1. The report of CEPC 650MHz Coupler in 2016
Ma Q. Huang T.M. Gu K.X. Bing F. Meng F.B. ...

2. Index The parameter of coupler; The CW input coupler status;
Rough project and time node;
RF window design;
Variable coupler idea.
The thermal calculated of coupler port.
Write the coupler section of "CEPC CDR status report"

3. The parameter of Coupler
Frequency
650MHz
Power
Oper: 300kW, CW
2 K heat load
0.6W ?(Temporary CW
(the whole 6 cavity module is 5W)
5 K heat load ?
80 K heat load Qe
variable / Fix coupling
Diagnostic
sufficient for safe operation and monitoring;
clean cavity assembly for high gradients
windows
one warm window

4. The CW input coupler status
The form below show some CW coupler in the world；
The LHC, KEK-B, APT coupler were the main reference.

5. 项目名称
频率（MHz）
耦合器型式
耦合窗型式
最大功率（kW） 附注
LEP2
400
coax
fix coupling
cylinder window
Test：565
Operating：100
TW Test
Operating bummer：288
LHC
variable coupling
Test：500
300
SW Test Operating number：16
HERA
500
Test：300
Operating：65
Operating bummer：16
CESR
（束流Test）
waveguide
waveguide windows
3-circular plate
Test：250
125
Operating：155
SW Test
Beam Test
circular plate
Test：450
Operating：300
360
Operating number 4
Max forward power
TRISTAN
509
coax plate
Test：200 70
Operating number 32
KEKB
Test：800
Operating：380
驻波Test
Operating number 8
APT
700
2-coax plate
Test：1000
850
JLAB FEL
1500
non-circular plate
Test：50
Operating：35
Operating number 2
BNL ERL gun
704
Design：500
Test：125
TW Test，2011
CEPC
650
coax plate/cylinder
Operating target：300
Operating power in the front rank

6. LEP2 & LHC coupler
LHC variable coupler- sperial adjust design

7. KEK-B & BNL ERL coupler TRISTAN/KEK-B & BNL ERL gun
Used in BEPC2; Fabricated the spare coupler in IHEP.

8. APT coupler
APT coupler
Max test power and variable coupling

9. The rough project (08/16-03/18)

10. The Time node Time node: Freeze the perameter and connector:2016-9
The max power & Qe were freezed in ;
The connector not freezed.
RF design: finished in
unfinished, will finished in
mechanical design: finished in
Design was ongoing.
making coupler: finished in
high power test: finished in (depends on the power sourse)

11. RF window design
The S11 of window is The RF transfer performance of whole coupler will be raised with waveguide-coax transfer.
The RF design will be changed and re-calculated after the mechanical design.
Design by Gu K.X.

12. Variable coupler idea
The form below show the operate mode and the QL. The range of the QL was 2.5E4~4.3E5；
Because the wide range of QL, the variable coupler was considerd.
Some model were made for it.
Z-HL mode hasn't considerd, because the power is too huge.
operate mode
H-HV
H-LP
H-HL W
Z-LL
Z-HL
Beam power（MW ） 33 50
18.3
0.84
cavity number
384
240
128 16 64
coupler power（kW ）
173
277
263
295
117
1757
QL（E5） 24 15
6.3
4.3 25
0.21

13. Some model for variable coupling
Add bellow on inner conductor;
too complex for manufacture and assembling.
Add bellow on out conductor;
easier than the 1st design;
It was selected for base model.
LHC coupler;
Maybe it was the further reseach design.

14. The thermal calculated of coupler port
The power loss on the out conductor will lead the quench on the coupler port;
Gu K.X. calculated the thermal loss on the out conductor with thermal anchor CW). The max temperature of the coupler port is 4~6K.

15. The thermal calculated of coupler port
Consider the tolerance of calculate and fabrication, It's better to add the cooling on the coupler port.
coupler port with cooling: KEK-B, LEP-2, LHC ;
coupler port without cooling: SNS, BNL-ERL, KEK-ERL;
The difference of He-gas cooling out conductor and thermal anchor cooling out conductor need further calculate.
The power loss on seal gap need to be confirmed(BNL-ERL use special seal gasket).

16. END

17. 耦合器束管温度的计算 边界条件： 动态热功率及漏热： 外导体上端298K，热锚固定80K&5K，束管右端固定2K； 通过功率300kW；
同一模型HFSS计算结果为：31.73 W，其中外导体粗段11.94 W，变径段15.63 W，细段4.16 W。
漏热估计：
2K 漏热
5K 漏热
80 K漏热
常温法兰 合计
动态漏热
1.22
6.11
18.88
6.54
32.75
静态漏热
0.070
1.544
4.781
-6.395