Impact of the cold regenerator meshes geometry on low

temperature Pulse Tube performancesD. Dherbécourta, S. Martina, I. Charlesa, J-M Duvala, J. Andréb, C. Danielb

aCEA-Grenoble / UGA / IRIG / Département des Systèmes Basses Températures, 17, rue des Martyrs, F-38054 Grenoble, France

bCNES Toulouse, F-31055 Cedex 4, France

ATHENA

Parasitic heat

losses

Half cold

regenerator

Full cold

regenerator

Thickness 0.88 157 mW ± 10 mW 151 mW ± 10 mW

Thickness 0.82 152 mW ± 10 mW 170 mW ± 10 mW

0

10

20

30

40

50

0 10 20P.Δ

P

(bar²

)

Q (Nm3/h)

Half regenerator 0.88Half regenerator 0.82Full regenerator 0.88Full regenerator 0.82

CONTEXT – Pulse Tube coolers in space missions

CONCLUSION

This fundamental project studied the cold regenerator

meshes geometry influence on the PT performances. An

optimal meshes thickness has been highlighted, depending

on the operating conditions (temperature).

When the meshes thickness is optimized, the order of

magnitude of the power gain (50 mW) is not negligible

compared to the operating conditions of the initial 15 K pulse

tube cooler (400 mW).

A combination of this results with regenerator materials

studies would much more improve the basic 15 K pulse tube

cooler performances.

RESULTS - Impact on performances

BREADBOARD - Coaxial heat intercepted PT

ACKNOWLEDGEMENTS

This work is being conducted with a partial support of

CNES. The experimental work at CEA/SBT has been

shared by Camille Choupin, Thibault Romand and Julien

Inigo whose contributions to this project are greatly

appreciated.

Hot regenerator

Cold

regenerator

2 compressors

Input power 100 W

Active phase shift

Cold tip

300K

Fixed temperature

(50, 80 or 120K)

0

40

80

120

160

200

0.8 0.9 1

Cold

pow

er

availa

ble

at

15K

(m

W)

Normalized thickness (-)

Full cold regenerator

Half cold regenerator

Decreasing thickness = more meshes

→ Competition between physical effects

20

22

24

26

28

30

0.8 0.9 1

Cold

tip

tem

pe

ratu

re w

hen h

eate

d a

t 1W

(K

)

Normalized thickness (-)

Full cold regenerator

Half cold regenerator10

11

12

13

14

15

0.8 0.9 1

Low

est

tem

pera

ture

(K

)

Normalized thickness (-)

Full cold regenerator

Half cold regenerator

Optimal thickness of the half cold regenerator depends on the temperature

< 0.8 at low temperatures, around 0.85 at 15 K and about 0.9 up to 25 K

Optimal thickness of the upper part of the cold regenerator always < 0.8

Project: Fundamental work on the PT performances

based on a 15 K PT design

• Less dead volume

• More thermal capacity

• Extended exchange surface

Woven mesh

Scientific space missions use extremely

sensitive detectors (X-Ray, infrared),

requiring power at very low temperature

(< 100 mK)

Precooling at 15 K

with Pulse Tube

coolers

Complex cryogenic chain to obtain such temperatures

Comparison with

reference

Half cold

regenerator

Full cold

regenerator

Thickness 0.88 - 3.2 % - 8.6 %

Thickness 0.82 - 8.2 % - 9.9 %

Study on the geometry of the cold regenerator meshes

(decreasing thickness = increasing meshes number)

GEOMETRY - Cold regenerator

Reference cold

regenerator(Thickness = 1)

Thickness 0.88 0.82

Comparison with

reference

Half cold

regenerator

Full cold

regenerator

Thickness 0.88 + 5.6 % + 15.6 %

Thickness 0.82 + 14.6 % + 18.4 %

• More pressure drop

• Increasing conduction ?