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A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
1TS department – Mechanical and Material Engineering GroupCERN, Geneva
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Limits of Phase I Collimators
1. Resistive ImpedanceAccording to RF simulations, Phase I Collimator Impedancewould limit LHC beam intensity to ~40% of its nominal value!
2. Cleaning efficiencyCleaning efficiency (i.e. ratio escaping protons / impacting protons) should be better than 99.9% to limit risks of quench at SuperConducting triplets
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Design GuidelinesTo overcome this limit, new secondary collimators with an improved jaw material /design should complement the existing system (Phase II)
To achieve the new goal, we need a magic material having:1. High electrical conductivity to improve RF stability2. High thermo-mechanical stability and robustness, i.e.:
a. Low Coefficient of Thermal Expansion b. High Yield Strengthc. Low Young’s Modulusd. High Thermal Conductivitye. High Specific Heat
3. High density (high Z) to improve collimation efficiency (i.e. intercepted and stop a higher number of particles), possibly depending on final jaw length …
4. Strong resistance to particle radiation …
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Electrical conductivity [1/Electrical conductivity [1/ΩΩm] m] Directly related to resistive impedance
SteadySteady--state geometrical stability parameter [W/m]state geometrical stability parameter [W/m]Indicates power required to induce a given deflection
Transient Thermal Shock parameter [J/kg]Transient Thermal Shock parameter [J/kg]Gives an indication of the highest acceptable deposited energy per unit mass during a beam impact before damage occurs
Mass density [kg/mMass density [kg/m33]]Related to cleaning efficiency
Phase II Collimator Materials
γ
ραk
Relevant figures of merit:
ανσ
Ecpy )1( −
ρ
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Collimator Materials
My strong Assumption:Max Integrated
Energy on a cross-section
independent of material (assuming infinite jaw length)
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Collimator MaterialsHow Geometrical Stability Parameter is obtained:
αραρ
ρ
ααρ
kek
ey
keBT
BTydAyT
Iy
B
BA
÷⇒÷′′
÷Δ
Δ=Δ=′′= ∫
max
)(1
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Collimator MaterialsHow Thermal Shock Parameter is obtained:
[ ] [ ]
ανσ
νασ
ρ
νασ
Ec
ec
eE
ckgJe
cmJUT
TE
p
p
pp
)1()1(
//
1
maxmax
maxmax
max3
maxmax
maxmax
−=⇒
−=
⇒==Δ
−Δ
=
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Collimator MaterialsGeometrical stability parameter (2) vs. Transient Shock Parameter
Silicon Carbide
SiC Accuratus
SiC Kyocera
Molybdenum
Tungsten
Silicon Nitride
Inermet 170
CuCrZr
Beryllium
Aluminum (6201-T81)
Graphite (R4550)
Diamond-based Cu (80% C)
Diamond-based Al (80% C) Carbon/Carbon (AC150 K)
Glidcop AL-15
Diamond-based Ag (Plansee)
Diamond-based Ag (80% C)
AlBeMet
Aluminum Nitride
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.00E+04 1.00E+05 1.00E+06 1.00E+07
Transient Shock Parameter [J/kg]
Geo
met
rical
Sta
bilit
y Pa
ram
eter
[W
m2/
kg]
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Collimator MaterialsGeometrical stability parameter vs. Electrical Conductivity
Inermet 170
Tungsten
CuCrZr
Beryllium
Aluminum (6201-T81)
Graphite (R4550)
Diamond-based Cu (80% C)Diamond-based Al (80% C)
Carbon/Carbon (AC150 K)
Glidcop AL-15
OFE- Copper
Diamond-based Ag (Plansee)
Diamond-based Ag (80% C)
AlBeMet
Molybdenum
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08
Electrical Conductvity [S/m]
Geo
met
rical
Sta
bilit
y Pa
ram
eter
[W
/m]
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II Collimator MaterialsMass density [kg/m3]
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Carbon/C
arbon (A
C150K
)
Graphite
(R45
50)
Glidco
p AL-15
OFE-Copper
CuCrZr *
Berylliu
m
Aluminum (620
1-T81
)
Diamond-bas
ed C
u (80%
C)
Diamond-bas
ed A
l (80%
C)
Diamond-bas
ed A
g (Plan
see)
Diamond-bas
ed A
g (80%
) **
AlBeM
et
Aluminum Nitr
ide
Silicon C
arbide
SiC K
yoce
raSiC
Acc
uratus
Tungsten
Molybden
umInerm
et 17
0Silic
on Nitr
ide
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Candidate liquid metals
GaGa, In and , In and SnSn havehaverelatively low melting temperature (<250 relatively low melting temperature (<250 °°C),C),low low PvapPvap at Tm (< 10eat Tm (< 10e--10 10 torrtorr) and ) and give a heating margin of >200 K from melting to temp. of give a heating margin of >200 K from melting to temp. of PvapPvap = 10e= 10e--10 10 torrtorr
To be studiedTo be studiedAlloysAlloysActivation dangerActivation dangerCircuit materials for chemical compatibilityCircuit materials for chemical compatibilityThermal propertiesThermal propertiesPhysical properties for liquid curtain or filmPhysical properties for liquid curtain or filmAvailability Availability
Tm (K) Tm (°C) Z A ρ, Density A 1/3 / ρ 1 / Z10e-10 torr 10e-9 torr 10 torr kg/m³ @ Tm