alessandro bertarelli - cern · 10e-10 torr 10e-9 torr 10 torr kg/m³ @ tm bi 544 271 -4 24 806 83...
TRANSCRIPT
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
LHC Collimations Phase II:Preliminary Design meeting
LHC Collimation
Phase II
SpecificationMeeting
8th February, 2008
CERN Geneva
Alessandro Bertarelli1
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
Liquid metals compatible with UHV
303 ©
430 ©
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
912 ©
505 ©
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
Bi 544 271 -4 24 806 83 208.98 10050 5.90E-04 0.012Ga 303 30 493 538 1677 31 69.72 6095 6.75E-04 0.032In 430 157 247 286 1310 49 114.82 7020 6.92E-04 0.020Li 454 181 -2 26 716 3 6.94 512 3.73E-03 0.333Sn 505 232 347 395 1635 51 118.69 6990 7.03E-04 0.020
Interaction length param.
radiation length param.
DT m to … (K)
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
Phase II CollimationPreliminary R&D activity on materials – organization of a working group
…probably this “magic” material does not exist…we should focus our attention on a mixed approach:
NEW MATERIAL
NEW DESIGN
GOAL: identification of new suitable material(s) and/or jaw assembly integrated design
A. Bertarelli – A. Dallocchio LHC Collimation Phase II – Design Meeting – 26th November 2007
360º Jaw Concept
Possible Advantages1. Increase of collimation efficiency (Particles
are intercepted on 180º to 360º)…2. Robustness (a new collimation slit can be
used after accidental beam losses)…3. Geometric stability is improved by pressing
the jaws one against the other
Possible Disadvantages1. Loss of 1 dof (one can play with geometry of
collimation pipes)…2. Minimum aperture is fixed3. Impedance??...