Recent Progress of FPCs at IHEP

68
[email protected] [email protected] 3 rd WWFPC Mini-workshop June 27-28, 2017, CERN, Switzerland 1 Recent Progress of FPCs at IHEP RF Group (IHEP) Tongming Huang, Weimin Pan, Qiang Ma, Haiying Lin, Kuixiang Gu [email protected]

Transcript of Recent Progress of FPCs at IHEP

Page 1: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 1

Recent Progress of FPCs

at IHEP

RF Group (IHEP)

Tongming Huang, Weimin Pan, Qiang Ma,

Haiying Lin, Kuixiang Gu

[email protected]

Page 2: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

General

• In the past one year, several kinds of power couplers

have been developed at IHEP for different projects.

2

Facility Cavity type Freq. Coupler type Power Status

C-ADSSpoke (SCC)

Β=0.21325MHz

Coax, fixed, capacitive

single window

Test: CW, 20kW (SW)

Oper: CW, 6 kW (SW)

Beam

commissioning

C-ADS5-cell (SCC)

β=0.82650MHz

Coax, fixed, capacitive

single windowTest: CW, 150 kW (TW)

High power

test

C-ADS RFQ (NC) 325MHzCoax, fixed, inductive

single windowOper: CW,70 kW

Beam

commissioning

HEPS-

TFQWR(SCC ) 166.6MHz

Coax, fixed, capacitive

single window

Requirements: CW,

200kW (TW)

Fabrication

completed

CEPC 2-CELL (SCC ) 650MHz

Coax, variable,

capacitive single

window

Requirements: CW,

300kW (TW)During design

CEPC 9-CELL (SCC ) 1300MHz

Coax, variable,

capacitive double

windows

Requirements: CW,

30kW (TW)During design

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 3: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 3

CONTENTS

• FPCs process for CADS project

• FPCs process for HEPS-TF project

• FPCs preliminary design for CEPC project

• Test station construction process for PAPS

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 4: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 4

ECR LEBT RFQ162.5MHz

CM1 (6 HWR010

SCCs)162.5MHz

MEBT1 CM3 (6 HWR015

SCCs)162.5MHz

CM2 (6 HWR010

SCCs)162.5MHz

ECR LEBTRFQ

325.0MHz

CM1 (7 Spoke012

SCCs)325.0MHz

MEBT1

CM2 (7 Spoke012

SCCs)325.0MHz

CM4 (6 Spoke021

SCCs)325.0MHz

35keV 2.1MeV 5.0 MeVMEBT2 10MeV

Phase-I 25 MeV

35keV 3.2MeV 5.0 MeV

Injector-II

Injector-I

FPC for C-ADS Spoke021 SCC• On June 5th 2017,this machine achieved 25 MeV with pulse current

of 12.6mA and CW current of 200uA (CW operation limited by huge

radiation dose).

• The improved FPCs of Spoke021 SCCs for CM4 indicated excellent

performance: fast conditioning, good vacuum.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 5: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Modification-1• The part highlighted by red diagram is inside the envelope of the cryo-module

to assure a clean assembly (assembled with cavity in class 10 clean room);

• Based on our experience, it’s very important to maintain the cavity

performance.

Water in

Water out

CM4 FPC assemble with cavity

in class 10 clean room

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 5

Page 6: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 6

Modification-2• The position of the coupler changed from upside to downside of the cavity,

which helps reducing the potential contamination of the cavity.

On-site CM4TCM CM4

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 7: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 7

Modification-3• Add the ultrasonic cleaning before the ultra pure water rinsing, which pays

great contribution to reducing the conditioning time.

• The ultrasonic cleaning procedure is referred to the recipe for TTF Coupler.

Ultrasonic cleaning procedure

of TTF coupler

Preprocessing before test

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 8: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Conditioning time comparison

83rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

• Before cavity cooling down, FPCs were conditioned;

• The conditioning time was reduced continuously, which benefited from

the modifications.

FPCs for CM1 FPCs for CM2 FPCs for CM4

Ultra sonic clean No Yes Yes

Position arranged on cavity Upside Upside Downside

Assembly with cavity in

class 10 clean room

No Yes Yes

Page 9: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

FPC for C-ADS 5-cell elliptical SCC

9

LEBT MEBT1RFQ

162.5MHzECR

SC-HWR

SC-CH

162.5MHz

LEBT MEBT1RFQ

325.0MHzECR

Spoke

325MHz

Spoke021

325MHz

28 cavities

Spoke040

325MHz

72 cavities

Elliptical 063

650MHz

28 cavities

Elliptical 082

650 MHz

85 cavities

Injector II

Injector I

MEBT2 10MeV

34 MeV 178 MeV 367 MeV 1500 MeV

2.1 MeV

3.2 MeV

35 keV

35 keV

TargetHEBT

650MHz 5-cell SCC

• 5-cell elliptical cavities are chosen for the main linac of

CADS in the medium energy section.

• FPC Challenges: • High power requirements: CW, 150kW

• Class 10 clean room assembly with cavity;

• Low heat load.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 10: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Cooling design based on thermal analysis

Components PartsRF

Loss (W)

Total

(W)

Window-IC

ceramic 55.3

156.2IC 87.1

OC 13.8

Coaxial-air

Teflon support 37.4

99.1 IC 42.5

OC 19.2

DoorknobDoorknob bowl 20.2

77.4 WG 57.2

Helium gas

cooling

Water cooling

Air cooling

The power dissipation @ 150kW,TW

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 10

Page 11: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Window thermal analysis

Temperature @ TW,CW,300kW Thermal stress @ TW,CW,300kW

• The maximum temperature is below 50℃• The maximum stress is 57MPa, far

below the flexural strength of ceramic

(~300MPa)

Temperature @ TW,CW,150kW

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 11

Page 12: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Copper coating VS RF dissipation

• In room temperature, 3 times skin depth of copper coating is enough to reduce the

RF dissipation usually;

• In cryogenic temperature, the thickness of copper coating can be reduced;

• As RRR increasing, the thickness of copper coating can be also reduced,

especially in low temperature.

RRR10 RRR30 RRR100

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 12

Page 13: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

The copper coating VS thermal conducting

• RRR ↑ thermal conducting ability ↑

• The thickness of the copper coating with high RRR should be smaller than that of with low RRR.

RRR10 RRR30 RRR100

1 1 2 2 1 1 2

d+ ( + )

D

Q T T TA A A

t x x x

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 13

Page 14: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Equivalent evaluation value for heat loss

cold

net hot clod

TQCOP FOM FOM

W T T

5 5

2 5 80 2 5 80

2 80

3.5 0.036K K

anchor K K K K K K

K K

COP COPQ Q Q Q Q Q Q

COP COP

Thermal

anchor cooling

Temperatures 2 K 5 K 80 K

COP 0.101% 3.57 % 10 %

Refrigeration power per

unit cryogenic heat load990 W 280 W 10 W

2 flow3.5 0.1helium KQ Q Q Helium gas

Cooling(5K 1 mg/s helium gas equal to 0.1W 5K heat loss)

The real refrigerator efficiency:

𝑊𝑛𝑒𝑡-the required refrigeration power;

Q- cryogenic heat load;

FOM: the technical refrigerator efficiency

143rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 15: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat loss calculation—thermal anchor cooling

Equivalent heat lossThe thickness of the copper coating

1 skin depth 2 skin depths 3 skin depths

RRR10 5.386 W 5.184 W 5.163 W

RRR30 4.198 W 4.343 W 4.454 W

RRR100 3.728 W 3.991 W 4.385 W

• Given the same thickness of copper coating, the heat loss decreased as RRR increasing

• When the RRR is 10 (in our case), 2 times skin depth copper coating is recommended

• As the RRR higher than 10, the optimum thickness of copper coating can be smaller

than 2 times skin depth

Simulation model

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 15

Page 16: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat loss calculation—helium gas cooling

Cooling way RRR10 RRR30 RRR100

2K Equivalent 2K Equivalent 2 K Equivalent

Helium gas 0.452 W 4.582 W 0.297 W 4.040 W 0.231 W 3.810 W

Thermal anchor 0.387 W 5.184 W 0.267 W 4.343 W 0.212 W 3.991 W

Heat loss comparison

163rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

• Comments: How to

decide the cooling of

outer conductor?

• Heat loss

• Quench?

Page 17: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

The fabrication of the coupler

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 17

Page 18: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

S11 measurement

• No WR1500-N type adapter, only WR1800-N is available

• The mismatching was gated during the measurement;

• Test results: S11= -17.80 dB, S21= -0.21 dBWR1800-N type adapter

S11 measure setup: WR1500-

WR1800-N type adapter

WR1800-N adapter mismatched at 650MHz

183rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 19: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

High power test-1

Conditioning historyTest bench

• CW + Pulse conditioning processed alternately.

• After 30 hours conditioning, reached to

150kW,CW

• Vacuum and temperature performance is

normal: window temperature increasing is

below 5 ℃

Power VS vacuum after

conditioning

After conditioning, no hard MP

below 150kW, agree well with

the simulation.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 19

Page 20: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 20

High power test-2

Without permanent magnet

Permanent magnets

With permanent magnet

• Green: Pf

• Yellow: Pr

• Red: upstream FPC

vacuum

• Blue: downstream

FPC vacuum

• Permanent magnets proved effective to suppress MP.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 21: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

FPC for C-ADS 325MHz RFQ

• Coupling loop:

– Structure improvement:

larger size, more smooth;

– TiN coating;

• Pumping port:

– φ63mm instead of φ35mm

for better vacuum pumping

• The RF contact ring

between the coupler and

the cavity was canceled:

– RF contacted by the copper

gasket;

– Avoided the ring burning

successfully.

old new

RF contact ring was

canceled.

TiN

coating

area

• The FPC for C-ADS 325MHz RFQ is improved based on

the operation experiences.

• The main modifications are as follows:

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 21

Page 22: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 22

Clean assemblyAfter assembly

Before baking After assembled in tunnel

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 23: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

High power conditioning• Four FPCs were conditioned with the cavity together.

• The experiences learned from the conditioning:

– The couplers are the main barriers during the low power and low duty factor

(DF) conditioning.

– The coupler outgassing is related with the shifter position, i.e. each coupler

may outgassing alternately as the shifter moved.

– The cavity on/off resonance status plays a big role in the coupler outgassing.

Keeping a good resonance can avoid antinode wave move and reduce the

coupler outgassing;Cavity frequency controlling is very important to

increase conditioning efficiency.

– As duty factor increasing, the cavity discharging happened more frequently

It’s quite necessary and important to build a reflection power-based

discharging protection system.

– As duty factor increasing, the cavity cooling water temperature became

unstable, which resulted in cavity off resonance and coupler outgassing

seriously. Increase the cooling water temperature stability is urgent.

– Once power off lasting for more than 1 hour, the conditioning process will

back up a little. Keep continuous conditioning is necessary.

• Finally, RF power reached up to CW, 270kW.

233rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 24: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

20161024d vacuum (50Hz/9.4%

1%, Pf 300kW)

Main

outgassing:

2#,3# FPCPhase

shift

Main

outgassing:

4# FPC

blue:1# FPC; red: 2# FPC

green:3#FPC; black:4#FPC

purple:cavity west;orange:cavity east

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 24

The coupler outgassing is related with the

shifter position, i.e. each coupler may

outgassing alternately as the shifter moved.

Page 25: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

20161026d vacuum (50Hz/15.2%, Pf 300kW)

Main outgassing:

4# FPC

Magnet arranged on

the 4# FPC window

4# FPC

outgassing

suppressed

blue:1# FPC; red: 2# FPC

green:3#FPC; black:4#FPC

purple:cavity west;orange:cavity east

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 25

Permanent magnets proved effective to suppress MP.

Page 26: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

20161026n vacuum (50Hz/20%, Pf 300kW)

Water temperature

unstable resulted in cavity

off resonance and coupler

outgassing seriously

blue:1# FPC; red: 2# FPC

green:3#FPC; black:4#FPC

purple:cavity west;orange:cavity east

263rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

The cavity on/off resonance status plays a

big role in the coupler outgassing.

Page 27: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

The calculated displacement of the wave antinode inside the

coupler as frequency shift

△f(KHz) △φ(°) △Z(mm)0 0 0.0

1 8 20.5

2 16 40.5

3 23 59.6

4 30 77.5

5 37 94.0

6 43 109.2

7 48 123.1

8 53 135.7

9 57 147.2

10 62 157.7

20.5 90 230.8

• As can be seen, the displacement of the wave antinode is very big when the

frequency shift happened close to the cavity resonant frequency.

• As far away from the resonant frequency, the frequency shift resulted

displacement of the wave antinode become smaller.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 27

Page 28: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 28

CONTENTS

• FPCs process for CADS project

• FPC process for HEPS-TF project

• FPCs preliminary design for CEPC project

• Test station construction process for PAPS

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 29: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 29

FPC for HEPS-TF 166.6MHz SCC

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 30: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 30

Parameter Value

Frequency 166.6 MHz

RF power CW, 200kW

External Q 3.78E4

Impedance of coaxial line 50 Ohms

Ceramic type coaxial, planar

Cooling type Window & inner conductor: water cooling;

Outer conductor: helium gas cooling

Reflection coefficient S11< –20dB

Bandwidth: ~25MHz

Vacuum Vacuum pressure: 1E-7 Torr

Leak rate: 1 E-9 mbar·ℓ / sec

Requirements• Challenges:

• High power level: CW, 200kW

• Clean assembly

• Potential window damage from cavity FE

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 31: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Analysis on window damage of FE • A lesson learned from the in-

cryomodule RF processing of the

Spoke SCC for C-ADS project is

that, cavity FE may resulted in fatal

ceramic damage, especially for the

low beta SCC with coupler located

in the cavity wall with strong

transvers electric field, instead of

beam pipe.

• In our case, the power coupler just

located in the cavity outer cylinder

wall, where exists transverse

electric-field; and the window

damage due to cavity FE is possible.

So it’s necessary to study the FE

effect on FPC window.

• In order to weaken the FE effect, the

FPC should be arranged at the area

without strong transvers E-field.

31

Simulation of FE electrons bombardment

on ceramic for Spoke SCC of C-ADS

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 32: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

• Stay far from high transvers electric field region to suppress electron

bombardment on the ceramic window.

• The trajectory of the FE electrons facing the coupler port are simulated for

different accelerating gradients, phases and different coupler positions.

32

Analysis on window damage of FE-2

Pos_FPC

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 33: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

• The analysis shows that:

– The FE induced electrons can fly into the FPC through the coupler port when the phase

above 90 degree; however, they can’t arrive at the ceramic surface since the strong

magnetic field acting on them to cause bending.

– The FE effect can be neglected when the Pos_FPC chosen as 160mm and the ceramic

arranged far from the coupler port.

33

Analysis on window damage of FE-3

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 34: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Air in

Air out

34

Cooling design• To meet the high power capability, cooling are designed based on

careful thermal analysis.

Inner T-box temperature @200kW,CW,TW

Window thermal stress@200kW,CW,TW

△T:10K

39MPa

• Cooling scheme:• T-box: air cooling

• Inner Window: water cooling

• Inner conductor of vacuum

part: water cooling

• Outer conductor of vacuum

part: helium gas cooling

Air in Air in

Water in Water out

He gas inHe gas out

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 35: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Fabrication and high power test

35

• The fabrications of two prototypes and the test bench have been

finished recently.

• The high power test will be processed in July. CERN conditioning loop

will be applied in the test. Appreciate the great help.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 36: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 36

CONTENTS

• FPCs process for CADS project

• FPC process for HEPS-TF project

• FPCs preliminary design for CEPC project

• Test station construction process for PAPS

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 37: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

CEPC coupler specification and challenges

Requirements Main ring Booster

Frequency (GHz) 0.65 1.3

Power (kW) 300 10

Coupling (Qext) Variable: 1E5~2E6 Variable: 4E6~4E7

2 K heat load

(dynamic300kW,TW,CW)1 W 0.3 W

AssemblyClean assembly of coupler to

cavity in class 10 clean room

Clean assembly of coupler to

cavity in class 10 clean room

Challenges of main ring FPC:• High power handling capability:CW, 300kW (400kW, update);

• Variable coupling: wide range Qext adjusting;

• Clean assembled with cavity in class 10 clean room: very compact

design of vacuum part;

• Low heat load control is very difficult.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 37

Page 38: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

How to realize a variable Qext?• Theoretically, there are two Qext adjusting schemes for coaxial, probe type

FPC:

– Variable Qext FPC :Changing the penetration depth of the antenna tip by

compressing or stretching the outer conductor or inner conductor. In this case,

the Qext is adjusted directly. Usually, bellow structure should be adopted to

realizing the above changing. (Universal method)

– Three-stub tuner: Realizing impedance transforming by adding an three-stub

tuner. In this case, Qext is adjusted indirectly, i.e. the Qext of the FPC-cavity

coupling port is still fixed; and the Qext of the three-stub tuner-FPC-cavity has

been adjusted to make the power source see a matched load.

38

Variable Qext FPC Three-stub tuner

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 39: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Qext adjusting by Three-stub tuner-Application

Three-stub tuner was used for

Qext adjusting from 2E7 to 8.5E6

for a 704 MHz 5-cell cavity at BNL

• My opinion: Qext adjusting by three-stub isn’t a common method, which

usually adopted as small Qext (<1 order) adjusting is required for a

updated machine. I.E. it’s a passive method of Qext adjusting due to a

unmodifiable FPC and cryo-module.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 39

Page 40: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Qext adjusting method Pros Cons

Variable Qext FPC

• Safe operation condition

for FPC: TW

• Qext adjust range is

larger: > 2 orders

• Qet adjust direction:

both increase and

decrease

• Complicated FPC design;

• Higher cost of FPC

Three-stub tuner + fixed

Qext FPC

• Simple FPC design

• Lower cost of FPC

• Bad operation condition for

FPC: MW or SW

• Qext adjust range is smaller:

<1 order

• Qext adjust direction: only

increase

• Our decision: • Baseline: variable Qext FPC for safe operation of FPC

• Backup: three-stub tuner + fixed Qext FPC

Comparison Comments?

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 40

Page 41: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Typical variable Qext FPC

41

Change the outer conductor length

Change the inner conductor length

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 42: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

FPC for the main ring

42

• The preliminary design of the FPC for the main ring are under going.

• Up to now, two versions of design are considered, differ in the Qext

adjusting scheme.

Version 1: changed the outer conductor length Version 2: change the inner conductor length

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 43: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

D

h

Φ

Qext calculation model

pi-mode E-field

Qext varied with the Coax antenna penetration depth

• Based on the simulation, a length about 30mm is required

• Considering the bellow compressing and stretching strength, the bellow

length is chosen 90mm (3 times)

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 43

Page 44: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Preliminary comparison of two versions design

44

Pros Cons

Version 1

(bellow located in

outer conductor)

• Simple inner

conductor (IC)

design

• No potential

discharging and

over heating

problem on IC

• Complicated outer conductor

(OC) design

• The bellow should be cooled

by water due to high power

• Too short distance between

room and cryogenic

temperature large heat

load

Version 2

(bellow located in

inner conductor)

• Simple and easy

OC design

• Easy to control the

heat load

• Complicated IC design

• Potential discharging and

over heating problem on IC

• The thermal analysis including thermal-stress and heat load for version 1

has been done, and will be done for version 2.

• Then, the final decision will be done after that.

• Any suggestions about the design?

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 45: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat load analysis of version 1

• Since the very high power level of the main ring FPC, the thermal design aiming at a low heat load is very important;

• The preliminary analysis shows that:

– RF shielding of the gap between the coupler and cavity connecting flange is very important, since which made great contributions to the 2K heat load.

– Water or helium gas cooling of the outer bellow is must.

The heat load calculation model

300K

80K

5K

2K

Nb+ Nb-Ti flange

SS flange

1mm Stainless

steel + 10um

copper coating

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 45

Page 46: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat load analyzed for different situations

(Version 1)

• The heating effect of the gap between coupler and cavity connecting flanges is calculated;

• The temperature distribution, as 300kW (CW) RF power passing through, is also calculated.

• With ‘gap’:– Bellow cooled by 80K thermal

anchor

– Bellow cooled by water

• Without ‘gap’ and bellow cooled by water, the position of the 5K thermal anchor is optimized.

The gap (0.4mm*4mm) between

coupler and cavity connecting flanges

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 46

Page 47: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat load calculation-1 @300kW,CW,TW

The maximum temperature is 820K that locating

around the bellow when the bellow cooled by

only 80K thermal anchor.

2 K heat load -2.56 W

5 K heat load -11.5 W

80 K heat load -27.9 W

300 K heat load -26.8 W

Component Power dissipation

Stainless steel of gap 2.28 W

Al-Mg alloy sealing gasket 0.03 W

Outer conductor of FPC 66.5 W

• The bellow is over heating when only cooled by 80K thermal anchor.

Conclusion1: Water cooling of the

outer bellow is must.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 47

Page 48: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat load calculation-2 @300kW,CW,TW

The maximum temperature is 301.7K and 2K heat load is 2.74W when the

bellow cooled by water and 0.4mm gap existing between the coupler and

cavity connecting area ; the maximum temperature locating around the Nb-Ti

flange is 4.6K (<Hc, no quench).

2 K heat load -2.74 W

5 K heat load -8.94 W

80 K heat load -30.32 W

300 K heat load -0.16W

Component Power dissipation

Stainless steel of gap 2.28 W

Al-Mg alloy sealing gasket 0.02 W

Outer conductor of FPC 48.4 W

• The bellow cooled by water (25 ℃).

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 48

Page 49: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Heat load calculation-3 @300kW,CW,TW

The maximum temperature is 302.2K and 2K heat load below 1W when the

bellow cooled by water and no gap between the coupler and cavity connecting

area ; the maximum temperature locating around the Nb-Ti flange is 3.17K (<Hc,

no quench).

No gap With gap

2 K heat load -0.99 W -2.74 W

5 K heat load -8.17 W -8.94 W

80 K heat load -30.68 W -30.32 W

300 K heat load -8.09 W -0.16W

• When there is no gap between the coupler and cavity connecting area, the 2K heat load

will be reduced greatly.

Conclusion2: RF shielding of the gap

between the coupler and cavity

connecting flange is very important.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 49

Page 50: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Further thermal analysis of version 1• IC of vacuum part:300K water cooling (convection: 1500)

• Outer bellow of vacuum part:300K water cooling (convection: 1500)

• Air side:300K air cooling (convection: 50)

2K

5K80K

300K

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 50

Page 51: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Temperature @ 400kW,CW

51

Ceramic

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 52: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 52

Thermal stress @ 400kW,CW• Boundary:

• RF heat load

• Atmosphere pressure

• Frictionless support

Window

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 53: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Issues about the version 2 design

• Potential risks:

– Over heating of the bellow due to horizontal arrangement of

coupler

– Potential discharging around the bellow area

– The corrosion of the bellow from the cooling water

• What’s the best choice of material for the bellow?

– Be-Cu

– Copper plating +SS

– ?

• Cooling method of IC

– Water cooling

– Air cooling

– Will be decided based on thermal analysis

533rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 54: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Cold part Warm partWarm window

& doorknobCold window

RF model of CEPC booster cavity FPC Optimized power transmission performance

• RF geometry optimization aiming at impedance matching

The FPC of booster-RF design

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 54

Page 55: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 55

The FPC of booster-thermal analysis

@ CW, 20kW,TW

• The temperature distribution as 20kW CW RF passing through is

simulated.

2K 5K 80K

Dynamic at 20kW, TW (W) 0.23 2.4 57

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 56: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

The FPC of booster-thermal stress analysis

56

• The thermal-stress of warm and cold windows as 20kW CW RF

passing through is simulated.

• Problem: Too large thermal stress of cold window due to too

large temperature gradient. How to solve?

Warm window

Cold window3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

420MPa: too large

Page 57: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

2K5K5K80K80K300KWater inWater out

Gas in

Gas out

57

The FPC of booster-cooling scheme

• The cooling design is based on the thermal analysis

• The mechanical design has been finished; and the

prototypes fabrication will be started soon.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 58: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 58

CONTENTS

• FPCs process for CADS project

• FPC process for HEPS-TF project

• FPCs preliminary design for CEPC project

• Test station construction process for PAPS

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 59: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

PAPS project overview

• “Platform of Advanced Photon Source

Technology R&D”, to provide infrastructure

for construction of future project.

• Budget: 500M CNY funded by Beijing Gov.

• Construction: 2017.5-2020.6

• Consist of 7 systems:

RF system

Cryogenic system

Magnet technology

Beam test

X-ray optics

X-ray detection

X-ray application

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 59

Page 60: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

PAPS-RF system• The PAPS-RF system has two targets :

– Build a SRF facility

– Conduct R&D on cavities and ancillaries

• The SRF facility is biased on mass production for SRF projects– Post-processing, clean assembly, VT/HT/conditioning of cavities,

couplers, and cryomodules.

– Compatible of 166MHz, 325MHz, 500MHz, 650MHz, and 1.3GHz

– 200-400 cavities (couplers) per year

– ~20 cryomodules per year

– Support R&D on new material

and new technology

– Total area of 4500 m2

• Cryogenic system:

300W @ 2K

PAPS-RF

TestingC

avity VT

Cavity H

T

CM

con

ditio

nin

g

Co

up

ler co

nd

ition

ing

Clean assembly Labs

Post p

rocessin

g

Micro

wave &

LLR

F

SC m

aterials

Cavity R

&D

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 60

Page 61: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

• A large-scale high power test stand

for power couplers, covering four

frequencies of 166.6MHz,

500MHz, 650MHz and 1300MHz,

focusing on the future accelerator

projects, such as HEPS, CEPC and

so on, is to be built in two years.

• Function and highlights:– Pre-processing: cleaning, baking

– Clean assembly and disassembly

– Test 6~8 couplers per week

– The conditioning processed in a

large class 10000 clean room

more cleaner

Frequency Test power

166.6 MHz 50 kW, CW

500 MHz 100 kW, CW

650 MHz 150 kW, CW

1300 MHz 15 kW, CW

Goal of Power Coupler Test stand

The power capability of

coupler test stand

3

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 61

Page 62: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

3

General Layout of Coupler Test Stand

• The coupler test stand consists of three zones : 1) One class 10 room for

assembly; 2) One class 10000 room for conditioning; 3) One normal hall for

reception, buffer storage and LLRF control.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 62

Page 63: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

Coupler life cycle

① Component Reception

② Component Leak check

③ Component Storage

④ Cleaning Processing

⑤ Clean assembly

⑥ Assembly leak check

⑦ Baking

⑧ Conditioning

⑨ Dismounting and packing

⑩ Delivery

N2 cabinet

W1.5*D0.8*H2

14m

8m

Air shower

(L1.5*W1.25)

Dressing room

(L4*W2.05)

Sto

rag

e ca

bin

etAssembly table

(W2*D0.8*H0.8)

Sh

elf

W2*D

0.6

*H

1.8

Ass

emb

ly t

ab

le

(W2*D

0.8

*H

0.8

)

Sh

elf

W2*

D0.6

*H

1.8N2 cabinet

W1.5*D0.8*H2Ultra pure water

rinsing bath --Ultra sonic clean bath

(W2*D0.8*H1)

9-3/16" Coaxial Line

166.6MHz test bench

Shelf

W2*D0.6*H1.8

Shelf

W2*D0.6*H1.8

1.3

GH

z t

est

sta

nd

1.3

GH

z t

est

sta

nd

WR650 WG

650MHz

test

bench

500MHz

test

bench

WR1500

WG

WR1500

WG

10m

Baking

oven

W2*D1.5*H2

Baking

pump

chiller

N2 c

abin

et

W1.5

*D

0.8

*H

2

N2 cabinet

W1.5*D0.8*H2

Cavity baking

ovencontrol cabinet

Assembly table

(W1.6*D0.8*H0.75)

LLRF Control area

(L7*W2)

④①

③⑤ ⑥

⑦ ⑧

Hall

Class10000

Class10

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 63

Page 64: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

• Four high power test

systems

(166.6/500/650/1300MHz)

will be built, which

including:

– Power sources

– Test benches

– LLRF control systems

– Cooling systems

– Power transferring systems:

WG, circulator, variable

short circuit, dummy load

System Diagram of Coupler Test stand

High power test system diagram

LLRF for power measurement

Pre-AMP Circulator

Connected waveguide

Vacuum

system

+44dB40W

+40dB250KW

Klystron

-50dB

Water terminating load

RF power source

Downstream

coupler

Upstream

coupler

Pin Pr

Pkly

Vacuum

gaugeArc sensor

LLRF for

Interlock

PrPin

Water terminating load

Variable short circuit

Cooling

systemRF shift

Oscillator

Test bench

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 64

Page 65: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

• For the room temperature

high power test, two

couplers are assembled

back to back in a test

bench usually.

• Test benches:

– Waveguide box: high

frequency (>500MHz)

– Resonant cavity: low

frequency (<400 MHz)

• low-beta cavity (HWR, QWR);

• approximate capacitor-loaded

coaxial cavity

• Different kinds of test benches

covering four frequencies will

be developed.

Test Benches of Coupler Test Stand

650 MHz test bench

166.6 MHz test bench

1300MHz test bench

500MHz test bench

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 65

Page 66: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

4

Other Infrastructures of Coupler Test Stand

166.6 MHz 500 MHz 650 MHz# 1300 MHz*

Power source Solid state power source,

50kW, CW

Solid state

power source,

100kW, CW

Solid state

power source,

150kW, CW

Solid state power

source, 15kW, CW

Wave guide Coaxial, 9-3/16” WR1500 WG WR1500 WG WR650 WG

Variable short circuit 1) Variable range: half wave length; 2) satisfy the power requirements of each

frequency.

Dummy load 50kW, CW 100kW, CW 150kW, CW 15kW, CW

LLRF Control 1) Auto conditioning; 2) Safe interlock; 3) Data acquiring and analysis

Cooling system Water cooling;

Air cooling

Water cooling;

Air cooling

Water cooling;

Air cooling

Air cooling

#: The power is scheduled to increase to 300 kW, CW in the near future;

*: The power is planned to increase to 30 kW, CW in the future.

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland 66

Page 67: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn

• In the past one year, several kinds of power couplers

have been developed:

– 6 couplers of Spoke021 SCC for CADS project have been designed,

fabricated and tested; then joined the beam commissioning

successfully.

– One prototype of 650MHz 5-cell SCC for CADS project has been

designed, fabricated and tested up to CW 150kW.

– 4 improved version couplers of 325MHz RFQ for CADS project

have been conditioned together with RFQ cavity, and reached to

CW 270kW.

– Two prototypes of 166.6MHz QWR SCC for HEPS-TF project have

been design, fabricated; and will be tested in July 2017.

– FPCs of CEPC SCCs for both main ring and booster are under

design. Big challenge is encountered, especially for the main ring

SCC

– A large-scale high power test stand is to be build in two years; and

the CDR is preparing now.67

Summary

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland

Page 68: Recent Progress of FPCs at IHEP

[email protected]@ihep.ac.cn 68

Thank you for your attention !

Thanks for the helps!

Welcome Collaboration!

3rd WWFPC Mini-workshop

June 27-28, 2017, CERN, Switzerland