Cell to cell alignment on GLC structures

Cell to cell alignment on GLC structures

24 Nov. 2014, CERNToshi Higo (KEK)

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Contents

Transition from GLC/NLC to CLIC

Alignment targetAlignment mechanismMachining

Stacking/assemblyBookshelfRotation alignment

Bonding/brazing

Bending

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Succeeding the technology

of GLC/NLC to CLICGLC/NLC :

Targeting longer with wake field control

CLIC: F

ocus to date

on high-gradient

Disk fabrication

(KEK)

Bonding (SLAC)

CP (SLAC)

VAC bake (SLAC)

High power test

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CLIC Structure Review

Key technologies are in

hand in early 2000

except for proof

of high gradient

RDDS1

KX01

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CLIC Structure Review

Precision machined

Aligned to V-block

Pre-bonding

with V-block

Diffusion bonding

Precision brazing

Straightening

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CLIC Structure Review

Quick glance at GLC/NLC

Target alignment tolerance

Cell-to-cell

alignmentA micron-level

Bookshelving100

microradian

Bending over a structure

10 micron level

Can be corrected after bonding, as long as low-order

smooth bow

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Alignment mechanism

Disk stackingBest withOutside diameter + reference V-block

Short-stack based or long-stack at onceOthersAlignment pin, Self

fitting Less precise and worry about sticking during bondingQuad or half

Few

experience

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Alignment mechanisms

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Self fitting for several micron

Need care to keep stack

Quad / Half

several to

10μm?

S

tacking by

a

robot PSI How well?

P. Craievich

Swiss FEL

HG 2013 Trieste

OD and V-block for one micron level

Start with precision machining

Outside

diameter  R

Used for alignment with respect to beam axis

Reference for radial direction of

cell

shapeCan

be realized with proper turningChuck face self cut

 Z

Mating surface flatness

Reference for

axial direction

of cell

shapeOther complex shape

Relative positioning accuracy in milling can be within a micron level unless re-chucking

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Start with precision machined cells

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Keys

are

Outside diameter

Flatness

Both sides w.r.t. OD

Parallelicity

Notch for rotation

Precision machining

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CLIC Structure Review

OD can easily and robustly be measured.

Axial position can well be set by self cutting.

Stacking/assembly

Stacking disks

OD referenceRemoving air gap between disksRotational alignment by mark or key

Alignment preservation until bonding processDuring transportation

Keep with pushing to reference surfaces

Pre-bonding as needed

with pushing

to reference surfaceSuppress mutual sliding by friction with axial force by bolts running through the stack

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SLAC: Start with short-stack bonding

Easy handling size

1—2 feet

Full-stacked on V-block to confirm RF property

Straightforward to check RF

Difficult

handling for

>1m

1.3m stacking to bonding in 1996

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Hand

stacking w.r.t. V-block

checked

by

Microsense

Extraction from stack jig

Moving to furnace

DB and braze

Cell alignment measured by gap sensors

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Gap

between

sensor and reference V-block

Can m

easure cell

offset and

inclination

Vertical stack of

f80 and 1.3m followed by diffusion bonding at 800 C

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Vertical s

tack followed by 800

degC

diffusion bonding

Cell-to-cell kept at

5

microns

Bow changes 10 microns in smooth manner

Bow of

several 10

microns

Stacking followed by bonding at 900C for IHD1

f80mm, 1.3m

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Cell stacking of IHD1

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Cell stacking and bonding

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Chose 60

deg

s

tack

Diffusion bonding at

900

degC

Deviation from V-block by several microns

Kink was not easy be corrected

Bow of 10 microns

Cell alignment result of IHD1

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Cell-to-cell alignment was good;

s

<1 micron

Evolution

toward 1.8m fabrication

Cleanroom to be fre

e from dust migrationPrecise setting of base for stackingprecision V-block with fixed plane perpendicular to the V-block

Careful stacking with

Microsenses

to check floating from V

Autocollimator to check bookshelf and manual feedback to minimize assumed air gap

Pre-bonding to freeze

the mutual movement of

cells

at 150degC,

2.6MPa for 1 day with V-block

Diffusion bondingIn vacuum furnace

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f

45/f60 1.8m stack with pre-bonding (PB)

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Rotation on furnace base

Move 800km s

itting on V-block

DB in

vac

furnace

Stack in cleanroom

RDDS1 stacking with

two

M

icrosenses

1.8m DDS, RDDS, HDDS, …. made at IHI in

~1998Precision stacking and pre-bonding

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Stacking

Pre-bonding

Cleaning

Improved cell-to-cell alignmen

t in DDS3 and RDDS1

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Cell-to-cell within 1 microns,

s

<1micron

RDDS1 after DB

Smooth cell-to-cell but very big bow

Proof of wake field suppression in RDDS1

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CLIC Structure Review

Precision cell

Stacking + PB

DB and shipping

to SLAC

Brazing

ASSET

Wake

field confirmed

Alignment

confirmed

Bookshelf, rotation and bow

Bookshelf

Until now we do not have any definite idea We just try the air gap as small as possible

Parallelicity between two flat surfacesOD perpendicular to the both surfaces

Check this OD profile with gap sensors running along beam axis

Rotation

Mechanical reference, such as notch

Inscribed line by seeing optical deviceRobotic

stackingBow

Smooth bow can bee corrected later.

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Less-friction smooth jig

to press end surface during DB

For less sticking

with copperAlumina ceramics



stick and make flare

Graphite

 worry about fragileGlassy carbon

 goodGlass-like carbon coat GLASTIX KOTE

 seems

good

Preserve good end surface

Needed for further assembly with good alignment

GLC/NLC used sheet brazing but not good from alignment point of view

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Care should be made on DB end

surfacesto connect additional parts further

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Alumina ceramics

　→　

Graphite

Scratch

　　→　

Si

3N

4　3元系、

900℃　→　sticking and makes flare

　　　→　Glassy Carbon

After DB

Graphite

Correction of flare

Glassy carbon

Conclusio

n

Cells can be stacked w.r.t. mechanical reference with using

outside diameter.Cell alignment can be kept without slippage while handling,

solid-phase bonding

process.

One

micron-level cell-to-cell alignment

is feasible through man-made process.

Further mounting of beam-line

parts on the bonded main body needs care on

end surface quality

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