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A Continuous Supersonic Expansion Discharge Nozzle For Rotationally Cold Ions

A Continuous Supersonic Expansion Discharge Nozzle For Rotationally Cold Ions. Carrie A. Kauffman , Kyle N. Crabtree, Benjamin J. McCall Department of Chemistry, University of Illinois June 23 rd , 2009. Motivation. Molecular ions Organic Reaction Intermediates Combustion

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A Continuous Supersonic Expansion Discharge Nozzle For Rotationally Cold Ions

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

  2. Motivation • Molecular ions • Organic Reaction Intermediates • Combustion • Atmospheric Chemistry • Interstellar Chemistry Simulation of N2+ of the A 2∏u – X 2∑g+ (4-0) +

  3. Sensitive Cooled Resolved Ion BEam Spectroscopy Supersonic Source For more on the progress of SCRIBES, stay for the next two talks.

  4. Supersonic Expansion Barrel Shock Mach Disk Low Pressure Region High Pressure Gas Small Orifice • Adiabatic Process, dq = 0 • dU = dq –dw • dU = -PV • Tvib >> Trot > Ttrans , where Trot ~ 0.5-30 K

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

  6. Previous Reported Discharge Designs

  7. First Generation - Corona Engelking, P.C.; Corona Excited Supersonic Expansion. Rev. Sci. Instrum., 1986, 57, 2274-2277.

  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, 1442-1449.

  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, 611-623.

  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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