larp rotatable collimators for lhc phase ii collimation 26 october 2006 larp collaboration meeting...

LARP Rotatable Collimators for LHC Phase II Collimation

26 October 2006LARP Collaboration Meeting – Port Jefferson, NY

Tom Markiewicz/SLACRepresenting Eric Doyle, Lew Keller & Steve Lundgren

BNL - FNAL- LBNL - SLAC

US LHC Accelerator Research Program

LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 2 / 71

Collimator Design as of April 2006

beam

beam

•136mm diameter x 950 mm long copper jaws (750 mm effective length + 2 x 100mm tapers)

•Vacuum tank, jaw support mechanism and support base derived from CERN Phase I


EXTERNAL COIL PERMITS 1 REV OF JAW

CERN PHASE I JAW POSITIONING MECHANISM – USE IF POSSIBLE

25mm thick annular (hollow core) copper jaw backed by continuous helical cooling tube

Collimator Design as of April 2006

NLC Jaw Ratchet Mechanism assumed

Sheet Metal formed RF transition


Stop prevents thermal bowing of jaws from intruding on minimum gap. Deal with:

•Residual swelling into beam•External vertical actuator and bellows that also has +/- 5mm transverse float•Mid-jaw recess•Forces possibly unbalanced front vs. back

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

•Thermal motion while minimizing gravity-deflection

•Axial expansion

Adjustable central aperture-defining stop and leaf spring support required to prevent jaws

from deforming 1200um into beam


RF Contact Scheme Blessed by CERN Impedance Police

Rigid round-square transition

Spring loaded fingers ground two jaws through range of motion

Jaw support & gap adjustment borrowed from CERN


Collimator TCSM.A6L7 Cooling scheme Helical Axial (36o)

# channels 1 2 Diam (m) .008 .006 Velocity (m/s) 3 3

Cooling

Total flow (l/min) 9 10 SS Power (kW) 11.7 Beam heat Trans Power (kW) 58.5

Jaw peak 86.5 91.5 Cooling chan. peak 68.3 69.7

SS

Water out 36.0 36.1 Jaw peak 231 223 Cooling chan. peak 154 130

Temp (C )

Trans

Water out 43.6 47 SS 394 107 Deflection (um) 4 Trans 1216 778 SS 43 75 Eff. length (cm) 5 Trans 24 31

Exceeds 200 Max Cu temp

Possible boiling

Exceeds 42 max water return temp

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

Exceeds spec, or other possible problem as noted

Baseline Jaw Performance

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


Technical Review of Baseline 12-2005

• Do not ‘cut metal’ until jaw support, stop and rotation scheme developed• Increase engineering effort

Response– Full time engineer (Steve Lundgren) & full time designer hired April 2006– Doyle, Keller, & Markiewicz continue on part time basis

Result– New jaw design developed which eliminates central stop & flexible

springs– New concept for winding the cooling coil which eliminates the 4 loops per

end and permits longer jaw and better RF-compliant jaw support– New scheme for rotating after beam abort damages surface– Test pieces constructed & examined

BUT…– Still do not have tested full length jaw or complete RC1 prototype


Progress since April 2006 Meeting

Design & Calculation– Improved and much more complete design– ANSYS calculations to simulate performance of new design– ANSYS calculations to start to look at permanent deformation in

case of accidental beam abort– FLUKA model improvements to understand heating/cooling in

more elements (shaft, bearings, …) of the collimator

Fabrication– Fab, brazing & dissection of short (15cm) section of jaw:

• cooling coil to mandrel and of coil/mandrel assembly to jaw

– Fabrication of short aluminum mandrel to practice coil winding & development of coil winding tooling

– Fabrication of 2nd short (20cm) copper mandrel and jaw pieces• test braze techniques required for longer jaw pieces


Advances since RC1 Baseline

solid core more cooling


New Idea to Eliminate Central Stop Jaw-Hub-Shaft

1. Hub located, in Z, near peak temperature location, which lowers peak temperature, reducing gradient and bending.

2. Max deflection toward beam reduced if the shaft deflection can be minimized

3. Both ends of jaw deflect away from beam. (Note: swelling component of deflection is not corrected.)

4. Cooling coils embedded in I.D. of outer cylinder.

shaft jawhub


shaft end d deflection eff lengthdeflection reference jaw edge shaft stop stop n/a n/abaseline (25mm) 394 426 36 390 394 0.43refined baseline (25mm) - 238 24 214 202 0.63refined jaw-hub-shaft - 84 - - 197 0.74

baseline (25mm) 1216 1260 97 1163 1216 0.24refined baseline (25mm) - 853 76 777 913 0.31refined jaw-hub-shaft - 236 - - 781 0.39

jaw max d toward beam

Evaluate jaw-hub-shaft for 750mm jaws22.5mm deep cooling tubes with solid copper shaft

Transient 10sec @12min beam

SS 1hr beam

Notes:1. Deflection means deviation from straight (um).2. Eff length is length of jaw (m) deflected <100 um compared to maximum deflection point.3. Deflection is combination of swelling and shaft bending4. Shaft static deflection due to gravity = 68um5. 7 min allowable aperture achieved by setting jaws of first collimator at 8.5 .

New Baseline


First Concept to Eliminate 4-Loop Coils at Ends to allow increased jaw length and realistic jaw holder

that is “plug&play” replacement for Phase I jaw

Restrain each tube on centerline of bearing

200mm

136mm dia

Annealed pre-bent cooling coil and dead recon winding to put U-Bend

at exact midpoint of mandrel

Model of Coil Winding Test piece 200mm

long x 86mm diameter

Lundren


Summary of New Baseline Configurationon 1 Sept 2006

Jaw consists of a tubular jaw with embedded cooling tubes, a concentric inner shaft joined by a hub located at mid-jaw

Major thermal jaw deformation away from beamNo centrally located aperture-defining stopNo spring-mounted jaw end supportsJaw is a 950mm long faceted, 20 sided polygon of GlidcopShorter end taper: 15mm L at 15o (effective length 920mm)Cooling tube is square 10mm Cu w/ 7mm square aperture at depth = 24.5 mmJaw is supported in holder

jaw rotate-able within holderjaw/holder is plug-in replacement for Phase I jaw

nominal aperture setting as low as 8.5 Results in minimum aperture > 7s in transient 12 min beam lifetime event

(interactions with first carbon primary TCPV)absorbed power relatively insensitive to aperture: for 950mm long jaw

p=12.7kW (7), p=12.4kW (8.23)Auto-retraction not available for some jaw orientationsJaw rotation by means of worm gear/ratchet mechanism


Power Absorption in BOTH Copper Jaws of First Secondary Collimator TCSM.A6L7

Lew Keller


Collimator Inefficiency when the TCSM.A6L7 collimator only is opened from 7 to 8 or 8.5 sigma for each beam

and for each primary collimator orientation

Halo Length [mm]

Half gap[]

Imax

[%]

η @ 10σ

Lwb.hor.b1 75 7 65.7918.96 9.3610-6

Lwb.hor.b1 75 8 79.0525.26 1.2410-5

Lwb.vert.b1 75 7 62.5017.82 1.9410-5

Lwb.vert.b1 75 8 35.096.19 2.0110-5

Lwb.hor.b2 75 7 45.6610.50 1.6110-6

Lwb.hor.b2 75 8 78.7423.90 1.8310-6

Lwb.vert.b2 75 7 81.6321.81 5.0710-6

Lwb.vert.b2 75 8 67.1115.26 5.4210-6

Lwb.skew.b1 75 7 86.5843.49 5.2510-6

Lwb.skew.b1 75 8 57.9723.69 7.5410-6

Lwb.skew.b1 95 7 79.5137.25 8.5910-6

Lwb.skew.b1 95 8.5 69.4431.01 8.1410-6

Chiara Bracco / CERN


Contribution to inefficiency fromeach of several collimators as 1st secondary

is opened from 7 to 8 sigma

Chiara Bracco / CERN


Steps on Path to a Thermal Test of a Full Length Cooled Jaw:

#1 Test Pieces

Braze Test #1 Wind any available 10mm x 10mm tubing on convenient sized and available

copper stock for mandrel and jaws Develop and document braze procedures Section for braze inspection, document results

Coil winding Procedure and hardware Develop procedure and tooling to wind available tubing on short 200mm length

Aluminum mandrel Test 3-axis CNC milling procedure required to machine U-bend in cooling pattern

Braze Test #2 Machine short 200mm copper mandrel Wind annealed available tubing on copper mandrel and stake in place to hold– Braze tubing to mandrel– Machine OD and add groove to hold braze wire Machine 4 quarter 200mm jaws– Braze with wire & foil– Section for braze inspection, document results


BrazeTest #1 Cooling Tube

Jaw Center Mandrel

~100 mm

~70 mmdia

~100 mm dia


Aluminum Mandrel for Coil Winding Test and to test 3-axis CNC Mill before cutting 200mm and

950mm Copper Mandrels

200mm

Cooling Tube aligner


Test Bends on Square Hollow Copper Tubing

Preliminary bends just to get some experience

Initial test bend of “Half Turn” wound by hand


Attempts to Use Tooling for Bending

Lathe Magnet Coil Winding Instrument


Development of Winding Tooling

Vise-Type Roller-Type

Aluminum Mandrel with Coil Wound

Test Winding the 200mm Copper Mandrel


Fabrication of Quarter Jaws for 2nd Braze Test


Final Wind of 200mm Copper Mandrel


Update Cooling Coil Wind Concept Based on 200mm Wind Tests

Shifting the u-bend from the midpoint of the Mandrel to near the downstream end gives the following benefits:– The groove in the u-bend area can be eliminated reducing the

need for precise initial bend locations.– The u-bend can be made larger in diameter to reduce the internal

distortions in the cooling channel and improve water flow.– The groove and relief can be machined on a lathe rather than on a

CNC milling machine reducing the overall cost.

Result– Mandrel has a groove the appropriate width and depth for the

conductor and goes 42.5 turns in the same direction. – Mandrel has one 80mm wide “groove” at downstream end to

accommodate the u-bend and a enough conductor wrap around about 1 turn (provides a generous allowance for errors in machining and bending locations).

– U-bend can be 20 to 30mm diameter not only 10mmMarkiewicz


Model showing Coil wound on Mandrel with U-Bend at downstream end

Note: Braze Test #3 will probably need to be

added to step #1

1. Fab 2nd 200mm mandrel on lathe

2. Test wind coil with downstream U-Bend

3. Under discussion: use 8 quarter round jaw sections to make sure butt brazes pose no problem (as promised)


Steps on Path to a Thermal Test of a Full Length Cooled Jaw

Manufacture Full Length Jaw

– Machine 930mm mandrel with new winding pattern• Mandrel had been released for fabrication with requested due date 10/27/06 • Drawings for full length mandrel modified to put loop at end and resubmitted

– Acquire CERN-compliant (Nickel alloyed) copper tubing from Finland– Build tooling using roller concept for full length jaw– Shape & anneal tubing– Wind tubing to mandrel– Machine OD and add groove to hold braze wire– Machine (wire EDM) at least 8 full half length (465mm) quarter jaws from

copper (NB: Final jaws will be Glidcop)• Released to SLAC shops for fabrication on 1 OCT 2006,

– Original promise date 11/08/06– Cost estimates are very high and we are examining issues involved in

designing shorter pieces fabricated by other means– Braze jaws to mandrel assembly– Design & order shaft in MOLYBDENUM

• Order has been placed with vendor: promise date 11/28/06– Braze shaft to jaw assembly– Machine 20 facets on jaw face– Machine features required to interface resistive heater packages


ANSYS Model of Jaw-hub-shaft with hollow Mo shaft

Hub region - centered

Glidcop Jaw

Hollow Mo Shaft

Simple supports at both shaft ends

Deflection

Temp


Comparison of Hollow Mo shaft and Solid Copper Shaft to same FLUKA secondaries: Improved deflections

Solid Cu, 75cm tapered jaw, asymmetric hub

Tubular Moly, 95 cm straight jaw, symmetric hub

Steady State=1 hour

= 12 min for 10 sec

Steady State=1 hour

= 12 min for 10 sec

Gravity sag 200 um 67.5 um

Power absorbed 11.7 kW 58.5 kW 12.9 kW 64.5 kW

Peak Temp. 66.3 °C 197 °C 66 °C 198 °C

Midjaw x 100 um 339 um 83.6 um 236 um

Effective Length 51 cm 25 cm 74 cm 39 cm

Sagitta 221 um 881 um 197 um 781 um


Molybdenum Shaft Details

Relief on I.D. is for roller bearing

Slots for tubing extend past bearing and are 180 deg offset

Relief on O.D is for stiffening sleeve and worm gear mounting

1mm raised shoulder (Hub) at center


Single Jaw Thermal Test Hardware

Jaw Sections

~450 mm long Jaw sections are manufactured as quarter cylinders for fabrication accuracy and ease of braze assembly

Only 4 or 5 flats are planned for the test and for measurement purposes



Test Fixture

• Specify details of test stand• Make design drawings• Fabricate



Test Lab Preparation

Clean space with gantry access Basic equipment: Granite table, racks, hand

tools Power supplies to drive heaters Chiller & plumbed (?) LCW to cool jaw– 480V wiring for heater power supplies

• required engineering review, safety review, and multiple bids (?!)

• 23 Nov 2006 promise date

– Acquire Heaters• 5kW resistive heaters available on short notice

from OMEGA PC & Labview

Rudimentary software tests only National Instruments DAQ with ADCs

• Data Acquisition and Control Module• 32-Channel Isothermal Terminal Block• 32-Channel Amplifier

– Thermocouples (?)– Capacitive Sensors (?)– Vacuum or Nitrogen (?)– Safety Authorization (!!!)

Collimator Assembly & Test Area in SLAC Bldg.33


Equipping of Clean Collimator Test Area

Granite surface plate Adjacent 16.5 kW Chiller

Heater Power Supplies staged for installation in rack

Instrumentation rack and computer workstation


Beginnings of System Schematic for Single Jaw Thermal Test Hardware

Test Lab Setup Block Diagram

PC with LabViewSoftware

Heater #1 Controller

Heater #2 Controller

Capacitec Signal Amplifier

DAC & Signal ProcessorJaw thermocouples

Jaw deflectionsensors

Jaw Heater #1

Jaw Heater #2

Over Temperature Control

Jaw Internal Cooling

Line

Chiller

LCW Water (Supply)

LCW Water (Return)

fuse

fuse

fuse

fuse

Bldg Power

Bldg Power

100 Amp Tap


Steps on Path to RC1

• Successful thermal performance of first full length jaw• Complete design of RC1 support, rotation & RF features

– Layouts, calculations and models of two Jaw mounting methods as well as a rotation scheme have been explored….

– Detail drawings of the preferred Jaw mounting method and rotation mechanism are in work.

– A working model is planned to verify the rotation scheme with respect to Jaw face position accuracy.

• Acquisition, Fabrication & Assembly cycle of the support, rotation & pieces• Fit-up and initial tests on 1st full length jaw• Complete fabrication of second jaw (Glidcop?, Moly??) with full support

assembly• Remodeling of CERN parts for interface to US parts

– Models and assemblies of the various Collimator Mounting Stands are complete

– An enlarged vacuum tank has been modeled and some CERN support stand modifications have been identified

– No fabrication drawings have been done as yet• Acquisition of Phase I support & mover assemblies

– Given delivery difficulties of CERN Phase I this has dropped off CERCA/AREAV and CERN event horizon despite promise 1 May 2006 that SLAC quote was “in the mail”


August 2006 “Plug&Play” Model of Jaw Mounts

Lundgren


August 2006 Jaw mounting details

Draws on features from CERN Phase 1 Collimator

CERN Contact RF Assy can be

used

Modified CERN Pivot Tensioning Plate

Positioning and Guiding Plates are

similar to CERN Design

Top and Bottom RF springs (not shown)are identicalTo CERN part

Press here to activate 2 leaf springs producing linear motion to rotate a worm/ratchet shaft

Note 20-sided faceted face:

Lundgren


August 2006 Ratchet, Worm and Worm Gear

Shaft and Jaw mount details not shown for clarity

100 Tooth Worm Gear(mounts to shaft)Single turn

Worm20 Tooth ratchet

Bearing 2X

Lundgren


October 2006 Design Model Replaces Worm Gear with “Geneva Mechanism” for Jaw

Rotation and Replaces Needle Bearings with Universal Joint and Angular Contact Bearings and Incorporates Cooling for Support Pieces

– A Geneva Mechanism is the key factor in indexing the Jaw.

• Prevents possible over-run of ratchet.

• Eliminates step count as determining factor in exact facet positioning.

– Universal joints connect Jaw ends to angular contact bearing sets.

• The stainless steel diaphragm “u-joint” meets required torque, Jaw/shaft sag and end-to-end “slew” offset spec of =/-1.5 mm.

• ANSYS calculations performed to verify diaphragm thickness & dia.

• Built-in hard stops prevent damage from potential high accelerations during handling and transport.

• Maximum stress on diaphragm is 1/2 yield strength of the stainless steel.

Lundgren


Universal Joint required motions

– Thermal Expansion of molybdenum Shaft of 0.290mm (transient) causes each diaphragm to distort by 0.145mm.

– Shaft sag causes an in plane rotation of the Shaft ends of 0.00025 radians causing an equal distortion of the diaphragm.

– Transverse displacement one of the ends of the Shaft relative to the other by +/- 1.5mm causes an angular distortion of 0.0015 radians in the diaphragm.

– Worst case is for a Vertical Collimator with maximum “slew” of 0.0015 radians added to the sag component of 0.00025 radians

for a total of 0.00175 radians of bending of the diaphragm.

Lundgren


Jaw Mount with Geneva Mechanism

0.5mm thick diaphragm

100 Tooth Worm Gear

Geneva Driver Wheel (on ratchet shaft)

Geneva Driven Wheel(on Worm shaft)

Lundgren


Jaw Mount section view with safety stop

Hard Stop Angular contact bearings

0.5mm thick DiaphragmShaft mounts here

Lundgren


Upstream end vertical section

Jaw

Geneva Mechanism

Support Bearings

Worm GearShaft

Water CoolingChannel

U-Joint Axle

Lundgren


Upstream end horizontal section

Support to Support 1000mm

Overall length 930mm

Facet length ~905mm

Lundgren


Upstream end with actuator and cooling lines

Lundgren


Upstream End looking Downstream

Flexible Vanesupports each endof Image Current Plate

Lundgren


Image Current Plate

Lundgren


Jaw-Hub-Shaft Key Dimensions


ceramic bearing

Molybdenum shaft: R = 2.2 -3.2 cm

bearing axle

Copper cylinder + cooling loops: R = 3.3 – 6.8 CM, Z = 95 CM

beam axis

Extension of SLAC Simple FLUKA Model to include cylinder Copper jaws, Hollow Moly

Shaft, Ceramic bearings, Shaft axel, and support blocks for TCSM-A6L7

Alum.Alum.

image current block

Lew Keller


Results for TCSM-A6L7 at 7 Sigma

Total power deposition

Copper jaws Molybdenum shaft Axial Al struts Front Al image-current blockRear Al image-current blockFront ceramic bearing Rear ceramic bearingFront steel bearing spindleRear steel bearing spindle

13,500 W 530 W 70 W 35 W 90 W 0.1 W 0.8 W 0.5 W 2.7 W

Halo on TCPH, 1 hour beam lifetime

Lew Keller


Copper jaws, 95 cm long, 3.3 - 6.8 cm radius

0

500

1000

1500

2000

2500

0 20 40 60 80 100

Z (cm)

Po

wer/

5 c

m

upper right jaw, 13.7 kW

lower left jaw, 13.3 kW

Molybdenum shaft, 95 cm long, 2.2 - 3.2 cm radius

0

10

20

30

40

0 20 40 60 80 100

Z (cm)

Po

wer

/5 c

m

upper right shaft, 513 W

lower left shaft, 547 W

Axial Power Distribution in TCSM-A6L7 Copper Jaw and Molybdenum Shaft


Ave. = 13.5 kW/jaw

Ave. = 530 W/shaft

high energy side - photons from TCPH?

Lew Keller


Molybdenum shaft, 95 cm long, 2.2 - 3.2 cm radius

0102030405060

0 40 80 120 160 200 240 280 320 360

Phi (deg)

Po

wer/

10 d

eg

upper right, 513 W

lower left, 547 W

Copper jaws, 95 cm long, 3.3 - 6.8 cm radius

0

1000

2000

3000

4000

5000

0 40 80 120 160 200 240 280 320 360

Phi (deg)

Po

wer/

10 d

eg

upper right, 13.7 kW

lower left, 13.3 kW

Azimuthal Power Distribution in TCSM-A6L7 Copper Jaw and Molybdenum Shaft


FWHM ≈ 20º

FWHM ≈ 60º

Lew Keller


Steel bearing axle, 2.5 cm long, 0 - 1.5 cm radius, back end

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 40 80 120 160 200 240 280 320 360

Phi (deg)

Po

wer

/10

deg

upper right, 2.7 W

lower left, 2.8 W

Ceramic bearings, 1.5 cm long, 1.5 - 2.2 cm radius, back end

0.00

0.01

0.02

0.03

0.04

0 40 80 120 160 200 240 280 320 360

Phi (deg)

Po

wer

/10

deg

upper right, 0.75 W

lower left, 0.79 W

Azimuthal Power Distribution in TCSM-A6L7 Ceramic Bearing and Axle (back end)


Ave. = 0.77 W

Ave. = 2.7 W

Lew Keller


Shaft heating SS & Transient

Modeling assumptions:

-Power concentrated in 120o of circumference

-Power constant in length

-No heat transfer at shaft ends

-No radiative heat transfer

Steady State result: T = 232C, ux = 96 um

Transient result: T = 244C, ux = 337 um

Molybdenum shafts

0

10

20

30

40

0 20 40 60 80 100

Z (cm)

Po

wer

/5 c

m

upper right shaft, 501 W

lower left shaft, 542 W

28.5 avg

Molybdenum shaft

0

10

20

30

40

50

60

0 100 200 300 400

Phi (deg)

Po

we

r/1

0 d

eg

upper right, 501 W

lower left, 542 W

Eric Doyle


Jaw mount – tie rod heating hand calculations

FLUKA => 100 W per rod, steady stateAssume uniform heating along length

Assume conduction only to end mounts at 20C, no radiative heat transfer

Peak temperature = 200C, L =~ 3mm

=> must cool tie rods

Tie rod

Eric Doyle


Hand Calculations for Heating/Cooling of Bearings in Steady State Beam Loss

Steel bearings – ball temperature calcs

Power density (FLUKA): 40.8e3 W/m^3Radiation-only heat loss from ballT=113C (upbeam) , 285C (downbeam)

Si3N4 bearings – ball temperature calcs

Power density (FLUKA): 6.5e3 W/m^3Radiation-only heat loss from ballT=26C (upbeam) , 62C (downbeam)

=> use ceramic bearings

Eric Doyle


Status & Plans for Studies of Phase II Collimators in the case of a 1 MJ Beam Abort Accident

2000um 500 kW 20 GeV e- beam hitting a 30cm Cu block a few mm from edge for 1.3 sec (0.65 MJ)

FNAL Collimator with .5 MJ

Trying to negotiate 2007 beam test at CERN to study extent of damage


Cross Section at Shower Maximum Showing Copper Melting and Possible Fracture Regions in a Mis-steering Accident

CopperJaw

Melting zone (grey),radius = 3.3 mm

Fracture zone, (200 C)radius = 7 mm

2.5 cm

~1MJ

Keller, Doyle


Alum.Alum.

image current block

Accident Energy Deposition in Down-beam Aluminum Image-Current Block should NOT cause damage

Total Edep ≈ 3 kJΔTmax < 100 °Cin the image current block

Two accident conditions:

1. All bunches hit the front of the collimator: 7 - 10 σx

2. Grazing angle along collimator edge: at 50 µrad grazing angleand 200µ σx, only about 15% of the beam hits along the edge

1 MJ of bunches hitting edge, 7-10

Lew Keller


Quasi-steady state ANSYS analysis to answer question of whether PLASTIC DEFORMATION of ENTIRE JAW

will happen after a BEAM ABORT ACCIDENT

PRELIMINARY RESULT:– Discrepancy between temperature results using different (coarse vs.

fine mesh) models– 0.23 MJ dumped in 200 ns into coarse ANSYS model– Molten material removed and model allowed to cool– Result:

• plastic deformation on order of 100 um after cooling, sagitta ~60um– Jaw ends deflect toward beam

• Jaw surfaces at 90 to beam impact useable, flat within 5 um

CAUTION: WORK VERY NEW

Doyle

beam side

far side

120 um

-80 um

ux

60 um


Modeling Details of Quasi-steady state ANSYS analysis to answer question of whether PLASTIC DEFORMATION of ENTIRE JAW will

happen after a BEAM ABORT ACCIDENT

Relatively coarse ANSYS model used – same model as steady state & transient simulationsLength 95cm, ends not taperedElements @ O.D.: 2.5 x 8 x 50 (mm r,,z)

Temperature dependent stress-strain (bilinear isotropic hardening)Other properties independent of temperature

Steady state energy deposition profile scaled to equal power of high resolution FLUKA accident data0.23 MJ in 200 nsAxial distribution very similarr, distribution more diffuse

Quasi-steady state analysis of stressesAfter 200 ns energy deposit, model allowed to cool for 60 sec to ~ steady temperature

Doyle


Jaw-hub-shaft – Hollow Mo Shaft

Hub region - centered

Glidcop Jaw

Hollow Mo Shaft

Simple supports at both shaft ends

Doyle


High Resolution and Low Resolution Models

High Res Accident model, elements .2 x .16 x 50mm (r,,z), molten zone in gray: 3 x 5.2 mm (r,) at shower max.

Permanent deformation simulation: Low resolution accident model, elements 8 x 2.5 x 50 mm (r,,z). Energy density is well represented in z, coarsely in r & .

5mmmelt

8 mm

z-variation of power input at shower max: fine (accident case) & coarse (ss) x scale-factor

0.00E+00

5.00E+10

1.00E+11

1.50E+11

2.00E+11

1 3 5 7 9 11 13 15

z-station

po

wer

(W

)

fine(accident)

coarse*(s.f.)

Similarity in z of coarse model (scaled x e8) and fine model.

Doyle


High Resolution and Low Resolution Models – Inconsistent Results

5mmmelt

8 mm

Tmax = 57 e3

Tmax = 550

1 5 9

13 17 21 25 29 33 37 41

S1

S100.00E+00

2.00E+02

4.00E+02

6.00E+02

8.00E+02

1.00E+03

1.20E+03

1.40E+03

1.60E+03

Each coarse element corresponds to 40 x 16 fine elements. Factor of 13 difference attributable to element size, peak temperature dilution in large elements. This leaves a factor of 8 apparent inconsistency. Hand calc energy in single bin confirms 550 result. Next: re-check fine model result.


Permanent Deformation, ux, uy

ux

uy

•In plane deformation, ux ~ 100 um

•Normal deformation (ignoring expansion due to residual axial thermal gradient), uy < 10um

•Therefore, after hit, rotate jaw 90o

uy

50 um

-50 um

27 um thermal expansion

bottom

top<10 um

beam side

far side

120 um

-80 um

ux

60 um

T = 12o C

Doyle


Energy Deposition in WATER in case of Accidental Beam Abort

FLUKA model: 75 cm long cylindrical model • cylinder of copper (or carbon) with i.r. = 4.3 cm. o.r. = 6.8 cm. • cylinder of water with i.r. = 3.6 cm, o. r. = 4.3 cm• inner cylinder of copper (or carbon) with i.r. = 0, o.r. = 3.6 cm For copper the maximum E_dep (at Z = 50 cm) is 0.028 GeV/proton/cm3, which gives about a

1 °C instantaneous temp. rise for 9E11 protons, in that region UsingBulk modulus = 2.07e3 MPaCoeff of vol expansion = 206e-6/K Pressure rise for a sudden 1K temp rise is P = 2.07e3 x 206e-6 x 1 = 426e-3 MPa = 61.8 psi This is about 4 bar while CERN claims 40bar. How can we check this result? Even at 40 bar (only 600 psi) it doesn't seem catastrophic. It's only about 10% of the yield

strength of soft copper. And the copper will get hotter and want to expand even more, which would quickly relieve the pressure. Probably most of the expansion energy would be dissipated in the water up and down stream from the hot spot.

Doyle, Keller


Induced Activation of Secondary Phase II Collimators

Issue Raised by DOE/LARPAC Reviews

Contact Dose Rate for Exposures at 4E9 p/s loss rate

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

Cooling Time (sec)

mS

v/h

r 30d

100d

1yr

20yr

1min 1hr 1d 1wk 1mo 1yr

Exposure

( t~1 day )

15 mSv/yr = max dose for rad worker at CERN

Work in progress by Mokhov et al


Longitudinal and Azimuthal Profiles of Remnant Dose after 30 day exposure

and 1 day cooldown

Mokhov et al


Inter-Lab Collaboration

Good will & cooperation unfortunately limited only by busy work loads– Monthly video meetings – Many technical exchanges via email– Participation in Fall 2006 Phase I testing– Participation in upcoming CERN Phase II brainstorming meeting

Areas where CERN help would be extremely valuable to SLAC project– As vendor of collimator jaw assembly is having problems delivering

Phase I jaw mechanisms to CERN we have lost our minimal contact. Intervention with vendor or use of CERN prototype hardware would be most appreciated.

– Similar comment regarding spare support and mechanism to set gross x, y, u jaw angles

– Plans for damage beam tests before final delivery date would remove large and growing risks of damage sufficient to negate entire “rotatable” concept. 2007 tests on first jaws highly desirable from SLAC perspective.


Phase II Task Summary

There has been fantastic progress in design and good but slow progress on the necessary small scale projects to finalize procedures.

Time estimates for thermal test of first jaw and construction of first 2 jaw prototype (RC1) are expanding. In June DOE was told

“Expect thermal tests and completely tested RC1 device by end of FY06 and mid-FY07, respectively”

We are increasing efforts to find another full time physicist

We are starting to change design when it can help schedule and are starting to plan parallel tests for separate technical issues (spend $ to save time).

Better project management needed.

We hope slippage hopefully consistent with CERN’s newest schedule (admittedly poor excuse)

larp rotatable collimators for lhc phase ii collimation 26 october 2006 larp collaboration meeting...

Documents

larp rotatable collimators

length jaw

jaw support mechanism

new jaw design

cern slide

markiewiczslide n

beam slide

jaw end motion