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1
EUROnu design
System target + horn
First thermal calculations on the target made of aluminium
G. Gaudiot 02/06/2010 Strasbourg
2
Introduction
The thermal inputs on the target and the horn :
- beam on the walls of the horn- external conductor ~ 48 kW- internal conductor , cone ~ 15 kW- internal conductor , small pipe ~ 80 kW
- Joule effect in the horn conductorssignificant value only in the small pipe (« waist ») ~ 10 kW (for 6 cm diameter)
- deposited power in the target > 200 kW
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study of the target which receives most of the heat
• Previous calculations with a target made of graphite , cooling by an important flux of helium gastemperature : about 1000°C
• Target in aluminium : maximal temperature 150 - 200°C
does a water cooling allow to maintain this value for a power of 200 kW ?
→ very simple model in a permanent working.
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First model of a target in aluminium axi symetric
0 200 400 500 mm
30
10
5
R mm
3,5 W/mm3 1,5 W/mm3 total : 220 kW
hc = 5000 W/m².K t∞ 18°C (water spray)
Hypothesis : as we want a maximal temperature of 200 °C , the exchange by rayonnement is not considered
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Temperature distribution in the target
Maximal temperature 1726 °C !
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• With ridges on external radius
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8
exchange area + 60%
max. temperature : 1476 °C
• diminution of the power density
1,7 W/mm3 in a cylinder Ø 20 long. 400 (214 kW) → 1171 °C
0,44 W/mm3 in a cylinder Ø 40 long. 400 (221 kW) → 853 °C
→ impossibility to cool the target with water sprays only
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Just a mechanical idea
water flowing inside pipes : we can reach coefficients of heat-transfer hc > 20000 W/m².K
water output
water input
square target !?
long drillings ?
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1647 °C 1319 °C maximal temperatures
hc = 20000 W/m².K t∞ 18°CØ8
2x Ø6
P = 3,5 W/mm3 in Ø10 et 1,5 W/mm3 between Ø10 and Ø20
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maximal wetted area
flowing water
target Ø40 mm
internal conductor of the horn
water sprays
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5000 W/m².K
20000 W/m².K
Axi symetrical model target + internal horn wall
maxi 1082 °C
Temperature distribution for 200 kW (3,5 et 1,5 W/mm3)
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« manual » calculation on a transversal section
Tmax T1 Tp
R1 Re
Volume power Pv (per unit of length Pvl)
λ
T∞ hc
Tmax – T1 = Pvl / 4π.λ
T1 – Tp = Pvl . ln(Re/R1) / 2 π.λ
Tp - T∞ = Pvl / 2π.Re.hc
Pv = 2.105 W l = 0,4 m Pvl = 5.105 W/m
Re = 0,02 m R1 = 0,005 m λ = 170 W/m.K (alloy of aluminium) hc = 10000 W/m².K
Tmax – T1 = 234,1 °C T1 – Tp = 648,9 °C Tp - T∞ = 397,9 °C Tmax - T∞ = 1280,9 °C
material (λ) material (λ) Re , hc ←┐ Re/R1 ←┘ parameters
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It is impossible to keep a low target temperature with water cooling if :
• we don’t reduce the power density (for exemple by using at the same time 4 systems target + horn)
• we don’t put the cooling closer to the area of maximal power density
• may be , we don’t use a better thermal conductor
• Consider the other material parameters (density , …) in order to reduce the total deposited power in the target
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Possible improvements
• Thermal transfer by phase change : hc > 105 W/m².KTp - T∞ = 39,8 °C pour hc = 105 W/m².K
• Diminution of the target diameter , where the density is maximal → to reduce ln(Re/R1) and T1
• Water sprays in front ? → to cool the impact of the beamis it acceptable for physics ?
• Other materials for a system target + horn (or for target only)
Beryllium melting point : 1285 °C λ = 210 W/m.K
AlBeMet (62 % Be 38% Al) melt. point : 1082 °C « solidus 645 °C
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• Beryllium (= glucinium)
light , density : 1,85 rigidity : + 50% / steelhigh mechanical strength
→ used in aeronauticsbut difficult welding : - welding and electron beam welding : high conductivity of Be and extensive grain growth result in brittle joint. acceptable , if mechanical strength is not very important- brazing in argon, the best joining technique
dusts (machining) and vapours very toxic
• AlBeMet® (Brush Willman)
low density too, high elastic modulus 193 GPa (almost the same as steel) and welding by the same technologies than aluminium.
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Phase diagram of aluminium – beryllium system (Elliott , IITRI)
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General concept for a steady state regime without considering the pulses
• Mechanical design• Material properties and manufacturing technology
→ acceptable temperature• Energy deposition in the target• Energy deposition in the magnetic horn (waist)• Definition of the water cooling• Calculations : - temperature distribution
- thermal strain
- stresses
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Next actions
• thin curtain of water under high pressure in front of the target → effectiveness ?
• design of a setup of sprinklers very close to the target → important coefficient of transfer (thermal study by Benjamin Lepers and help by an engineering school)
• answer to the question : is AlBeMet better than aluminium for the target (point of vue of technology, not only in theory) ?
• influence of pulses
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3D Model from the
drawings of the
CERN horn prototype
Drawing by S. Rangod (2001)
Modelizing by Valeria Zeter (IPHC)
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Aim
to have a parameterized 3D model in order to make
multiphysic calculations.
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EUROnu - la corne prototype du CERN
S.Rangod 15/05/2001
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EUROnu - la corne
vue d’ensemble
sprinklers , not represented
water inlets
water outlet
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EUROnu- la Corne
outer electrical skin
inner electrical skin
waistjacket
inner conductor connection flange
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EUROnu - la corne
Quelques détails
screw shaped neck
water inlets
glass insulator disc
water inlets
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Plaque alimentation corne_Version LAL
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Vue éclatée de la plaque d’alimentation
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Electrical connections , strip-lines