# Presentation: 949644

## LHC Phase II Collimator Status ReportYunhai Cai, Eric Doyle, Josef Frisch, Lew Keller, Tom Markiewicz, Tor RaubenheimerSLAC

- LARP Collaboration Meeting
- Napa, CA
- 20 October 2004

***bnl - fnal- lbnl - slac***

_**US LHC Accelerator Research Program**_

## CERN FLUKA Input File-January 2004

## Phase I Graphite Secondary CollimatorsCERN Analysis Jan.-June 2004

- Track particles around ring for given collimator configuration and lattice
- find collimator where each p interacts inelastically; e.g.
- Run FLUKA jobs forcing interactions in each collimator and look at energy deposited in collimator of interest. Normalize to total particle loss and scale by loss map
- DC particle loss rate: 90kW or 8E10 protons/sec or 1 hour beam lifetime
- Maximum acceptable loss rate: 10 second bursts of 450kW or 4E11 protons/sec or 12 min beam lifetime

## FLUKA Collimators

## Heating of Phase I Graphite Secondary CollimatorsLoss Map#1, 450kW Total Loss Rate, Jaws at 10

- Heating of Phase I Graphite Secondary CollimatorsLoss Map#1, 450kW Total Loss Rate, Jaws at 10

| Total Power | 450 kW |
| --- | --- |
| Power lost in IR7 | 233 kW |
| Power absorbed in beamline elements | 116 kW |

- Engineer Graphite TCS as 7kW device for 90kW DC loss:(7=30/5+margin)
- Handle 30kW for 10 sec as transient

## New SLAC FLUKA / ANSYS Calculations

- Benchmark code implementation by duplicating 6 Feb 2004 CERN results
- Remove the two graphite secondary collimators and look at the energy deposition in two 8cm x 2.5cm x 120cm jaws of the TCSH1 and TCSH2 as a function of material type and material configuration
- Investigate MAXIMUM JAW TEMPERATURE & MAXIMUM COOLING WATER TEMPERATURE in ANSYS given power deposition maps
- 2-d calculations of steady state for 5cm length of jaw at shower max when proton loss rate scaled to 90kW (1 hr. beam lifetime)
- 2-d & 3-d calculations of transient temperature rise, beginning at steady state, for 10 sec excursions to 450 kW (12 min beam lifetime)
- For each geometry:
- Does jaw melt or fracture?
- Does cooling water boil at atmospheric pressure?

## Caveats to SLAC FLUKA Calculations

- Energy deposition results normalized by convention to 4E11p/s = 450 kW total loss (1 hour beam lifetime)
- Use 1.2m long collimators as in CERN study and vary Z
- Shower max in Cu ~20cm total energy absorbed weak function of L
- Each case requires a separate (unavailable) loss map;  We study:
- 100% beam loss on TCPV
- 80% loss on TCPV, 5% TCSH1, 5% TCSH2, 10% outside IR7
- 100% beam loss on TCSH1
- FLUKA input set up for TCP at 5 =±1.0mm and TCS at 10 =±2.0mm
- Used for majority of study, 7 case studied for Cu as a variant
- Design calls for TCP,TCS at 67for phase II running (68.5for phase I)

## Technical Details of SLAC FLUKA Runs

- Start with V. Vlachoudis IR7 model, Rev. 1.5, March 3, 2004
- thanks to Vasilis for helpful discussions
- Removed all regions of earth, concrete, and air
- Raised e+/e- kinetic energy cut from 0.3 MeV to 4 MeV
- after checking Vasilis results
- Raised photon energy cut from 50 KeV to 400 KeV
- after checking Vasilis results
- Recorded energy deposition in all collimator left and right jaws separately.
- Recorded common particle-type fluence entering and exiting collimator jaws
- Start Pencil beam 200 nm from edge of TCPV, and 100 micron from edge of secondary colls

## Heating of 1.2m Cu Secondary Collimators Phase I Carbon design – In-Line with Same Aperture

- 14kW

- 130kW

- 5kW

- 30kW

| TCSH1 (kW) | SLAC | CERN |
| --- | --- | --- |
| Jaws | 111.5 | 116.6 |
| Inox | 7.1 | 7.4 |
| Cu plate | 4.4 | 4.7 |
| Water | 1.1 | 1.1 |
| Total | 124.1 | 129.8 |

- SLAC calculations agrees with CERN’s to 5% for the two cases presented

- Simulation is for 4E11 p/s lost on TCPV

## 25mm Cu Jaws: Relative Contribution from TCPV & from Direct Hits

## 25mm Cu Jaws: “Left” vs. “Right” Jaws

- Dipole sweeps “+” to Left; Photons from TCPV go Right; Jaws at ~45°

## Breakdown of Energy Deposited25mm Cu Jaws in 80:5:5:10 model @ 450kW rate

- Extra 10% power in collimator body

- Jaws ~ equal

## Transverse Power Distribution in 5 cm slice at shower max: 80:5:5:10 model for 4E11 p/s, Upper Right 2.5x8 cm Cu jaws

- Point: How much can we gain by limiting depth or height of high Z part of collimator

## Energy Spectra of Particles Hitting TCSH1

- Energy Spectra of Particles Hitting TCSH1

- Keller: 2004-10-06

- Hadrons-7

- Hadrons-10

- All Particles-10

- All Particles-7

## Spatial Distribution of Particles from TCPV at face of TCSH1 when Jaws at 7 sigma

- Hadrons

- All Particles

## Summary of Shower Content at TCSH1

## Power absorbed in one TCSH1 jaw at 10 when 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- Power absorbed in one TCSH1 jaw at 10 when 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

## Steady State Cooling Estimate for 90kW loss rate

## Effect of reducing TCSH Gap from 10 to 7Sensitivity to Variations in Loss Map90 kW case

- Same caveats as specified in previous slides

## ANSYS Calculations

- What follows is a set of calculations for a secondary collimator which is :
- 	25mm thick COPPER
- 	80 mm high
- 	120 cm long
- Summary results of other materials, gaps, loss distributions follow
- Technical Notes:
- Cv assumed a constant, independent of temperature
- Boundary Condition: Convection Coefficient to infinite reservoir or 20°C water taken as HCH20=11880 W/m2/°C
- This number, indicating efficiency of heat reduction, “reverse engineered” from CERN Phase I design
- Heat flux to water of 1.3W/mm^2 is ballpark critical heat flux for free convection - if you try to exceed this flux the bubbles insulate the surface causing the heat source to increase sharply in temperature.  The heat flux for the onset of boiling is one or two orders of magnitude lower.  For forced convection, these numbers are much higher.

## Transverse Distribution of Power absorbed at shower max in 5cm of 120cm TCSH1 jaw at 10 when 80% (5%) of 90kW of primary beam interacts in TCPV (TCSH1)

- Transverse Distribution of Power absorbed at shower max in 5cm of 120cm TCSH1 jaw at 10 when 80% (5%) of 90kW of primary beam interacts in TCPV (TCSH1)

- 25mm

- 80mm

- Jaw: 25x80mm Solid Cu PTOT=1270W

- Doyle: 2004-09-28

## Steady State Temperature of TCSH1 at shower max when jaw at 10 is in contact with 20°C H2O and 80% (5%) of 90kW of primary beam interacts in TCPV (TCSH1)

- Steady State Temperature of TCSH1 at shower max when jaw at 10 is in contact with 20°C H2O and 80% (5%) of 90kW of primary beam interacts in TCPV (TCSH1)

- 25mm

- 80mm

- Boundary Condition: Convection CoefficientHCH20=11880 W/m2/°C

- CV  Cu taken as constant

- Jaw: 25x80mm Solid Cu PTOT=1270W

- Power Density to H2O
- 0.38 MW/m2(H2O boils at 1 atm @ 1.3E6)

- Doyle: 2004-09-28

## Steady State Temperature of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- Steady State Temperature of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- 25mm

- 80mm

- Boundary Condition: Convection CoefficientHCH20=11880 W/m2/°C

- CV  Cu taken as constant

- Jaw: 25x80mm Solid Cu PTOT=6400W

- Power Density to H2O
- 1.9 MW/m2(H2O boils at 1 atm @ 1.3E6)

- Doyle: 2004-09-28

## Time Dependence of Peak Temperature  of TCSH1 shower max when jaw at 10 is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- Time Dependence of Peak Temperature  of TCSH1 shower max when jaw at 10 is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- Jaw: 25x80mm Solid Cu PTOT=6400W

- Doyle: 2004-09-28

- Beam Side of Jaw

- Water Side of Jaw

- 10 sec

##  Temperature @ 10 sec of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

-  Temperature @ 10 sec of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- 25mm

- 80mm

- Jaw: 25x80mm Solid Cu PTOT=4100W

- Power Density to H2O
- 1.2 MW/m2(H2O boils at 1 atm @ 1.3E6)

- Doyle: 2004-09-28

- Boundary Condition: Convection CoefficientHCH20=11880 W/m2/°C

- CV  Cu taken as constant

##  3D Calc of Temperature @ 10 sec of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

-  3D Calc of Temperature @ 10 sec of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of 450kW of primary beam interacts in TCPV (TCSH1)

- Jaw: 25x80mm Solid Cu

- Power Density to H2O
- 1.2 MW/m2(H2O boils at 1 atm @ 1.3E6)

- Doyle: 2004-09-28

- Boundary Condition: Convection CoefficientHCH20=11880 W/m2/°C

- CV  Cu taken as constant

- Viewed from beam side

##  Temperature of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of primary beam interacts in TCPV (TCSH1)

-  Temperature of TCSH1 at shower max when jaw at 10  is in contact with 20°C H2O and 80% (5%) of primary beam interacts in TCPV (TCSH1)

- Jaw: 25x80mm Solid Cu

- Constant Color Scale

- @ 10 sec 450 kW

- Steady @ 450 kW

- Steady @ 90 kW

## Material Properties

| Z | Specific Heat (J/gmC) | Melting Temperature (C) | E (psi/C) | Ultimate Tensile Strength Limit |  |
| --- | --- | --- | --- | --- | --- |
|  |  |  |  | (psi) | (C) |
| Be | 1.78 | 1278 | 540 | 80000 | 150 |
| Al |  | 660 |  |  | 140 |
| Ti | 0.54 | 1800 | 130 | 100000 | 770 |
| Cu | 0.385 | 1080 | 280 | 50000 | 180 |
| W | 0.134 | 3100 | 220 | 150000 | 680 |

## Materials Study at 90 kW loss rate

- All entries for case of 80% loss on TCPV, 5% on TCSH1, 5% on TCSH2, 10% out of IR7
- All collimators are 80mm “high” and 120cm long
- Primaries at 5 sigma and secondaries at 10 sigma
- Power is that deposited in JAWS only

- All materials considered possible some easier than others

## Materials Study at 450 kW loss rate after 10 sec.

- Same caveats as specified in previous slide

- 25mm thick Cu and W have Temperature above fracture limit and would require pressurized cooling system

## Materials Study at 450 kW loss rate - Steady State

- Same caveats as specified in previous slides

- Although NOT a strict requirement as specification calls for beam dump after 10 sec:25mm thick Ti and 5/20mm Cu/Be have Temperature above fracture limit; Ti would require pressurized cooling system

## Effect of Doing 2D versus 3D ANSYS calculations90 kW case

- Not a big effect, even for Cu

## Conclusions

- At our current level of understanding
- Thin Cu,	10 kW
- Al,	  7 kW
- Be,	  1 kW
- Collimators seem feasible.  Total power needs to be scaled by
- +10%	Non-Jaw part of collimator
- +25%	Gap at 7 sigma
- Small%	Changes in loss map
- -~25%	If length reduced
- +25%	Margin + more sophisticated calculations
- Al and thin Cu not too dissimilar from CERN Phase I Carbon (6kW +1kW)
- Be seems “easy”-need to understand limitations
- Can we design 10kW in rotating geometry? Can we meet space constraints?
- Will material maintain mechanical tolerances when loss rate goes to 450 kW?