G Riddone 25062010 CLIC meeting Contribution from R Nousiainen J Huopana T Charles Content Recall of main issues Recall of module heat dissipation Module cooling scheme Thermomechanical analysis ID: 513392
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Slide1
Accelerating structure thermo-mechanical behavior
G. Riddone. 25.06.2010
CLIC meeting
Contribution from R. Nousiainen, J. Huopana, T. CharlesSlide2
Content
Recall of main issuesRecall of module heat dissipation
Module cooling schemeThermo-mechanical analysis: Accelerating structuresTwo-beam modulesRemarks
GR, BE-RF, 25/06/2010
2Slide3
Main issues
Tolerances must be preserved in static
and dynamic conditions (RF and beam dynamics constraints):
shape accuracy for machining: ± 2.5
m
m,
pre-alignment: 14 um @ 1
s
water
induced vibrations
Optimization of several parameters: temperature stabilization, pressure drop, volumetric flow, Re, heat transfer coefficient,… Compromise between opposite requirements from several technical systems
GR, BE-RF, 25/06/2010
3Slide4
Accelerating structure heat dissipation
Accelerating structure
Thermal load is
not
constant through an accelerating structure
Considered
unloaded condition and loaded
conditions
Cell-by-cell heat dissipation
EDMS 964717
Distribution of heat flux over
480 mm: superstructure
Loaded 672 W
Unloaded 821W
GR, BE-RF, 25/06/2010
4Slide5
Module heat dissipation (water cooled)
For details, see EDMS# 910399
GR, BE-RF, 25/06/2010
5Slide6
CLIC Workshop 2007
R. Nousiainen
J.
Inigo-Golfin
Total per
linac
(2007): 65 MW
Action:
reduce mass-flow rate, increase temperature difference between supply and return pipes
GR, BE-RF, 25/06/2010
6
Baseline: one access point for inlet and outlet pipesSlide7
Module cooling scheme
Twater_in
=
25
˚
C
[
± 2 ˚C] Re = 5800 (d = 7 mm)h = 3750 W/m
2
/K
V= 70 l/h [per AC. STR.]V = ~350 l/h [per MODULE]V = 3500 m/h [per LINAC]Still one inlet/outlet access point close to IP (§CES WG Dec 2008)
45 ˚C
35 ˚C
25 ˚C
45 ˚C
25 ˚C
GR, BE-RF, 25/06/2010
7Slide8
Super accelerating structure
GR, BE-RF, 25/06/2010
Max 39.7 °C
Max 38 °C
Unloaded
Loaded
[K]
T
emperature
difference
Unloaded to Loaded
Thermal analysis
8
1.9 K
0.8 K Slide9
Accelerating structure
GR, BE-RF, 25/06/2010
beam
Transverse movement induced by the thermal expansion (volumetric flow can be adjusted to limit this effect)
Max 2,5
µm
Beam pipe deformation:
unloaded to loaded structural effect
Structural analysis
Fixed
9Slide10
Two-beam module: definition
TMM model:
Static thermalStatic structuralLoading conditionsGravity
Vacuum
Nominal unloaded RF load
8 accelerating structures brazed into one 2-m long unit
GR, BE-RF, 25/06/2010
Component
Material
E [
Gpa
]
α [µ
m/m-°C]
Girder
SiC
420
5
RF structure supports
Al
EN AW 7075
72
23.6
RF structures
Cu
OFE
110
16.4
Vacuum system
Stainless steel
200
17.3
Geometry of
Baseline configuration
10Slide11
Two-beam module: unloaded case
GR, BE-RF, 25/06/2010
Surrounding air: 30˚C
Girders are at different temperature, reference T = 25 ˚C
Hottest spot in the AS – 40˚C (loads omitted)
Thermal analysis
11Slide12
GR, BE-RF, 25/06/2010
Notice lateral deformation and wave guide deformation
Gravity + Vacuum
Two-beam module: unloaded case
Gravity + Vacuum + RF (unloaded)
Structural analysis
12Slide13
Influence of T difference
2007
2010
V = 2 m/s
Tunnel pipe diameter: case of unique access point
GR, BE-RF, 25/06/2010
13Slide14
GR, BE-RF, 25/06/2010
14Slide15
Remarks
Estimation of power dissipation: temperature difference across structures compromise between several technical constraints
Thermal issues are big challenge for micrometric precision of structuresDuring RF ramp up ~15 K variation in temperature is expected
Large deformations
Unloaded to loaded ~2 K variation in temperature
Thermally caused deformations linearly proportional to temperature variation
Minimize temperature fluctuations mass-flow adjusted accordingly
Module thermo-mechanical analysis based on input from technical experts
Combines separate simulations results
Shows fundamental thermo-mechanical behaviorHelps defining current improvement pointsVacuum and RF ramp up (thermal variations) causes significant deformations Thermo-mechanical effect mitigation is essentialGR, BE-RF, 25/06/201015