Engineering Perspectives on Quadrants (2) CLIC09 Workshop KEK Y.Higashi
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Transcript of Engineering Perspectives on Quadrants (2) CLIC09 Workshop KEK Y.Higashi
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CLIC09 WG4 RF Structure 1
Engineering Perspectives on Quadrants (2)
CLIC09 Workshop
KEKY.Higashi
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CLIC09 WG4 RF Structure 2
Contents
1. Dark current characteristics on the KEK quadrants structure experiment
2. Surface treatment for dark current/EFE mitigation
3. Material
4. FANUC Co. fabrication method proposal (tentative)
5. Assembly envelopments
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CLIC09 WG4 RF Structure 3
Notice: Deformed cavity wall
Cell 3(×35)
Cell 3(×100)
Cell3 deformation: 0.053mm
32009/10/12
KEK’s version: 50 micron chamfer
Roughness: ~ 5 micron order?
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CLIC09 WG4 RF Structure 4
QMS (1) :RF Power and gasesPressure of H2 dominated. Pressure of water is inactive.
21828
44
RF Power into Acc
ACC Chamber CCG
10-8
10-7
10-6
10-5
0.0001
Pre
ssure
(Pa)
Dark current characteristics on the KEK quadrants structure
~x1000 higher than T18 structure -> Detail is talk by Higo
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CLIC09 WG4 RF Structure 5
Enhanced Field Emission/Dark current(Reference :J. Wang, G. loew)
These can be classified into various categories;
(a) Metallic surface roughness due to imperfect machining, scratches, micro protrusions, “tip-on-tip” productions
(b) Metallic dust, micro particles
(c) Grain boundaries
(d) Molten craters after breakdown
(e) Dielectric impurities and layers
(f) Absorbed gas
(g) Metal-insulator-vacuum (MIV) or metal-insulator-metal (MIM) layers
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CLIC09 WG4 RF Structure 6
Surface treatment for dark current/EFE mitigation
-5 10-7
0
5 10-7
1 10-6
1.5 10-6
0
200
400
600
800
1000
0 2000 4000 6000 8000 1 104 1.2 104
etchingdaiamond1High press1Vacuum1oil-less1Hydrogen1
Temperature C)( ゚
Time (s)
Out gas characteristics on various treatment of OFC
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CLIC09 WG4 RF Structure 7
Field Emission Microscope
-210-6
-110-6
0
110-6
210-6-210-6
-110-6
0
110-6
210-6
051071108
1.5 108210
8
-210-6
-110-6
0
110-6
210-6
50nm
nAPotential: 20V, Resistance: 100 Ohm
0
5 105
1 106
1.5 106
0 2 107
4 107
6 107
8 107
1 108
1.2 108
Calcuration of field emission090908
Current density(A)
V/m
Check Grain boundaries, impurity, material defect, roughness
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CLIC09 WG4 RF Structure 8
Ultra High-Precision Diamond Tuning Surface of Copper
Class1
60mm Diameter, 6mm thickness
Contacted region
Inner diameter 35mm
PV: 21nm PV: 13nm
Enough quality as metal-metal contact for Quadrants?
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CLIC09 WG4 RF Structure 9
Roughness: 3.3nm (PV)
Field enhancement occurs?
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CLIC09 WG4 RF Structure 10
Leak rate: < 1.7e-11Pal/secIP (Semicon grade) Rinse (50degC)
Degreasing
Assembly: Class 100
No vacuum leak was found
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CLIC09 WG4 RF Structure 11
Surface Treatment for Quadrants • Pre-machining (remain 100 m)• 650 degC annealing• Final machining (same surface roughness to dis
k)• Chemical Etching (~5 m)• HPWR (remove burs, particle)• Degreasing (remove particle and fine oxide laye
r)• 150~200 degC baking in vacuum• Assembly in the ILC grade clean room
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CLIC09 WG4 RF Structure 12
Material
Should be Considered High Gradient Test Results of Single Cell SW Structures
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CLIC09 WG4 RF Structure 13
FANUC Co. fabrication method proposal (tentative)
45°
230mm
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CLIC09 WG4 RF Structure 14
Cost Estimation (very rough)TD18 structure Unit is MYen
Disk Type Quadrants
Material
Whole fabrication 2.5 2.8
Vacuum chamber - 1.0
Surface treatment 0.5 0.3
Bonding (Assembly) 1.5 0.5
RF Tuning 0 (eventually) 0 (eventually)
Absorber
Baking 0.5 0.5
Instauration
Alignment
Total
?
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CLIC09 WG4 RF Structure 15
Summary
1.One order more precise machining (roughness, dimension) technologies glowed up compare to NLC/GLC generation, So Quadrants is very attractive
2. 5000~7000 disks, 25~30 structures fabricated for NLC/GLC
3. In order to understand fabrication technologies for high gradient quadrants structures, may be needed 2~3 years
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CLIC09 WG4 RF Structure 16
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CLIC09 WG4 RF Structure 17