, 5 Volts:

9.11g removed

115 hours EP

= Theoretical way to reduce Sulfur Contamination (investigation ongoing)

TEST OF LOW VOLTAGE EP (5V) AT SACLAY TO REDUCE SULFURCONTAMINATION

Experiment at Saclay

Slide by F. Eozenou

TEST OF LOW VOLTAGE EP (5V) TO REDUCE SULFURCONTAMINATION

SULFUR FOUND IN THE EP MIXTURE (200mL) AFTERTREATMENTS OF SAMPLES A AND B.

SULFUR EXTRACTED WITH CHLOROFORM:

Sample

A (20 V)

B (5V)

1st Rinse

4.5mg

2.6-2.7mg

2d Rinse

1.2-1.3mg

0.9-1.2mg

Experiment at Saclay

Slide by F. Eozenou

Backup slidesif we have time

Rinse Effect to RemoveSulfur precipitation/contamination

U.P.W.ultrasonic rinse

Ethanolrinse(vibration)

Ethanolultrasonicrinse

Detergent

FM-550

2 %

Detergent

FM-550

5 %

Detergent

FM-550

10 %

Detergent

FM-550

20 %

CleaningResult

△

○

△

○

$C:\Users\motoaki sawabe\Pictures\20090128Gas Bagのｲｵｳ\実験No.5(アルコールリンス)\ｴﾀﾉｰﾙ・超音波洗浄後(2)Small.jpg$

$C:\Users\motoaki sawabe\Pictures\20090128Gas Bagのｲｵｳ\実験No.5(アルコールリンス)\⑤前(8)Small.jpg$

Before rinse

After rinse

$C:\Users\motoaki sawabe\Pictures\20090128Gas Bagのｲｵｳ\実験No.1(超音波洗浄)\090130実験前(1)Small.jpg$

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Many whitedots are sulfurcontamination

Ethanol ultrasonic rinse

FM-550 (>10%) rinse

$C:\Users\motoaki sawabe\Pictures\20090128Gas Bagのｲｵｳ\実験No.4(脱脂剤。濃度変化)\④洗浄後(10)Small.jpg$

$C:\Users\motoaki sawabe\Pictures\20090128Gas Bagのｲｵｳ\実験No.1(超音波洗浄)\090203実験後(11)Small.jpg$

Sulfur removed

U.P.W. ultrasonic rinse

Teflon texture

Results of rinse effect tests

•Test of FM-20 (LION detergent) and 10% H2O2

•Test of Ethanol and FM-550 (LION detergent)

U.P.W.ultrasonic rinse

Ethanol

vibration

rinse

Ethanolultrasonicrinse

Detergent

FM-550

2 %

Detergent

FM-550

5 %

Detergent

FM-550

10 %

Detergent

FM-550

20 %

CleaningResult

△

○

△

○

Detergent

FM-20

2 %

Detergent

FM-20

5 %

Detergent

FM-20

10 %

10% H2O2

Cleaning Result

○

×or△

JLab Nb sample with artificial pits

$D:\home\Doc\KEK\ILC\S0study\KEK-CavitySurfaceStudy\Materials\LaserMicroScope\2008SepToOct-JLabPitSamples\JLab-Nb-sample1-w-pits\Nb-sample-w-pit-CP31um\50times-pit3.jpg$

BCP (30um)

$D:\home\Doc\KEK\ILC\S0study\KEK-CavitySurfaceStudy\Materials\LaserMicroScope\2008SepToOct-JLabPitSamples\JLab-Nb-sample1-w-pits\Nb-sample-w-pit-EP30um\50times-pit3.jpg$

EP (30um)

$D:\home\Doc\KEK\ILC\S0study\KEK-CavitySurfaceStudy\Materials\LaserMicroScope\2008SepToOct-JLabPitSamples\JLab-Nb-sample1-w-pits\Nb-sample-w-pit-EP60um\50times-pit3.jpg$

EP (60um)

$D:\home\Doc\KEK\ILC\S0study\KEK-CavitySurfaceStudy\Materials\LaserMicroScope\2008SepToOct-JLabPitSamples\JLab-Nb-sample1-w-pits\Nb-sample-w-pit-EP90um\50times-pit3-2.jpg$

EP (90um)

$D:\home\Doc\KEK\ILC\S0study\KEK-CavitySurfaceStudy\Materials\LaserMicroScope\2008SepToOct-JLabPitSamples\JLab-Nb-sample1-w-pits\Nb-sample-w-pit-EP120um\50times-pit3.jpg$

$D:\home\Doc\KEK\ILC\S0study\KEK-CavitySurfaceStudy\Materials\LaserMicroScope\2008SepToOct-JLabPitSamples\JLab-Nb-sample1-w-pits\Nb-sample-w-pits-AsRecvd\50times-pit3.jpg$

As received

Pit3

EP (120um)

After BCP(30um)+EP(120um), still the edge of pit is sharp!

Large steps at grain-boundaries after BCP.

40 um

Nb sample anode

Moving shaft

Aluminum plate coveredby Teflon tape

EP acid

Bolt to connect shaft and Al plate

Bolt to connect Nb sample and Al plate

EP with Nb sample in laboratory

Labo-EP setup at KEK

$D:\home\写真\ILC\ILC2009\20090811Nomura\DSC08122.JPG$

Aluminumcathode