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Carrie A. Kauffman, Kyle N. Crabtree, Benjamin J. McCall Department of Chemistry, University of Illinois June 23 rd, 2009 A Continuous Supersonic Expansion.

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Presentation on theme: "Carrie A. Kauffman, Kyle N. Crabtree, Benjamin J. McCall Department of Chemistry, University of Illinois June 23 rd, 2009 A Continuous Supersonic Expansion."— Presentation transcript:

1 Carrie A. Kauffman, Kyle N. Crabtree, Benjamin J. McCall Department of Chemistry, University of Illinois June 23 rd, 2009 A Continuous Supersonic Expansion Discharge Nozzle For Rotationally Cold Ions

2 Motivation Molecular ions ◦ Organic Reaction Intermediates ◦ Combustion ◦ Atmospheric Chemistry ◦ Interstellar Chemistry Simulation of N 2 + of the A 2 ∏ u – X 2 ∑ g + (4-0) +

3 For more on the progress of SCRIBES, stay for the next two talks. Supersonic Source

4 Supersonic Expansion Barrel Shock High Pressure Gas Small Orifice Adiabatic Process, dq = 0 dU = dq –dw dU = -PV T vib >> T rot > T trans, where T rot ~ K Low Pressure Region Mach Disk

5 Compatible with SCRIBES Leak tight Robust Modular Maximize ion density Design Considerations

6 Previous Reported Discharge Designs

7 First Generation - Corona Engelking, P.C.; Corona Excited Supersonic Expansion. Rev. Sci. Instrum., 1986, 57, AdvantagesDisadvantages ContinuousMaterials Chosen No modular components Compatibility

8 Slit Design Broks, B.; Brok, W.; Remy, J; van der Mullen, J.; Benidar, A.; Biennier, L. & Salama, F.; Modeling the Influence of Anode-Cathode Spacing in a Pulsed Discharge Nozzle. Spectrochim Acta B, 2005, 60, AdvantagesDisadvantages Materials ChosenIntegration with SCRIBES Clustering Pulsed

9 Nozzle Design McCarthy, M. C., Chen, W.; Travers, M. J. & Thaddeus, P. Microwave Spectra of 11 Polyyne Carbon Chains. Astrophys. J. Suppl., 2000, 129, AdvantagesDisadvantages Compatibility with SCRIBESPulsed ModularMaterials

10 Design 1-3 Atmosphere of backing pressure Orifice Size: 250 to 1000 micron with varying geometry Typical Chamber Pressure 100 mTorr

11 Source Nitrogen Gas Running Voltage: -200 to -500 V Running Current: 30 mA Operation Time: 100+ Hours

12 Characterization of the source Ion Current Optimization of Cooling Capabilities

13 Summary Design Continuous Supersonic Expansion Nozzle Discharge Modular Self-Aligning Robust

14 Acknowledgements SCS Machine Shop McCall Research Group Ben McCall


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