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Publications - Thales Cryogenics

SPIE 2009 – Update on Thales Flexure bearing coolers and drive electronics

Thales Cryogenics has a long background in delivering cryogenic coolers with an MTTF far above 20.000 hrs for military, civil and space programs.  Developments in these markets required continuous update of the flexure bearing cooler portfolio for new and emerging applications.  The cooling requirements of new application have not only their influence on the size of the compressor, cold finger and cooling technology used but also on the integration and control of the cooler in the application.
Thales Cryogenics developed a compact Cooler Drive Electronics based on DSP technology that could be used for driving linear flexure bearing coolers with extreme temperature stability and with additional diagnostics inside the CDE.  This CDE has a wide application and can be modified to specific customer requirements.
During the presentation the latest developments in flexure bearing cooler technology will be presented both for Stirling and Pulse Tube coolers.  Also the relation between the most important recent detector requirements and possible available solutions on cryocooler level will be presented.
Keywords: Cryocoolers, reliability, miniature, robustness.

Original publication: Proc. SPIE 7298

D. Willems, T. Benschop, W. v.d. Groep, J. Mullié, H. v.d. Weijden*, M. Tops

THALES Cryogenics BV, Eindhoven, The Netherlands

SPIE 2009 – Six Sigma method applied to cryogenic coolers assembly line

Six Sigma method have been applied to manufacturing process of a rotary Stirling cooler: RM2. Name of the project is NoVa as main goal of the Six Sigma approach is to reduce variability (No Variability). Project has been based on the DMAIC guideline following five stages: Define, Measure, Analyse, Improve, Control. Objective has been set on the rate of coolers succeeding performance at first attempt with a goal value of 95%. A team has been gathered involving people and skills acting on the RM2 manufacturing line. Measurement System Analysis (MSA) has been applied to test bench and results after R&R gage show that measurement is one of the root cause for variability in RM2 process. Two more root causes have been identified by the team after process mapping analysis: regenerator filling factor and cleaning procedure. Causes for measurement variability have been identified and eradicated as shown by new results from R&R gage. Experimental results show that regenerator filling factor impacts process variability and affects yield. Improved process haven been set after new calibration process for test bench, new filling procedure for regenerator and an additional cleaning stage have been implemented. The objective for 95% coolers succeeding  performance test at first attempt has been reached and kept for a significant period. RM2 manufacturing process is now managed according to Statistical Process Control based on control charts. Improvement in process capability have enabled introduction of sample testing procedure before delivery.

Original publication: Proc. SPIE 7298

Lean-Marc VENTRE, Michel GERMAIN-LACOUR, Jean-Yves MARTIN, Jean-MARC CAUQUIL, Tonny BENSCHOP, Rene GRIOT

THALES Cryogénie SA, Blagnac Cedex, France