# Presentation: 128356

##    (Recent) Energy Deposition Simulation in Phase II		     Secondary Collimators			    April 26, 2006

_**US LHC Accelerator Research Program**_

**  **** ****(****Recent) ****Energy Deposition Simulation in Phase II****	****	****     Secondary Collimators****	****	****	****    April 26, 2006**

- L. Keller

_**Two aspects**_:
**Accidental damage.**
**Power in normal LHC operation.**

## SLAC Damage Test - 1971

**Beam diameter**
**    ****~ 2000 μ**

**30 cm**

**Beam entering a few mm from the edge of a 30 cm long ****copper**** block**

_**SLAC Damage Test - 1971**_

**It took about 1.3 sec to melt thru the 30 cm block, but for this relatively large beam, the front two radiation lengths remain intact.**

**The length and depth of this melted region is comparable to the ANSYS **
**	****	****   ****simulation for the LHC accident.**

**500 kW beam **
**     ****0.65 MJ **
**    ****in 1.3 sec**

##                Tevatron Accident – 2003

**               **_**Tevatron Accident – 2003**_
**            **_**Beam Lost on Stainless Steel Collimator**_

**Energy deposition ~0.5 MJ**

**groove is 25 cm long,  1.5 mm deep**

##        LHC  :  A kicker failure can deposit 9 x 1011 protons (8 bunches) on any metallic 

**                   **_**secondary collimator - causing it to melt within a substantial volume. **_

**Missteered beam 9E11protons,**
**    ****1 MJ on secondary Jaw**

**Copper**
**Jaw**

**120 cm**

- _3D ANSYS model, E. Doyle_

**above Cu melting**

**melting**
**25-30 cm**

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

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

**Copper**
**Jaw**

- _3D ANSYS model, E. Doyle_

**Melting zone (grey),**
**radius = 3.3 mm**

**Fracture zone,**
**radius = 7 mm**

**2.5 cm**

## Cross Section at Shower Maximum Showing Copper Boiling     

**2.5 cm**

**Cross Section at Shower Maximum Showing ****Copper**** ****Boiling****     **
**                                **_**in a Mis-steering Accident**_

**Copper**
**Jaw**

- _3D ANSYS model, E. Doyle_

**Boiling zone (grey),**
**radius = 2.2 mm**

##                            Phase II Energy Depostion Simulations

**1.  60 cm carbon primary collimators**
**2.  11 secondary collimators, jaws only**
**       ****a) Phase 1, 120 cm rectangular carbon jaws**
**	****  ****b) Phase 2, 95 cm cylindrical copper jaws**
**4 tungsten absorbers, jaws only**
**24 warm quadrupoles, 2 SC quadrupoles**
**4 warm dipoles**
**6.  All copper beam pipes**

**A.  Before Jan. ‘06 had only simulated energy deposition in the primary collimators **
**     ****and the first secondary collimator where about 80% of the collimated energy is  **
**     ****deposited.**
**B. ****Decided to construct a simple FLUKA model of IR7 to make particular checks**
**    ****of the CERN sophisticated, comprehensive model.  The “simple” model**
**    ****includes**:

## Simple FLUKA Model of IR7

_**Simple FLUKA Model of IR7**_

- dipoles

- dipoles

- quadrupoles

- MQTLH

- 11 rotating-jaw, copper secondary collimators, 4 absorbers

- 3 carbon
-  primary
-  collimators

- beam 1

- beam 2

- 0

- meters

- 200

- 400

## Cross section of 2-jaw rotating-cylinder, secondary collimator, B4L7

- _Cross section of 2-jaw rotating-cylinder, secondary collimator, B4L7_

- X (cm)

- Z (cm)

- 95 cm

- each cylinder 6.8 cm o.r., 4.3 cm i.r.

- beam

- left jaw

- right jaw

- (cut at y = 0)

## Phase 1 RESULTS 

_**Notes**_:
**1. Twelve min. lifetime, power in last seven collimators (>200 m) dominated by direct beam interactions**

**Comparison of Energy Deposition in ****Carbon**** **
**Secondary Collimators for CERN and SLAC  IR7 Models**

_**Phase 1 RESULTS**_

## Phase 2 RESULTS 

_**Notes**_:
**1. Twelve min. lifetime, power in last seven collimators (>200 m) dominated by direct beam interactions**

**Comparison of Energy Deposition in ****Copper**** **
**Secondary Collimators for CERN and SLAC  IR7 Models**

_**Phase 2 RESULTS**_

## Off-energy Protons from Primary Collimator TCPH

**Δ****E/E****b**** = ****-16.4%**

-  Integral = 1.7 x 10-3 / int. beam proton
-  12 min. lifetime => 7 x 108/sec into arc
-  CERN quench level estimate = 7.6 x 106 p/m/sec

**Off-energy Protons from Primary Collimator TCPH**
**                      ****Entering the LHC Arc**

##                 Next Steps for Energy Deposition

_**FLUKA simulations**_**:**
**	****In the Phase II configuration with all 95 cm long copper cylinders, simulate the energy absorbed by the down-beam superconducting dipole magnets – compare with ray-tracing program TURTLE.**
_**ANSYS accident simulations**_**:**
**	**
**      **** ****a)  Use quasi-static (few hundred msec) model to estimate permanent  **
**            ****deformation.**
**      ****b)  Use transient thermal shock analysis to estimate fracture damage.**
**   **
**3.  A ****beam test**** to simulate the LHC accident conditions in a copper, cylindrical collimator is**** highly desirable.**