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Payload

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Payload

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  1. Payload TDLAS and Accelerometers

  2. Outline Which water lines to choose? TDLAS geometry, base components TDLAS failure modes Accelerometer requirements Possible accelerometers & support equipment Concluding remarks Future work

  3. HITRAN Database • High-resolution Transmission Molecular Absorption Database • Using JavaHAWKS software to select from 35 atmospheric gases and respective isotopes

  4. Water Absorption Lines Selection Criteria • Water isotope selection • Water 161 abundance of 99.73 % • 14000 spectral lines in the NIR region • Line Strength and intensity • Absorption line isolation • MLH: potential lines 1.370 μm and 1.877 μm

  5. Spectral Line Selection 1.370 μm 1.877 μm [1] [1]

  6. TDLAS Design Instrument Design Considerations: • Spectral line intensity • Laser diode availability • Increased path length via reflections • Beer’s Law: • Potential mirror materials for NIR detection • Zerodur, Silicon Carbide

  7. Geometry • Path length 139.5 cm • Laser beam width • 1.5 μm x 3.0 μm • Culminating lens • Reflection point separation of 1 mm • Directing mirror angle of 3.8° by 1.9° Top View* 1.5 cm 3 cm End View* 0.5 cm 1.5 cm *Not to scale, used to illustrate path direction and mirror placement

  8. Operational Components • Light Source • 1.877 μm • DFB laser diode • InGaAsphotodetector • Thermal control • Laser and detector • Tolerance of ±0.1 °C • Laser control unit • Wave form generator [2]

  9. Comparison

  10. Failure Modes • Structural failure • Physical fracture of the instrument • Shifting of mirrors, laser source or detector • Incorrect water isotope selection • 162, 171, 172 etc. • Detection limit too high

  11. Accelerometer Selection Requirements Measure a shock over 10 μs 30000 g capability 25 kHz data acquisition rate Hermetically sealed Space qualified

  12. Potential Candidates

  13. Analysis Equipment Vibrations Research Corp. • Shock and Transient Capture software • Unit Cost: $2500 US each Dytran • 10-32 to BNC Hypershock Cables and 4 channel current source • Total cost of $814 Cdn

  14. Failure Modes Off axis impact, resulting in the shearing of the piezoelectric from the base Cable connection severed due to impact Excitation at the natural frequency Shearing of the mounting stud from the structure

  15. Conclusions TDLAS structure will require custom manufacturing for the mirror positioning and geometry Laser source for 1.877 μm is COTS COTS accelerometers are available from Endevco, Dytran and Kistler

  16. Future Work Find the energy drop in laser intensity Refine the geometric design of the TDLAS Select a material and suitable reflective coating Size the detector for the TDLAS Continue with accelerometer selection Verify quotes and delivery times for accelerometers

  17. References [1] L.S. Rothmana, D. Jacquemarta, A. Barbeb, D. Chris Bennerc, M. Birkd, L.R. Browne, M.R. Carleerf, C. ChackerianJr.g, K. Chancea, L.H. Couderth, V. Danai, V.M. Devic, J.-M. Flaudh, R.R. Gamachej, A. Goldmank, J.-M. Hartmannh, K.W. Jucksl, A.G. Makim, J.-Y. Mandini, S.T. Massien, J. Orphalh, A. Perrinh, C.P. Rinslando, M.A.H. Smitho, J. Tennysonp, R.N. Tolchenovp, R.A. Tothe, J. Vander Auweraf, P. Varanasiq, G. Wagnerd, “The HITRAN 2004 molecular Spectroscopic Database”, J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005) [2] T. Le Barbu, I. Vinogradov G. Durry, O. Korablev, E. Chassefie`re, J.-L. Bertaux, “TDLAS a laser diode sensor for the in situ monitoring of HO and CO and their isotopes in the Martian atmosphere”, Advances in Space Research 38, 718-725 (2006) [3] C.R. Webster, G.J. Flesch, K. Mansour, R. Haberle, J. Bauman, “Mars Laser Hygrometer”, Applied Optics 43-22 (Aug 1/2004)

  18. Questions