2. Laser-Induced Fluorescence for Plasma Diagnostics Designing and Testing an Optical Probe for Advanced Plasma Studies Stephanie Sears Advisor: Dr. Walter Gekelman

3. Overview  What is a plasma?  What kind of plasma was used for this research?  How was this plasma generated?  What exactly is LIF?  How was the experiment constructed? The laser The laser The probe The probe Data Collection Data Collection  What were the results?  What were some of the problems?  How does this contribute to further research in plasma physics?  What is the next step?  Conclusions

6. Helium Plasma

7. Neon Plasma

8. Specifics of Our Plasma Fully-ionized argon (ArII) Dimensions= Density= Approximate electron temperature= Predicted ion temperature=

9. Creating the Plasma The plasma is pulsed Field Strength= Created with an electron beam

10. The Machine Schematic North South

11. Machine Specifications 18 meters in length, 1 meter in diameter 90 magnetic coils generate fields between 0.05 and 4 kG Barium oxide-coated nickel cathode Molybdenum mesh anode 0.55 meter cathode-anode separation 450 radial ports 60 rotating flanges 4 mechanical pumps 2 turbo pumps 2 portable vacuum stations Computer controlled stepping motors Available working gases include helium, neon, argon, and hydrogen

12. The Machine Itself

14. The Cathode

15. The Anode

16. Inside the Chamber

17. What is Laser-Induced Fluorescence (LIF)?

18. Allowed Transitions of Argon II

19. Simple Energy-Level Diagram

20. Theoretical Spectrum

21. Actual, Doppler-Broadened Spectrum

22. Illustration of the Doppler Effect

23. Relation of Optical Intensity to Wavelength

24. Why is this worth looking at?

25. The Experimental Set-Up

26. Timing Diagram

27. The Laser

29. The Probe (Original Design)

30. Actual Design

31. Data Collection

32. The Data

33. Interpreting the Data

35. Problems To Overcome Very low signal-to-noise ratio Huge amount of scattered light Poor alignment of fiber with laser sheet The laser itself

36. Ways to Improve LIF Observation Better Filter Amplifier Better Probe Design

37. Design for a Future Probe

38. Conclusions

39. Acknowledgements and Thanks Dr. Walter Gekelman-Advisor Stefan Grunspan and Brett Jacobs-UCLA students Marvin Drandel-LAPD technician Everyone else on the UCLA plasma team Fellow REU students and friends

40. The End The End