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Publications - Thales Cryogenics

Validation of accelerated ageing of Thales rotary Stirling cryocoolers for the estimation of MTTF – RM2 Stirling Cryocooler

Most of the time, the cryocoolers are one of the components dimensioning the lifetime of cooled IR detectors, its reliability is thus one of its most important parameters. This parameter has to increase in order to answer market needs. To do this, the data for identifying the weakest element determining cooler reliability has to be collected. Yet, data collection based on field return are hardly usable due to lack of information. A method for identifying the improvement in reliability has then to be set up which can be used even without field return. This paper describes the resulting method followed by Thales Cryogénie SAS and its application to RM2 coolers. 1- A database has been built from extensive expertizes of RM2 failures occurring in accelerate ageing. Failure modes have been identified and corrective actions achieved. 2- Specific changes have been introduced to improve efficiency. The link between efficiency and reliability will be described in this paper. The work on the two axes – weak spots for cooler reliability and efficiency – permitted us to increase in a drastic way the MTTF of the RM2 cooler. Huge improvements in RM2 reliability are actually proven by both field return and reliability monitoring. These figures will be discussed in the paper.

J.M. Cauquil, C. Seguineau, J.-Y. Martin (Thales Cryogénie SAS France)

T. Benschop (Thales Cryogenics B.V. Netherlands)

Validation of accelerated ageing of Thales rotary Stirling cryocoolers for the estimation of MTTF – RM3 Stirling Cryocooler

The cooled IR detectors are used in a wide range of applications. Most of the time, the cryocoolers are one of the components dimensioning the lifetime of the system. The current market needs tend to reliability figures higher than 15,000hrs in “standard conditions”. Field returns are hardly useable mostly because of the uncertain environmental conditions of use, or the differences in user profiles. A previous paper explains how Thales Cryogenics has developed an approach based on accelerated ageing and statistical analysis [ 1]. The aim of the current paper is to compare results obtained on accelerated ageing on one side, and on the other side, specific field returns where the conditions of use are well known. The comparison between prediction and effective failure rate is discussed.

C. Seguineau, J.M. Cauquil, J.-Y. Martin (Thales Cryogénie SAS France)

T. Benschop (Thales Cryogenics B.V. Netherlands)

Rotary Monobloc Cooler RM3

Compatible to main applications

Having an electronic digital driver integrated in the RM3 cooler brings out many advantages for functionality, performance and ergonomics aspects. Initially RM3 cooler driver has been developed and designed by a supplier and both hardware and firmware designs were proprietary to this subcontractor. Although behavior of the cooler has been proved remarkably reliable and efficient at both lab and field level some improvements were expected. Thales took then the opportunity to fund development of its own proprietary driver, keeping control on the product and facilitating future improvements.

 

SPIE-DSS 2016 – Advantages of high-frequency Pulse-tube technology and its applications in infrared sensing

The low-frequency pulse-tube cryocooler has been a workhorse for large heat lift applications. However, the highfrequency pulse tube has to date not seen the widespread use in tactical infrared applications that Stirling cryocoolers have had, despite significant advantages in terms of exported vibrations and lifetime.
Thales Cryogenics has produced large series of high-frequency pulse-tube cryocoolers for non-infrared applications since 2005. However, the use of Thales pulse-tube cryocoolers for infrared sensing has to date largely been limited to high-end space applications.
In this paper, the performances of existing available off-the-shelf pulse-tube cryocoolers are examined versus typical tactical infrared requirements. A comparison is made on efficiency, power density, reliability, and cost. An outlook is given on future developments that could bring the pulse-tube into the mainstream for tactical infrared applications.

Original publication: Proc. SPIE 9821

T. Benschop, D. Willems, J. Mullié, R. Arts
Thales Cryogenics B.V. (Netherlands)