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Publications - Thales Cryogenics

SPIE Paper – Robust Stirling coolers for sensing in extreme environmental conditions

With the achievements made in the last decade with respect to reliability and cryogenic performance, the use of Stirling
and Pulse Tube cryocoolers for new application areas has become viable. Thales Cryogenics has been challenged by its
customers to deliver robust and compact solutions for a variety of applications.
The test approaches within the Thales Environmental Test Lab – a centre of excellence within the Netherlands – have
been refined significantly, departing from the classical robustness testing principles, which typically consist of
submitting the product to an environment with a compressed energy allocation – shorter time duration and higher PSD
An overview is given of recent activities at Thales Cryogenics regarding the development and testing of linear Stirling
cryocoolers for extreme environmental conditions. A novel cooler will be presented that has been developed specifically
for operation in high ambient temperature conditions. In addition, an overview will be given of ongoing test &
development activities regarding coolers for operation under severe mechanical loads. Design aspects, margin
philosophy, test plans (including robustness testing) and test results will be presented.
Keywords: stirling, linear, cryocooler, robustness, temperature, shock, vibration

R. Arts, D. Willems, J. Mullié, R. van Leeuwen, P. Bollens, T. Benschop, G. de Jonge
Thales Cryogenics B.V. (Netherlands)


2018-04-18 SPIE Paper – RMs1 – The state of the art SWaP cooler

For five years, Thales Cryogenics has led a new development cycle in order to design and deliver a new generation of
SWaP cryocoolers. Both linear and rotary Stirling coolers have been developed.
SWaP coolers are especially designed to cool the emerging High Operating Temperature IR detector (HOT). Insofar as
optimal detector performance for HOT technologies are still challenging, Thales forced himself to develop a rotary
cooler that can cool detector at intermediate cold temperatures, ie. 90 to 140K, even if the optimal performances are
reached for 150K.
A first demonstrator was shown during the SPIE2015 exhibition. That prototype was useful to investigate technologies to
be introduced in order to drastically improve the compactness and the weight. Both aspects were reduced by 50%
compared to a legacy RM2. The achieved compactness was identified as an optimal trade-off between mass and volume
versus the associated production costs.
Last year, Thales worked on new prototypes of the RMs1 SWaP rotary cooler. That product is the results of the previous
R&T and design phases, on one hand, and the adoption of generic standards on interfaces like the cold finger in order to
simplify integration – and thus reduce overall cost – by our customers on the other hand. Associated performances were
presented and commented.
The current paper is focused on the qualification results obtained at the end of 2017. Especially, the available cooling
power versus the cold temperature will be shared, next to other important key cryogenics performances such as the cool
down time for dedicated detectors, characterized by a thermal masses and operational temperatures. Moreover, a
particular effort has been made on other “soft” performances, in order to greatly improve the user experience, that is to
say noise and induced vibrations. At last, first lifetime figures for the RMs1 are also presented and commented.
As a conclusion, the compliance of the RMs1 performances with expectations for HOT IR detectors is discussed, in
order to highlight the next steps of the development of the SWaP cryocoolers.
Keywords: Cryogenics, Rotary stirling cooler, IR detector, HOT, SWaP

Christophe Vassea, Cédric Seguineaua, Jean-Yves Martina, Sébastien Van-Ackera, Mikel Sacaua,
Julien Le Bordaysa, Thierry Etchanchua, Christian Abadiea, Sylvain Chaumeaua, Tonny Benschopb
aThales LAS France S.A.S., 4 Rue Marcel Doret BP70022, F-31701 Blagnac FRANCE;
bThales Cryogenics B.V., Hooge Zijde 14, 5626 DC Eindhoven, Netherlands.

SPIE Paper – Lifetime Validation of High Reliability Rotary Cryocoolers for specific customer profiles

The cooler reliability is a major performance requested by the customers, especially for 24h/24h applications, which are
a growing market. Thales has built a reliability policy based on accelerate ageing and tests to establish a robust
knowledge on acceleration factors. The current trend seems to prove that the RM2 mean time to failure is now higher
than 30,000hr. Even with accelerate ageing; the reliability growth becomes hardly manageable for such large figures.
The paper focuses on these figures and comments the robustness of such a method when projections over 30,000hr of
MTTF are needed.
Keywords: Cryogenics, MTTF, reliability, Weibull, Weibayes, Stirling, Cooler, IR detector.


Jean-Marc Cauquila, Cédric Seguineaua, Christophe Vassea, Gaetan Raynala, Tonny Benschopb
aThales LAS France S.A.S., 4 Rue Marcel Doret, CS70022, F-31701 Blagnac France;
bThales Cryogenics B.V., Hooge Zijde 14, 5626 DC Eindhoven, Netherlands