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LARP Phase II Secondary Collimator RC1 Prototype Engineering Status 6/21/06 - PowerPoint PPT Presentation

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LARP Phase II Secondary Collimator RC1 Prototype Engineering Status 6/21/06. Jaw-hub-shaft concept - continued Permanent deformation (elastic/plastic analysis). Overview. Review Baseline jaw Central stop Concept Discuss RC1 baseline deflection reference Refine baseline

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LARP Phase II Secondary Collimator RC1 Prototype Engineering Status 6/21/06

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LARP Phase II Secondary Collimator RC1 Prototype Engineering Status6/21/06

Jaw-hub-shaft concept - continued

Permanent deformation (elastic/plastic analysis)

2006-06-21Coll Eng E Doyle 1/18


  • Review

    • Baseline jaw

    • Central stop Concept

  • Discuss RC1 baseline deflection reference

  • Refine baseline

    • Shorter pitch cooling helix

    • Solid core

  • New jaw-hub-shaft concept

  • Eliminate central stop?

  • Plastic deformation

2006-06-21Coll Eng E Doyle 2/18

Review: Baseline Jaw Performance (deflections referred to edge of jaw - Note this is not a realistic mounting possibility)

Exceeds spec, or other possible problem as noted



Baseline: hollow Cu, 25mm wall, helical cooling - 5cm pitch

Exceeds Allowed Deflections

All temperature simulations based on 20C supply. For CERN 27C supply add 7 to all temperature results. CERN max water return temp 42C

2006-06-21Coll Eng E Doyle 3/18

Two concepts for reducing deflection

  • Central aperture stop

  • Separate shaft and jaw

2006-06-21Coll Eng E Doyle 4/18


dx=394 mm

Spec: 25mm


Bending exceeds 25um spec => Compromise:

Central aperture stop controls deflection - causes jaw to deflect away from beam – Note: this is idealized stop

Steady State operation (End supports as modeled)


  • Idealized Central Aperture Stop

  • Swelling neutrallized

  • Bending neutralized

More realistic: shaft support

-Swelling toward beam

-Bending toward beam

2006-06-21Coll Eng E Doyle 5/18

RC1 Concept as presented to reviewers: Flexible end supports with central aperture stop

Leaf springs allow jaw end motion up to 1mm away from beam

Stop prevents thermal bowing of jaws from intruding on minimum gap

Local swelling not controlled

2006-06-21Coll Eng E Doyle 6/18


Real aperture stop allows some swelling

Stop hidden out of beam’s reach at 45o

Swelling not fully neutralized – note bulge of hot region between stop and aperture.


Peak temperature due to beam heating

2006-06-21Coll Eng E Doyle 7/18

Jaw-hub-shaft - Eliminate Central Stop?




  • Hub acts as a heat sink near peak temperature location, lowering peak temperature, reducing gradient and bending.

  • Both ends of jaw deflect away from beam. (Note: swelling component of deflection is not corrected - ~ the same as for stop @ 45o.)

  • Max deflection toward beam reduced if the shaft deflection can be minimized

  • Cooling coils embedded in I.D. of jaw.

2006-06-21Coll Eng E Doyle 8/18

Advances since RC1 Baseline

more cooling

solid core

2006-06-21Coll Eng E Doyle 9/18

Evolution of jaw-hub-shaft25mm deep cooling tubes

SS 1hr beam

Transient 10sec @12min beam

RC1 – not a practical support scheme



Next for jaw-hub-shaft:

Alternative materials to reduce shaft deflection

Note reduced shaft end deflection – a positive result if stop is used

2006-06-21Coll Eng E Doyle 10/18

Alternative Shaft MaterialsShaft supported case -Slight Improvement

Deflection is combo of bending & swelling

2006-06-21Coll Eng E Doyle 11/18

Alternative Shaft MaterialsCentral stop-supported case - No Improvement

Note: values in table manually adapted from simulation results based on jaw edge or shaft end supports. Stop located in mid-jaw at 45 degrees from point closest to beam.

2006-06-21Coll Eng E Doyle 12/18

Evaluate jaw-hub-shaft25mm deep cooling tubes

New Baseline

SS 1hr beam



Transient 10sec @12min beam

Note: deflection means deviation from straight (in um). Eff length is length of jaw (in m) deflected

<100 um compared to maximum deflection point.

With stop

con: 2x deflection

pro: 75% reduction of shaft motion

Shaft support only

con: 4x deflection

pro: simpler mechanism, same control architecture as Ph I

2006-06-21Coll Eng E Doyle 13/18

Permanent Deformation

Initial condition: 1 hr beam lifetime heating rate. Transient: 10 seconds heating at 12min beam lifetime rate followed by 50 seconds cooling.


Glidcop AL15

2006-06-21Coll Eng E Doyle 14/18

Permanent Deformation

Permanent bending of jaw after one transient heating cycle. Deflection is concave as seen from beam. Glidcop AL15 effectively prevents plastic deformation.

2006-06-21Coll Eng E Doyle 15/18

Further refinements

  • Optimize hub length, location

  • Hub region solid Cu, two stub shafts of alternative material, butted to hub

  • Shallow cooling tubes (~15mm)

  • Glidcop only where necessary – outer radii

2006-06-21Coll Eng E Doyle 16/18

Xtra Slide

2006-06-21Coll Eng E Doyle 17/18

Evolution of jaw-hub-shaft25mm =>10mm deep cooling tubes

SS 1hr beam

Transient 10sec @12min beam



2006-06-21Coll Eng E Doyle 18/18

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