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

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

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

Short-term schedule

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.

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

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

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

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

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

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

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

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

Focusing magnet DGUN Simulation Results

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

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.

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

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

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.

Thanks for your attention!