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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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 3 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 4 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 5 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 6 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 7 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 8 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 9 / 71
Advances since RC1 Baseline
solid core more cooling
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 10 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 11 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 12 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 13 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 14 / 71
Power Absorption in BOTH Copper Jaws of First Secondary Collimator TCSM.A6L7
Lew Keller
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 15 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 16 / 71
Contribution to inefficiency fromeach of several collimators as 1st secondary
is opened from 7 to 8 sigma
Chiara Bracco / CERN
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 17 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 18 / 71
BrazeTest #1 Cooling Tube
Jaw Center Mandrel
~100 mm
~70 mmdia
~100 mm dia
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 19 / 71
Aluminum Mandrel for Coil Winding Test and to test 3-axis CNC Mill before cutting 200mm and
950mm Copper Mandrels
200mm
Cooling Tube aligner
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 20 / 71
Test Bends on Square Hollow Copper Tubing
Preliminary bends just to get some experience
Initial test bend of “Half Turn” wound by hand
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 21 / 71
Attempts to Use Tooling for Bending
Lathe Magnet Coil Winding Instrument
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 22 / 71
Development of Winding Tooling
Vise-Type Roller-Type
Aluminum Mandrel with Coil Wound
Test Winding the 200mm Copper Mandrel
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 23 / 71
Fabrication of Quarter Jaws for 2nd Braze Test
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 24 / 71
Final Wind of 200mm Copper Mandrel
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 25 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 26 / 71
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)
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 27 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 28 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 29 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 30 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 31 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 32 / 71
Steps on Path to a Thermal Test of a Full Length Cooled Jaw
Test Fixture
• Specify details of test stand• Make design drawings• Fabricate
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 33 / 71
Steps on Path to a Thermal Test of a Full Length Cooled Jaw
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 34 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 35 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 36 / 71
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”
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 37 / 71
August 2006 “Plug&Play” Model of Jaw Mounts
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 38 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 39 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 40 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 41 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 42 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 43 / 71
Jaw Mount section view with safety stop
Hard Stop Angular contact bearings
0.5mm thick DiaphragmShaft mounts here
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 44 / 71
Upstream end vertical section
Jaw
Geneva Mechanism
Support Bearings
Worm GearShaft
Water CoolingChannel
U-Joint Axle
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 45 / 71
Upstream end horizontal section
Support to Support 1000mm
Overall length 930mm
Facet length ~905mm
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 46 / 71
Upstream end with actuator and cooling lines
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 47 / 71
Upstream End looking Downstream
Flexible Vanesupports each endof Image Current Plate
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 48 / 71
Image Current Plate
Lundgren
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 49 / 71
Jaw-Hub-Shaft Key Dimensions
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 50 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 51 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 52 / 71
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
Halo on TCPH, 1 hour beam lifetime
Ave. = 13.5 kW/jaw
Ave. = 530 W/shaft
high energy side - photons from TCPH?
Lew Keller
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 53 / 71
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
Halo on TCPH, 1 hour beam lifetime
FWHM ≈ 20º
FWHM ≈ 60º
Lew Keller
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 54 / 71
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)
Halo on TCPH, 1 hour beam lifetime
Ave. = 0.77 W
Ave. = 2.7 W
Lew Keller
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 55 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 56 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 57 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 58 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 59 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 60 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 61 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 62 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 63 / 71
Jaw-hub-shaft – Hollow Mo Shaft
Hub region - centered
Glidcop Jaw
Hollow Mo Shaft
Simple supports at both shaft ends
Doyle
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 64 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 65 / 71
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.
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 66 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 67 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 68 / 71
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
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 69 / 71
Longitudinal and Azimuthal Profiles of Remnant Dose after 30 day exposure
and 1 day cooldown
Mokhov et al
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 70 / 71
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.
LARP Collab. Mtg. - 26 October 2006 Rotatable Collimators - T. MarkiewiczSlide n° 71 / 71
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)