engineering perspectives on quadrants (2) clic09 workshop kek y.higashi
DESCRIPTION
Engineering Perspectives on Quadrants (2) CLIC09 Workshop KEK Y.Higashi. Contents. Dark current characteristics on the KEK quadrants structure experiment Surface treatment for dark current/EFE mitigation Material FANUC Co. fabrication method proposal (tentative) Assembly envelopments. - PowerPoint PPT PresentationTRANSCRIPT
CLIC09 WG4 RF Structure 1
Engineering Perspectives on Quadrants (2)
CLIC09 Workshop
KEKY.Higashi
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
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?
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
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
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
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
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?
CLIC09 WG4 RF Structure 9
Roughness: 3.3nm (PV)
Field enhancement occurs?
CLIC09 WG4 RF Structure 10
Leak rate: < 1.7e-11Pal/secIP (Semicon grade) Rinse (50degC)
Degreasing
Assembly: Class 100
No vacuum leak was found
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
CLIC09 WG4 RF Structure 12
Material
Should be Considered High Gradient Test Results of Single Cell SW Structures
CLIC09 WG4 RF Structure 13
FANUC Co. fabrication method proposal (tentative)
45°
230mm
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
?
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
CLIC09 WG4 RF Structure 16
CLIC09 WG4 RF Structure 17