1 EUROnu design System target + horn First thermal calculations on the target made of aluminium G. Gaudiot 02/06/2010 Strasbourg.

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EUROnu design

System target + horn

First thermal calculations on the target made of aluminium

G. Gaudiot 02/06/2010 Strasbourg

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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