原创 Rakon for Aerospace <二>

ultra  stable   Quartz  Crystal  OSCILLATOR

Thermal effect in the Rakon USO
The requirement of thermal controlled precision is conducted to a thermal structure with a Dewar vessel.  Then to meet space requirements, a mechanical structure has been designed to provide resistance to space conditions,Once combined, these two structures conduct to impose a temperature distribution on the resonator illustrated by fgure 4.
The resonator used in Rakon¡¯s USO is a quartz crystal with a QAS structure

New tool to study the USO
To better evaluate the mechanical impact of the structure on the crystal resonator, a simple thermal study is not good enough. A new tool using a well known quartz theory \[6-8] has been developed. To verify its precision, a comparison has been made with the experimental results of Ratajski \[9] and this tool. Figure 5 shows the related results. The graphs show there is a good correlation between the experimentation and the simulation. 

Results
Work carried out using the different approaches on the possible interactions of the various parts of the USO, was conducted to make signifcant progress in understanding the restrictive phenomenon. A USO modifcation has been made to minimise this phenomenon which (with regard to thermal sensitivity), has enabled the best performance achievable from a USO, 5.10-14/¡ãC on Rakon¡¯s USO. Figure 6 provides evidence of  these results.

Conclusion

The results obtained from this study show a significant improvement in the  comprehension of one restrictive multi- physics phenomenon. The new performance achieved of  5.10-14/°C, is the  best performance achieved by any  space USO globally. This is a great development prior to Rakon beginning the  next stage of downsizing the  USO structure.

References:

1:V Candelier, J Lamboley, G Marotel, P Canzian and P Poulain, ’Recent Progress in Ultra Stable Oscillators for Space: On Board and Ground Applications’, 15th EFTF 2001

2.V Candelier, P Canzian, J Lamboley, M Brunet, G Santarelli, ’Space Qualified 5 MHz  Ultra Stable Oscillators’ IEEE EFTFand IFCS 2003.

3.L Schneller, S Galliou,  B Dulmet, P Canzian, V Candelier and G Cibiel, ’The Effect of Quartz Crystal Thermal Structure on Performance in Ultra Stable Oscillators’, EFTF  8pp, 2008

4..L Schneller, ’Contribution à l’élaboration d’un Oscillateur Ultra Stable Spatial Miniature : Etude et réduction de la sensibilité thermique’, Thèse 181pp, Université de Franche-Comté, 2009

5 S Galliou, ’Thermal Behaviour Simulation of Quartz Resonators in an Oven Environment’, IEEE UFFC, vol 42 no 5 pp 832-839, 1995

6.F Deyzac, ’Finite Elements Method Modelling of Accelerometric and Barometric Sensitivity of Quartz Resonators’, 7th EFTF pp 291-295, 1993

7.J Kosinski,  R Pastore, X Yang, ’Stress induced frequency shifts in Langasite Thickness-mode Resonators’, IEEE IFCS pp 716-722, 2003

8..J Baumhauer and H Tiersten, ’Nonlinear Electroelastic Equations for Small Fields superposed on a Bias’, J. Acoust. Soc. Am., vol 54 no 4 pp1017-1034, 1973

9.J Ratajski, ’Force-Frequency Coefficient of singly Rotated Vibrating Quartz Crystals’, IBM journal pp 92-99 1968

10. J Norton, J Cloeren and P Sulzer, ’Brief History of the Development of Ultra Precise Oscillators for Ground and Space Applications’, IEEE 50th IFCS pp 47-57, 1996

Jesse Wu  MSN：jesse-wu@hotmail.com MT:13032180675 QQ:81643653