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[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]@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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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?
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The fabrication of the coupler
3rd WWFPC Mini-workshop
June 27-28, 2017, CERN, Switzerland 17
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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
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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.
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June 27-28, 2017, CERN, Switzerland 19
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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
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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
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Clean assemblyAfter assembly
Before baking After assembled in tunnel
3rd WWFPC Mini-workshop
June 27-28, 2017, CERN, Switzerland
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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
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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.
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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.
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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.
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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
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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
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FPC for HEPS-TF 166.6MHz SCC
3rd WWFPC Mini-workshop
June 27-28, 2017, CERN, Switzerland
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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
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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
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• 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
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• 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
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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
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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
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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
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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
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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
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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.
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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?
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June 27-28, 2017, CERN, Switzerland 40
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Typical variable Qext FPC
41
Change the outer conductor length
Change the inner conductor length
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June 27-28, 2017, CERN, Switzerland
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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
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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)
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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
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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
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June 27-28, 2017, CERN, Switzerland 45
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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
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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.
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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 ℃).
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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.
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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
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Temperature @ 400kW,CW
51
Ceramic
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Thermal stress @ 400kW,CW• Boundary:
• RF heat load
• Atmosphere pressure
• Frictionless support
Window
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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
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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
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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
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June 27-28, 2017, CERN, Switzerland
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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
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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.
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CONTENTS
• FPCs process for CADS project
• FPC process for HEPS-TF project
• FPCs preliminary design for CEPC project
• Test station construction process for PAPS
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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
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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
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• 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
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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.
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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
②
③⑤ ⑥
⑦ ⑧
⑨
⑩
Hall
Class10000
Class10
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• 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
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• 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
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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.
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• 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
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Thank you for your attention !
Thanks for the helps!
Welcome Collaboration!
3rd WWFPC Mini-workshop
June 27-28, 2017, CERN, Switzerland