1. Disk-damped versus Quadrant-damped from engineering view point
2nd International Collaboration Meeting
on X-Band Accelerating Structure
080513
KEK
Y.Higashi

2. Contents of engineering view point (still under studying/rough estimation)
Engineering requirements
Comparison of fabrication procedure
Comparison of machining
Material shaping characteristics
Geometrical characteristics
RF measurement/Tuning
Summary

3. Engineering requirements
@ 2a,2b /- 1micron (needs rf tuning)
@ Bookshelf < 100mradian
@ Roughness < 1 micron including
grain boundary step
@ Corner shape complete round
@ Out gas small amount
@ Vacuum level < 10-9 Torr
@ Cooling system

4. Comparison of fabrication procedure
Quadrant type Disk type
Making perpendicular shape
Rough/medium milling
*Annealing (500deg.C)
Etching
Assemble of four quadrants
rf tuning
Set into the vacuum vessel
*500deg.C baking
Instauration
In-situ baking
Slicing from bar
Rough/medium machining
Annealing (500deg.C)
Final tuning
Final milling
rf inspection each other
Etching
Bonding (cooling pipes, coupler)
rf tuning
H2 firing / 500deg.C baking
Instauration
In-situ baking
* If CuZr material is impossible?

5. Comparison of machining
Quadrant type Disk type
Diamond tuning machine/ tool
Environmental Temp. control
(+/- 0.5 deg.C)
3D Milling machine (tool positioning resolution 0.01 micron/ WC/diamond tool)
CMM (0.01 micro resolution)
Chucking tool for turning/milling
Disks stacking tool (precise V-block)
Bonding/Brazing jig
3-5D milling machine
ball end mill tool with precise profile
(1 micron tool positioning accuracy)
CMM (1 micron accuracy)
Alignment tool/ jig
Fixture of quadrants
Quadrants assembly tool
(optical microscope, CMM….)

6. Material shaping characteristics
Ball end milling Diamond Tuning
(mainly Quadrant) (mainly Disk)
Poor tool position
Tezel point
(No velocity)
Ball end mill tool
Cavity iris
Damage layer ~ 1-2 micron
Mechanical/thermal stress
Eliminate Tezel point
Simultaneous 4~5 axis control machine
Diamond tool
Can be controlled dimensions by feed forward technique
Tool wear control
Damage layer 0.1 micron

7. Geometrical characteristics
Quadrant Disk
Asymmetric shape
Cylindrical symmetric shape
Deformation due to milling
Deformation due to tuning/milling
>>
But
Depend on annealing
A point to be considered
Deformation due to stress by pulse heating?
Hard stress by milling

8. RF measurement/Tuning
　 Quadrant Disk
Only play after assembly
Can be inspect each cell

9. Summary @ Precise fabrication of Quadrant and Disk
type structure already performed.
@ Precise integration techniques of quadrant
structure still under studying.
Most important thing is breakdown characteristics
Will be discuss at tomorrow session