1. Design Studies of a Microwave-driven Ion Source
Ying-Xing Lin
Minnesota State University, Mankato
Advisor: Vladimir Derenchuk
IUCF
August 5, 2003

3. Pre-Injector Assembly Side View

4. Cross sectional view of the plasma chamber and the extraction system
describe 4 electrodes
Boron Nitride keeps the ions from recombining into H2+

5. Beam current measured at the beam stop VS. the ion gauge pressure
This plot shows the beam current measured at the beam stop as the pressure of the ion gauge changes at different electron suppression voltages. The Pressure is changed by bleeding in nitrogen gas through a needle valve closed to the extraction regiony

6. Goals Minimize N2 gas usage in the vacuum chamber
Improve the beam intensity
Minimize the spread of the beam

7. PBGUNS Particle Beam GUN Simulation
the computer code of PBGUNS is written in FORTRAN and is about 53,000 lines long
used for the simulation of axisymmetric and 2-D electron and ion extraction problems: relativistic, thermionic, field emission, sputter ejection, positive and negative ion extraction…
solves Poisson’s Equation using iterative relaxation techniques on a rectangular array of squares
determines the plasma boundary for plasma sources and does not require a “curvature” or any other knowledge of the beam or plasma

9. Result of PBGUNS simulation
define angle
Define 4 electrodes, angle, red line, green line,

10. Result of PBGUNS simulation

11. multiplier 4 95% of the rays are included in the ellipse

12. dR/dz determinses how parallel the beam is
smaller the value, more parallel the beam is
Rmax value determines the size of the beam
smaller the value, smaller the beam

13. Angle=66 degrees, Distance = 5.5mm
define angle

14. 6.5mm

15. 7.5mm

16. 8.5mm

17. 9.5mm

18. 10.5mm

19. 11.5mm

20. 12.5mm

21. 13.5mm

22. 14.5mm

23. 15.5mm

24. 5.5mm

25. 6.5mm

26. 7.5mm

27. 8.5mm

28. 9.5mm

29. 10.5mm

30. 11.5mm

31. 12.5mm

32. 13.5mm

33. 14.5mm

34. 15.5mm

38. Determine the effect of plasma current

39. with 2 different mass, see how many percentage of heavier mass should be added to have the smallest emittance and beam size

40. Angle = 80 degrees

41. Angle = 54 degrees

44. The Final Design

46. 20 mm length

47. 100 mm length

48. Conclusion
Even though the scale was wrong for most of the simulations, the trend of each plot is still going to be the same with the right scale;
The final design might still be optimal, more simulations need to be run to confirm it
Use Maxwellian angular distribution for the plasma source type instead and check if the optimal design is still the same.