LARP Phase II Secondary Collimator RC-1

LARP LHC PHASE II COLL RC1 - S. Lundgren 1 April 2009 No 1 /6n

LARP Phase II Secondary Collimator RC-1

Collimator Design Review

01/04/09


Introductory Statements

Your comments and/or questions are welcome at any time . There will also be time

at the end for an in-depth discussion of any and all aspects of our design.

Sub-title of this talk :

“The Rotatable Collimator from the inside out”

Basic format I hope to follow:

• Internal component detail (CAD models and photos of real pieces (RC-0 / RC-1)

• Fabrication photos of components of the RC-0 Jaw aka Heater test Jaw.

• Fabrication photos of some of the RC-1 components that are currently in work.

• Specifications and physics requirements and how we meet them.


Collimator Jaw-Hub-Shaft Concept

Jaw heats up along the side facing the beam and lengthens causingeach end to deflect away from the beam and into the 2mm annular gapbetween the Shaft and the Jaw.The Jaw also swells a bit causing the Jaw face move towards the beam.


Some Calculations

Jaw heating and deflection characteristics for

Steady State (SS) and Transient (TR) conditions

Component SS TR units

Max jaw temp 70.6 224 C

Max deflection toward beam 105 365 μ m

Surface Sagitta 226 880 μ m

Effective length 0.67 0.33 m

Water temp rise 20.3 C

Water pressure drop 2.4 bar


Cutaway of Jaw Assembly


RC-1 Half Shaft and Hub Assembly

Inner Keeper RingForces moly inner fingers to keep up with Glidcop expansion during brazing

Outer Keeper RingKeeps moly outer finger tipsfrom splaying out and away from Glidcop during brazing

Cu-Au alloybraze wire

This Outer Keeper Ringis machined off after brazing in order for Shaftto pass through Mandrel ID

This Outer KeeperRing acts as a stop to position the Shaftlongitudinally


RC-1 Molybdenum Shafts


Details of Ends of Molybdenum Half Shaft


RC-1 Hollow Glidcop Hub (prior to Cu plating & grooving)


Grooving details of Glidcop Hub


RC-0 Half Shaft and Half Hub Brazing

The two Half Hubs are now one. We originallyneeded to machine outa copper inner keeper plugthat forced the molyfingers out with the Glidcop during brazingto provide an opening for the tubing.RC-1 uses a thinner SSTring that can remain inside the Shaft with room for the tubes to passthrough.


Mandrel with Cooling Tube


RC-0 Mandrel at QC


RC-1 Mandrel in work


RC-1 Mandrel almost finished (March 15th)


No Vacuum to Water Joints

Tubing is wound into Mandrel groove while free ends pass through the hollow center parallel to each other yet exiting on Shaft centerline. When Collimator rotates the tubes twist on their own axis but not around each other.


Tubing coil on turntable for winding

16m of tubing are removed from “loose coils”and placed on a turntable for payout.


Winding tubing on the RC-0 Mandrel


Nearing the end or… forming the bend


RC-0 Mandrel Brazing Setup


Machining the RC-0 Mandrel to size


Collimator Jaw Brazed to Mandrel

•RC-1 Jaw has 5 cylindrical sections.•End sections are tapered.•RC-0 has 16 quarter sections, none are tapered.•The RC-0 Jaw to Mandrel fit up for brazing was quite time consuming & expensive.•Each quarter section had to be reworked to fit Mandrel final diameter!•Changing to full cylinders, to save time & cost, meant they should be a somewhat shorter to be easier to slide over the Mandrel with the tight brazing tolerances.•Robustness test will use 1 RC-0 and 1 RC-1 style Jaw


16 Jaw Quarters with Cu/Au alloy foils


Jaw Braze preps continue


RC-0 Jaw Brazing Success


RC-1 Jaw braze Assembly


Section of Revised Jaw

Cu-Au braze wirego here ~ 40 snaprings

Braze wires replace foils simplifyingbraze preps


RC-1 Final Machining


20 Facets 20 years?

20.25mm

Thickness of Glidcop Jaw (facet to water) is 24.5mm.

~15 degree taper at each end places RF contact bearings ~10mm away from facet.Facet length = 930mm (oal) – 2x38mm (taper) = 854mmTaper may be too generous and could be shortened for a longer facet.


Facet Flatness

Flatness Specification is 25 microns over full length of Jaw.

How did we do?

How we can do even better!


Jaw Facet Preliminary measurement for end-to- end flatness


Up Beam end Jaw Support Version 1

Diaphragm allows Jaw end-to-end offset and Shaft sag.Flex vanes compensate (along with the diaphragm) for Shaft expansion


Jaw Support Development

A few thoughts:

Rigid mount would hold drive gearing in alignment with Shaft.This would require a flexible connection to the shaft to allow for deflection (sag)

due to gravity and Jaw end-to-end offset.Or a spherical bearing. At the time we were unable to locate a full complement

ceramic spherical bearing set.So… A diaphragm was introduced to attach the gear to the Shaft.This diaphragm, if designed correctly, should be able to distort not only for the

angles but for the change in length of the Shaft due to thermal effects. Eventually it was determined that the End Support would need to flex to help the

diaphragm absorb the longitudinal expansion. Version 1 was designed.Finally the current version combines the diaphragm angular distortions with the

flexibility of the original End Support.The final hurdle is to find an acceptable high strength stainless steel to fabricate

it from.


Up Beam Jaw Support Current Version


Down Beam Jaw Support Current Version

100 1 mm dia. ceramic ball bearings roll betweenthese two races


Cutaway of Jam Nut and Support

Jam Nuts mate at beveled surfaces to strengthen tip of Support

Rotation Mechanism mountsto tab on bearing race

100 1mm dia. Ball bearings roll in “V” groove


Outboard Bearing Race/Axle

Buttress Threads

100 1mm ceramicball bearings roll here


Inboard Bearing Race w/gear Drive mounting tab

Bearings roll here


Jam Nut

Two of these lock Collimator Jaw to the End Support


Shaft Ends are grooved for ceramic ball bearings

Ceramic bearings roll here and at far end


Shaft End bearing groove details

Bearings roll here


Jaw End Support System w/cooling tube

(Bellows removed to show support detail)

Flexible support is high strength stainless steelwelded to bottom ofbellows cuff at assembly to Tank Base Plate

Jaw Shaft End rests in slot of Support and is held by jam nuts on either side

~100 1mm dia. ball bearings in End adapter for rotation

Bellows mounting to Drive is unchanged from CERN design

Cooling tube adapter is tig welded after Jaw is installed in Tank

“Beefed-up” design still permits Jaw end-to-end offsets (3mm), Shaft thermal expansion and static sag. Deflection is improved for non-horizontal collimator positions.


Jaw Rotator/Gear Drive Accuracy

Jaw face alignment specification dictates an indexing type of mechanism. This drive allows up to 8 mis-counts of drive motor steps before Jaw moves off position.

2x1 bevel reduction in combination with 80 x1 worm reduces side load on drive and support to a minimum level.

Worm also provides locking of Jaw.Backlash is a minimized due to tubing

torque load


Indexing the Collimator Jaw

Indexing can be 1 facet, 5 facets for 90 degrees, 10 facets for 180 degrees.

For a distortion of Jaw in the plane of the beam a 90 degree advance would render the distortion a non-problem.

After a 180 degree advance a subsequent hit might correct the distortion, if a were of the same magnitude.

Following a sequence of 10 facets (180 degrees), 1 facet then 10 facets, a total of 5.25 twists of the tubing would be needed to “use up” all 20 facets.

Tubing was twisted an equivalent of 8 times. No visible defects observed.


Twisted Hollow Copper 10mm x 7mm


Ratchet actuation conceptual arrangement

Hammer contactshere duringover-travel of Jaw

Wire Springs restore Hammer after ratchet movement


Jaw End Details for Image Current connection

300 Rhodium Plated stainless steel ball bearings roll here

Bearing racesfit in recesshere


Image Current Bearing Race (example)

GlidcopRing details are similar for both races


Image Current Foil Assembly Version 1

Height of parts was necessary to shadow the Gear Drive on top of Jaw End Support

This surface mounts to bearing race


Current Version of Foil Assembly

Temp sensor mounts here

Reduced heightof foil is minimum to shadow “Geneva”


Temperature Sensor/ Image Current Foil mount

Foil Brazes Here

Temp Sensor mounts here

Mounts to Bearing Racehere


Current Version of Image Current Foil

1mm x 40mm Glidcop foil will be life cycle deflection tested

This end curves to conforms to Mountfor brazing

This end curves toconform and attachesto Beam pipe Flange ID


Preliminary Tank concept

First transition from roundpipe to square geometry is machinedinto the flange end of tank. Flexible Glidcopfoils (not shown) carry image current to second transition which tapers meet Jaw end.

Tank has tapered featuresto prevent upsetting the image current


New Cylindrical Tank Concept


Why the change?

We were interested in the ability to work on the image current components after things were welded up because we may not get it right the first time.

Results from preliminary laboratory RF tests showed that geometry to be less an issue than previously anticipated so the more complicated transitions may not be needed.

We will be hand tig welding the tank together rather than e-beam welding so distortion could be less of an issue.

Pluses:Uses standard pipe.Thinner wall results in less radiation effects.Camera ports for viewing the Jaw face remotely seem a bit simpler to implement.

Minuses:However, HOM modeling has recently shown high heating loads (larger volume).Until those issues are resolved this configuration might only be useful for the

TT60 tests.


Cylindrical Tank body

Tank is 355.6mm diameter x 6.35mm wall welded pipeMaterial is 304 SST. Note: Weld seam will be eliminated by cutout at bottom.


Base Plate

Base Plate is only slightly larger than CERN design


End Flange

End Flange reduces the Tank dia to a DN250 CF FlangeMaterial is 304LN, if required, otherwise 304L


Beam Pipe Adapter

End Flange reduces the DN250 CF Flange to DN100 Beam pipe FlangeMaterial is 304LN, if required, otherwise 304L.Note: Small hole is for the Camera Viewport Nipple


Assembling the Tank for welding

End Flanges could be tackwelded to cylinder first

Fixturing holds Cylinder rigidTo retain shape during welding

Collimators were previously assembled to Base Plate and welded into bellows end cuff

All viewports are previously welded in


Proposed TT60 Robustness Test Configuration

• Preferred orientation is 0 degrees.• RC-0 & RC-1 Jaws are used.• Collimator mounts on CERN stand.

– Cooling water quick connect?– Cables do not?

• Laser micrometers mount herefor measuring possible permanentdistortion after beam strike

• End ports are 1mm thick titanium.

• Vacuum pump (if needed) mounts to tee at down beam end.

• Chain tensioners used on all flanges.

Cameras mount here (both ends) for remote viewing surface damage to RC-1 Jaw after beam strike

Beam

DN250 flanges at ends permit access prior to test and after “cool-down period”


Bonus Slide

Documents

LARP Phase II Secondary Collimator RC-1