1. Gabriel Palacios gabrielp@jlab.org 08/30/18
200 kV guns CST + GPT
Gabriel Palacios
08/30/18

2. Summary Models Field maps False color Surface fields Emittance
AVG_Z vs STD_Y
Beam monitors

3. Models: T-cathode

4. Models: Mushroom

5. Models: Small mushroom

6. Models: Sphere, 6cm gap, short anode

7. Models: Sphere, 9cm gap, long anode

8. Models: Sphere, 9cm gap, long anode

9. Cathode-anode gap:
The data for the following plots was taken along the cathode anode gap as a function of the height (on the photocathode surface) varying from -6mm to 6mm.

10. Transverse vertical field maps

11. CST results: Transverse electric field – T-shape
The gray data set is the whole field map. The different colors show how the transverse electric field changes as a function of height on the photocathode in the interval -6mm<y<6mm
119% difference between 0.21 and -0.04
Note: offset in x due to CST model photocathode not in 0,0 coordinates

12. CST results: Transverse electric field – Mushroom
The gray data set is the whole field map. The different colors show how the transverse electric field changes as a function of height on the photocathode in the interval -6mm<y<6mm
70% difference between 0.27 and 0.08
Note: offset in x due to CST model photocathode not in 0,0 coordinates

13. CST results: Transverse electric field – Small mushroom
The gray data set is the whole field map. The different colors show how the transverse electric field changes as a function of height on the photocathode in the interval -6mm<y<6mm
116% difference between 0.22 and -0.03
Note: offset in x due to CST model photocathode not in 0,0 coordinates

14. CST results: Transverse electric field – Sphere, 6 cm gap, short anode
The gray data set is the whole field map. The different colors show how the transverse electric field changes as a function of height on the photocathode in the interval -6mm<y<6mm
20% difference between 0.1 and 0.08
Note: offset in x due to CST model photocathode not in 0,0 coordinates

15. CST results: Transverse electric field – Sphere, 6 cm gap, long anode
The gray data set is the whole field map. The different colors show how the transverse electric field changes as a function of height on the photocathode in the interval -6mm<y<6mm
16% difference between 0.06 and 0.05
Note: offset in x due to CST model photocathode not in 0,0 coordinates

16. CST results: Transverse electric field – Sphere, 6 cm gap, long anode
The gray data set is the whole field map. The different colors show how the transverse electric field changes as a function of height on the photocathode in the interval -6mm<y<6mm
16% difference between 0.06 and 0.05
Note: offset in x due to CST model photocathode not in 0,0 coordinates

17. Comparing all models at the c-a gap only for the y=0 electric field line

18. CST results: Transverse electric field at C-a gap axis
All the data sets correspond to the center line in the cathode-anode gap. Different colors represent different shields.
~12% difference between 0.17 and 0.15
~53% difference between 0.17 and 0.08

19. CST results: Transverse electric field – No shield vs Original vs all shields at insulator interface
The potential and electric fields along the rubber plug – ceramic insulator interface was obtained (as shown in the image as a red dotted line), plotted as a function of the height (y- coordinate).

20. CST results: Transverse electric field –at insulator interface
Different colors represent different shields.
38% difference between 0.8 and 1.3
63% difference between 0.8 and 2.2

21. CST results: Potential –at insulator interface
Different colors represent different shields.
20% difference between 123 and 153

22. False color

23. CST results: Electric field norm– No shield
Triple points:
Upper flange:5MV/m
29MV/m at cusp
Triple points:
Cathode: 3.6MV/m
6.5MV/m
7.9MV/m
4.87 MV/m

24. CST results: Electric field norm– original shield
Triple points:
Upper flange:10MV/m
7.2MV/m
Triple points:
Cathode: 0.6MV/m
5.6MV/m
7.9MV/m
4.85 MV/m

25. CST results: Electric field norm– Shield 8
Triple points:
Upper flange:11MV/m
7.9MV/m
Triple points:
Cathode: 1.2MV/m
6.5MV/m
8.08MV/m
4.86 MV/m

26. CST results: Electric field norm– Sphere 6cm gap short anode
Triple points:
Upper flange:9.7MV/m
5.5MV/m
6.3MV/m
Triple points:
Cathode: 0.3MV/m
7.2MV/m
4.6 MV/m

27. CST results: Electric field norm– Sphere 6cm gap short anode
Triple points:
Upper flange:10MV/m
5.8MV/m
6.9MV/m
Triple points:
Cathode: 0.3MV/m
7.8MV/m
4.6 MV/m

28. CST results: Electric field norm– Sphere 6cm gap short anode
Triple points:
Upper flange:10MV/m
5.5MV/m
5.2MV/m
Triple points:
Cathode: 0.3MV/m
6.4MV/m
4.5 MV/m

29. Electric field norm: No shield vs Original vs shields 1 vs shields 2
On the metallic surface
Pics are sadly not to scale, in all of them the cathode size is the same.

30. CST results: Electric field norm– T-shape

31. CST results: Electric field norm– Mushroom

32. CST results: Electric field norm– Shield 8

33. CST results: Electric field norm– Sphere 6cm gap short anode

34. CST results: Electric field norm– Sphere 9cm gap long anode

35. CST results: Electric field norm– Sphere 6cm gap long anode

36. GPT stuff

39. Beam monitors

40. Fin.

41. CST frame of reference:y x z
X goes into the page.