2. Axion Relics Thermal – mechanical simulation for a flange UHV 114/63 1D with copper gasket

3. Mechanical simulation goal
Simulate the deformation occurring on the copper gasket
The entity of the force characterizes and affect the thermal contact coefficient.
Required force  kN for each bolt  9.8 Nm/bolt  8 bolt  49 kN Bolt size M8x50
Conclusion Thermal contact copper gasket – ss flange
plastically deformed  approximated as perfect contact
Applied Force 49 kN
1 - 2 micrometres of def.
room temperature
copper RRR 50
Copper tube FIXED constraint
Copper tube and Flange bonded

4. Thermal simulation goal
To calculate the temperature distribution for the component connecting
the copper cavity to the magnet through the flange UHV 114/63
Inner copper cavity simulation for different heat loads: 10 mW
15 mW
20 mW
2 K
MLI insulated
Heat Load
Material used:
AISI 316 L for the tube and flanges
Copper RRR 50
Surrounding T = 70 K

5. Thermal simulations results I
Heat load 15 mW
Tmax K
Heat Load
T max
20 mW
12.7
15 mW
10.7
10 mW
9.4

6. Solutions A
Aim: to keep the copper cavity temperature as low as possible. The requested temperature is 2.0 K
Three mm-thick copper pipe added to make a thermal bridge from the helium sink up to the copper cavity
Solution: One thermal contact:
Copper bridge – 316L tube 
Extrapolated value: 1 W/Km2 and 3 W/Km2
[“Thermal boundary resistance of mechanical contact btw solids at sub-ambient temperatures” – E. Gemlin et al.]

7. Thermal simulations II
Solution: Two thermal contact considered btw copper and 316L tubes
2 K
15 mW
MLI insulated
5 mW

8. Thermal simulations results II
Heat load mW
Tmax K
Tmax K
Kcopper-ss tube 1 W/m2K
Kcopper-ss tube 3 W/m2K
Tmax – copper bridge K
Tmax – copper bridge K
Copper bridge to actively cool the electronic support

9. Solution B outer copper ring plus bayonet

10. Liquid He II
Copper ring
Cold clamps to attach cabling. To be modelled

11. Thermal simulations Solution:
Copper cylinder attached to the cold part. Di = 58 and De = (68, 80, 84, 100)mm
copper strip attached to it and working as a cold bridge for the measuring part. thickness (6, 10, 14, 28); width 25 mm. (Ω = 150, 250, 350, 700 mm2)
Thermal contact btw copper bayonet and copper measuring part: 20 mW

12. Thermal simulations Solution:
Copper cylinder attached to the cold part. Di = 58 and De = (68, 80, 84, 100)mm
copper strip attached to it and working as a cold bridge for the measuring part. thickness (6, 10, 14, 28); width 25 mm. (Ω = 150, 250, 350, 700 mm2)
Thermal contact btw copper bayonet and copper measuring part: 20 mW
Kcopper-ss tube
1 W/m2K
KSS tube - Copper sink
200 W/m2K [2]
2 K
KCopper sink - copper strip
385 W/m2K [2]
KCopper cavity- copper strip
385 W/m2K [2]
20 mW
[2] “Thermal boundary resistance of mechanical contact btw solids at sub-ambient temperatures” – E. Gemlin et al. Table 1 and Table 2
Cu/Apiezon/Cu (385 – 3300) W/m2K Force of 450 N Temperature range (1.6 – 6) K
Cu/SS W/m2K Force of 9.8 kN Temperature range (326/335) K

13. Thermal simulations results
Heat load 20 mW
Sim. IV : Tmax 4.77 K
Copper ring 58/68 mm
Copper strip 6 mm thick
Sim. V : Tmax 3.93 K
Copper ring 58/80 mm
Copper strip 10 mm thick
Sim. VI : Tmax 3.48 K
Copper ring 58/84 mm
Copper strip 14 mm thick
Sim. VII : Tmax 2.92 K
Copper ring 58/100 mm
Copper strip 28 mm thick

14. Thermal simulations Solution:
Copper cylinder attached to the cold part. Di = 58 and De = 80 mm
copper strip attached to it and working as a cold bridge up to the measuring part (cross section: 10 x 49 mm2 = 490 mm2)
Thermal contact btw copper bayonet and copper measuring part: 10 mW

15. Thermal simulations results
Heat load 10 mW
Sim. VIII : Tmax 2.55 K
Copper ring 58/80 mm
Copper strip 10 mm x 49 mm
Heat load 20 mW
Sim. VIII : Tmax 3.08 K
Copper ring 58/80 mm
Copper strip 10 mm x 49 mm

16. Thank you for the attention