Download - Cavity Fabrication Status in KEK/CFF
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Cavity Fabrication Status in KEK/CFF
Takeshi DOHMAE
2018/10/25
International Workshop on Future Linear Colliders (LCWS2018)
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Current status of Cavity Fabrication Facility (CFF)
Cavity Fabrication Facility (CFF) is working for ILC project;
• Study for cost reduction in cavity fabricationMass production techniques
Try new materials (LINAC2018 THPO002)
• Pass the helium vessel code (high pressure gas safety act.)Buckling simulation
Welding Procedure Specification
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Main equipments in CFF
EB welding machine(SST, Germany)Max. beam voltage: 150 kV
Servo press machine(AMADA, Japan)Max. applying force:1500 kN
Chemical polishiing
CNC vertival lathe(Moriseiki, Japan)
Microscope(Surface inspection)
A cavity can be manufacturedin KEK site combined with machine tools at MEC
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History of CFF
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3×9-cell cavities, 5×3-cell cavity, 10× 1-cell cavities(& some seamless cavities)
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Cost reduction study
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Motivation in cavity fabrication facility (CFF)
• To realize the ILC project, a cost reduction is imperative issue
• From view point of cavity fabrication:
Establish mass production techniques.
Reduce material cost w/ keeping performance.Low purity Nb (low RRR Nb)
High Ta contained Nb:
Low Ta contained Nb is expensive due to special
chemical treatment
Large grain Nb:
Forge & rolling process is skipped
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We tried two kind of Nb as the cavity material
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Eacc [MV/m]
Pi (2K, 1st)
Pi (2K, 2nd)
X-ray, Pi (2K, 1st)
X-ray, Pi (2K, 2nd)
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X-ray, Pi (2K, 1st)
Material 1: Low RRR, high Ta contained Nb
Cavity1 Cavity2
100μm EP・ 750deg×3hrs annealing 20-30μm EP ・ 120deg×48hrs baking
Beam tube Cell
Stiffener
☆Start material: Nb ingot from CBMMBeam tube: Forged into seamless tubes by ULVACStiffener rings: Forged and rolled into sheet by ULVACCell: Melted 2 times (normally ~5 times), forged and rolled
RRR
Start material 60~108
After 2 melting (ingot) 277~298
Nb sheet used for cell 293
ILC requirement
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Material 2: Mid RRR, high Ta contained, LG
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Beam tube Cell
Stiffener
• Beam tube: Low RRR (< 100), high Ta contained (same as previous cavity)• Cell: Mid RRR, high Ta contained large grain (LG) Nb
→ Forge and rolling process were skipped (cost reduction)RRR=242~298
• Stiffener: Recycled Nb (melted, forged and rolled by ULVAC)
LG Nb (φ260)
Two 3-cell cavities (Tesla-like shape) are fabricated using these materials
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Eacc[MV/m]
Pi (2K, 1st)
Pi (2K, 2nd)
x-ray, Pi (2K,1st)
x-ray, Pi (2K, 2nd)
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Eacc [MV/m]
R10 VT2 (2K, 1st)
R10 VT2 (2K, 2nd)
Material 2: Performance test results
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Cavity1 Cavity2
@2K, π-mode Q0, max Eacc, max [MV/m] Rs [nΩ] Mag. field* [mG]
Cavity1 (VT2) 2.22×1010 36 4.19 -0.1 ~ 2.5**
Cavity2 1.87×1010 42 (40 in final) 7.15 5.9 ~ 7.8
*Magnetic field measured by flux gate set at 2 cell during measurement. (after superconducting transition)**Remaining mag. field was canceled by solenoid coil (< 1mG). ΔT (=temp. difference between top & bottom beam tube) ~ 30K was applied when superconducting transition.
ILC requirement
100μm EP・ 750deg×3hrs annealing 20-30μm EP ・ 120deg×48hrs baking
Cavity1: VT1 was limited at 25MV/m by quench. Defect was removed and VT2 was performed.
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Issues of LG cavity
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• Different mechanical properties. Problem in passing helium vessel code
• Large anisotropy and deformation; Problem in welding due non-uniform thickness Increase welding processes due to bad roundness at the equator
• RRR differs even in same ingot. (CBMM LG → 242~298)
Special jig for equator EBW
Non-flat equator edge after trimming
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Current status in CFF
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On going fabrication in 2018
Fabrication of 9-cell Tesla shape cavity made by LG Nb(material 2) is on going now.
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TD LG1
TD LG2
CBMM LG w/ Annealing
CBMM LG w/o Annealing
FG Average
Design value: 2mm
Still some difficulties for fabrication.
Roundness = radius difference between two concentric circle of internally and externally tangent.
Fabricated dumbbells for 9-cell cavity
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Training of new industrial company
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Stiffener rings cut by a laser beam
• Collaborating and training new company for cavity fabrication.• “MIRAPURO” is fabricating 9-cell cavity following CFF cavity
fabrication.• Innovates new techniques into cavity fabrication from their
industrial field. (laser cutting etc.) MIRAPURO
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Helium vessel code
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Aiming to pass the high pressure gas safety act. by KEK.
Several items are necessary;• Buckling simulation• Mechanical properties of materials• Thickness check after welding• Welding procedure specificationetc.
Fabricate 9-cell cavity with certification in FY 2018→load into STF
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Additional investigation
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Hydroforming cavity fabrication
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KEK is still investigating hydroforming cavities.Currently two 3-cell cavities were fabricated.
W3Completed in 2016
U6 (new!)Completed in 2017Tested in 2018
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Materials and inner surface
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5 mm
Cavity W3 U6
Nb tube Supplier
Size OD130 x ID123 (t3.5) x 800L OD138 x ID131 (t3.5) x 830L
RRR 387 353
Average roughness after EP2 Ra 8.6μm Ra 10.6μm
Inner surface after EP1 (100μm) + EP2 (30μm)
Barrel polishing was skipped before VT.
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0 5 10 15 20 25 30 35Eacc (2cell) [MV/m]
Summary of two 3-cell hydroforming cavity
KEK-W3
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Cell #1 Cell #2 Cell #3
> 26.4 MV/m 36.1 MV/m (initial)31.7 MV/m (final)
26.4 MV/m
KEK-U6
Cell #1 Cell #2 Cell #3
> 27.9 MV/m 26.7 MV/m 28.4 MV/m
1.00E+08
1.00E+09
1.00E+10
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Q0
Eacc (1, 3cell) [MV/m]
Pi (2K, 1st)
Pi (2K, 2nd)
IPAC2016@Busan
Note: All cells are center-cell shape → Not a flat fieldπ-mode
Over 25 MV/m was achieved with basic surface treatment. (w/o any special surface treatment such as barrel-polishing, local grinding)
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Summary
• Cost reduction study3-cell cavities were fabricated with different materials.Cavities made of mid-RRR, high-Ta LG meet ILC
requirement.
• Current status in CFFCavity fabrication:
Fabricating 9-cell cavity with LG.Collaborate and training with new company.
Helium vessel codeAiming to pass through the helium vessel code by KEK.Fabricate 9-cell cavity with certification.→into STF
• Hydroforming cavityOver 25MV/m was achieved with standard surface treatment recipe.
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Backup slides
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Material1: Chemical components
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C N O H Zr Ta Fe Si W Ni Mo Hf Ti S
Spec.ASTMB393*1
100 100 250 15 200 3000 100 50 500 50 200 200 300 N/A
Spec.CBMM
50 100 250 2000 50 10
Ingot*2 <30 33 26 <2 <1 1194 3 <20 <5 <1 <1 <2 7 <10
Sheet*3 <10 30 <10 1 <10 1210 <10 <10 <10 10 <10 <5
Ingot*4 <10 <10 <10 <1 <10 1430 <10 <10 <10 10 <10 <5
unit: wt ppm
*1 R04210-Type 2, Commercial grade unalloyed niobium*2 Start material, measured by CBMM*3 Low RRR, after 2nd process, measured by ULVAC*4 Medium RRR, after 2-time EB melting, measured by ULVAC
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Material2: Chemical components
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C N O H Zr Ta Fe Si W Ni Mo Hf Ti S
Spec.ASTMB393*1
30 30 40 5 100 1000 50 50 70 30 50 50 50 N/A
Ingot*2 <30 6 5 <2 1191*
3 <3 <5 1 <10
unit: wt ppm
*1 R04220-Type 5, RRR Superconducting Grade Pure Niobium*2 Start material, measured by CBMM*3 Ta content is allowed up to 1300 in spec.
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Material1: 1/T vs R
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Rs [nΩ]
cavity 1 10.0±0.4
cavity 2 9.9±0.4
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Material2: 1/T vs R
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R10 (VT1) 6.88±0.28 nΩ FG1=5.2mG, FG2=3.2mG @1.8K
R10b (VT1) 7.15±0.38 nΩ FG1=7.33, FG2=6.7mG @ 4K
R10 (VT2) 4.19±0.24 nΩ FG1=2.5mG, FG2=-0.12mG @4K
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VT setup with solenoid coil
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Date Magnetic field
R7 2017/6/14 2.3, 1.0 mG @ 290K8.3, 6.8 mG @ 4KTc; 6/14 12:40 ~ 12:50
R7b 2017/6/28 2.0, 1.5 mG @ 290K7.7, 7.4 mG @ 4KTc; 6/28 12:00 ~ 12:10
R10 (VT1) 2017/12/21 3.8, 2.5 mG @ 290K3.0, 5.0 mG @ 4KTc; 12/21 11:35 ~ 11:45
R10b 2018/2/22 6.3, 6.7 mG @ 290K7.3, 5.9 mG @ 4KTc; 2/22 11:20 ~ 11:30
R10 (VT2) 2018/4/19 5.2, 5.1 mG @ 290K2.5, -0.1 mG @ 4KTc; 4/19 9:35 ~ 9:45
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