1. CEPC 650MHz Klystron Development
Zusheng ZHOU(周祖圣)
Accelerator Division
Jun.21, 2016

2. Content Design Proposal R&D Progress Summary Electron gun
RF interaction region
Focusing magnet
Output window
Collector
Beam tester
Summary

3. Klystron key design parameters Centre frequency (MHz)
Design proposal
Klystron key design parameters
Parameters mode
Now
Future
Centre frequency (MHz)
650+/-0.5
Output power (kW)
800
Beam voltage (kV) 80 70
Beam current (A) 16 15
Efficiency (%) 65

4. Short-term schedule

5. Klystron Schedule and strategy
Because of klystron efficiency is more than 80%, in order to fulfill this program, there may have following problems:
we (China) have not an experienced to manufacture the high power, UHF klystrons. There is not the big furnace infrastructure in China also.
Design and simulation are not enough and matured, therefore we need to step up one by one.
Let’s start from beam tester, classical design and high efficiency design.
In order to save the money and time, demountable structure is another way.

6. Klystron Schedule and strategy(2)
Merits
Saving the money
Saving the time
Possible to try 2 or 3 designs
(1) Beam tester
(2) #1 prototype
(3) #2 prototype

7. R&D Progress Electron gun RF interaction region Focusing magnet
Output window
Collector
Beam tester

8. Electron Gun DGUN EGUN R=0, Z=0 (with f10 hole)
Current=15.09 A
Perveance= 1.45μI/V3/2
R=0, Z=0 (5mm shifted MA &anode towards cathode part )
Current=15.19 A
Perveance= 1.46μI/V3/2
R=0, Z=0 (with f10 hole)
Current=14.83A
Perveance= 1.43μI/V3/2
R=0, Z=0
Current=15.09A
Perveance= 1.45μI/V3/2
1.7% difference
0.7% difference

9. Simulation Results using DGUN
Triode gun（anode modulated）with f10 hole
DGUN simulation result :
Beam Diameter=17.2mm
Current=15.09 A
Perveance= 1.45μI/V3/2

10. Simulation Results using EGUN
Triode gun（anode modulated）with f10 hole
EGUN simulation result :
Current=14.83A
Perveance= 1.43 μI/V3/2
Beam Diameter= 17.14mm

11. RF interaction region
1d simulation for classical design, efficiency is more than 75%.
1 d AJDISK simulation results

12. RF interaction region
5 Cavities(fundamental mode) and 1 2nd harmonic cavity
Simulation results give the cavities size.
Cavities size

13. Focusing magnet POSSION Simulation Results
Brilliouin field= 111 Guass by assuming B/Bb=1.8
then-> K=0.6 -> Bcathode=26.5 Gauss
Magnetic Field= 207 Gauss
POSSION Simulation Results
Amplitude of magnetic field Bz on axis

14. Focusing magnet
DGUN Simulation Results

15. Output window’s reflection coefficient vs. frequency
The output window is designed by coaxial choke structure
CST simulation results
Output window structure
Output window’s reflection coefficient vs. frequency

16. Collector
The maximum power for collector is about 1.23MW, water cooling flow is about 1400l/min.
Thermal deformation simulation
The mechanical design is completed, it’s ready for manufacture.

17. Beam tester
Beam Tester with Magnetic Field
Z (mm)
1500.0
1000.0
500.0
2000.0
2500.0 Bz
Solenoid
In order to cool the collector, applying the magnetic field is better.
4/12/2016

18. Beam tester Mechanical design
The mechanical design for beam tester is in progress, we hope it will be fabricated on next month.
4/12/2016

19. Summary Complete gun design; Order the cathode and ceramic;
Complete the collector design;
Complete the designing / drawing and start manufacturing
In order to do the quick manufacturing, parallel schedule for manufacturing and cathode manufacturing and processing.
Furnace problem
There is no big furnace in China, we are looking for appropriate company to build it.

20. Thanks for your attention!