The 20th KEKB Accelerator Review Committee (2015.02.23)

Status of RF System
T. Kobayashi from SKB RF Team1

Outline
1. Introduction

DR-CavARES

2. Normal Conducting Cavity• ARES Cavity• DR Cavity

SCC

3. Super-Conducting Cavity
4. High Power RF System (Kly, KPS, WG)
5. Low Level RF Control System
6. SummaryHigh Power RF Systems
KlystronKPS

LLRF

WG System

2

Intro.: RF System Arrangement (ultimate)1

Ce+: 8.0Gev x 1.4AHERe-: 3.5Gev x 1.8A

LER

2

B

KEKB)RF

OHO

D4

A

B

FUJI

D7

D5
2

1

C E

E

2

A

K. Akai

2

2

D

C

Beam Power/Cavity: ~200kW

B

A

B

C

Drive Power/cavity: ~350kW

SuperKEKB)RF,,(ul/mate)

add020more0klystrons,0HP&LL,00
add010more00power0supply

add020klystrons,0HP&LL0
add020power0supplies

add050klystrons,0HP&LL0
add030power0supplies0

2

D4

2

2

D7

D5

2

H G F E D C B A22

A B C D E F

F E

2

2

2

D

2

C

B

A

B

D

E

2

NIKKO
2

2

D C B A

D11
2

1

A B C D E F

Max. RF Power Config.

D8

2

A

1

2

2

A

D10

D8

C

D10
2

2

D E F

2

2

2

D C B A

D11
2

2

A B C D E F

e+: 7Gev x 2.6A
e-: 4Gev x 3.6A

add020SC0(opVon)0

add020ARES
remove040ARES

convert0to0LER

Beam Power/Cavity: ~600kW
Klystron,0HP&LLRF0system

Drive Power/cavity: ~750kW2

Type0“A”0power0supply0(for0two0klystrons)

1

Type0“B”0power0supply0(for0one0klystron)

ARES0cavity

SC0cavity
Crab0cavity

• add 9 klystrons and 3 PS’s more.
➡ One-to-one configuration for every ARES (One klystron drives one cavity).
• increase and reinforce WG systems.
➡ Upgrade of input coupler for the ARES (up to β~6, 800-kW input power capable)➡ Addition of new HOM Damper for the SCC as a measure against beam-induced HOM-power rising.
3Relocation of ARES Cavity for Phase-I
KEKB

SuperKEKB (Phase 1)@D4
added 3 KLYs &added 3 new LLRFs@D5
added 2 KLYs &replaced all LLRFs

Relocation of ARES cavities almost completed.
• Oho D4: Two cavities added.
→ 1:1 config.
• Oho D5: Six cavities moved from HER to LER.
• Fuji D7: Two cavities removed.
• Fuji D8: Two cavities removed.

4<Topic>

ARES

ARES Cavity

5<Topic>

ARES

ARES Cavity

Accelerator Resonantly-coupled with Energy Storage
3-cavity system stabilized with the π/2-mode operation
T. Abe (2014.03)

consists ofl HOM-damped accelerating cavity (A-cav),l Energy-storage cavity with TE013 (S-cav),(C-cav)l Coupling cavity
with a parasitic-mode damper.

fRF

508MHzUs / Ua

9

R/Q0

15Ω

Q0

1.1 x 105

Vc

0.5 MVPc

150 kWfor the π/2
accelerating mode

60 kW (acc. cav.) +90 kW (str. cav.)

Along the beam axis
Perpendicular to the beam axis

Successful Operation of the 32 ARES Cavities at KEKB

6

<Topic>

ARES

Relocation of ARES Cavity@Oho D5
ARES cavities along the LER beam line in Oho D5.

All of 6 cavities were moved
from HER to LER.
Photo View

e-

e+
7

<Topic>

ARES

Relocation of ARES Cavity@Oho D5
S-cav

C-cav

A-cav

e+

A-cav (+ C-cav) and S-cav are moved
separately, then connected with eachother after the installation.

Lip welding for vacuum seal at the flange connection between the coupling and storage
cavities was processed after the accelerating cavity aligned along the LER beam line.
8<Topic>

ARES

Performance Upgradeof Input Coupler
Fine grooving inside the outer conductor of thecoaxial line in order to suppress multipactoring
discharge for high power hadndling.

The coupling loop was extended to increase
the input coupling factor β. (up to β = 6)
The optimum coupling factor βopt is given by
βopt = 1 + Pbeam/Pc .

Input Coupler

Power Handling Capability (Spec.)
PinputPc
Pbeam
SuperKEKB: 750 kW = 150 kW + 600 kW
KEKB: 350 kW = 150 kW + 200 kW( βopt = 5 )Pc = 150 kW generating Vc = 0.5 MV per ARES cavity.
3D Transparent View of ARES Cavity System

9<Topic>

Production & Processing

ARESof Upgraded Input Couplers
Input	
  Coupler	
  
used	
  as
Output	  Coupler

ARES	
  Storage	
  Cavity

Snapshot of Status Monitor for RF Processing

Input	
  Coupler	
  Under	
  TestHigh Power
Test StandTo	
  1MW	
  Water	
  LoadRF	
  Power	
  from1MW	
  CW	
  Klystron	
  (TOSHIBA	  E3786)

Status & Plans

D4+D5 = 10 ARES’s (1:1)• So far, 13 input couplers have been processed up to 750-800 kW.
• Every ARES cavity in Oho D5 has been equipped with an upgraded coupler.
• Additionally in Oho D4, upgraded couplers will be installed in the RF stations eachconfigured as one klystron driving one ARES cavity before T=0.

10

<Topic>

DR-Cav

Damping Ring Cavity

11<Topic>

DR-CavAcc. Structure for the DR
T. Abe (2014.03)

Based on the ARES cavity with the long successful operation at KEKB
1. Accelerating-Mode Frequency: 508.887[MHz] (same as for the MRs)
2. Cavity Voltage (spec.): 0.7[MV/cav] (→Wall-loss power: ~120kW/cav)
3. Cavity Voltage (spec): 0.8[MV/cav] (→Wall-loss power: ~150kW/cav)
4. Max. stored beam current: 70.8[mA]
5. HOM absorbers: Silicon Carbide (SiC) tiles
6. Grooved Beam Pipe (GBP) common between cavities
7. Cavity-GBP Joint with a weld-ring gasket (not using a usual flange)
8. ”Multi Single Cell” structure
9. Reuse of high-power input couplers and tuners proven at KEKB-MRs/ARES
10. Good vacuum in cav. (~10-6[Pa]) needed for high-power input couplers.
11. Loss factor (incl. the taper sections): 2.4 [V/pC] (for σz=6.0mm)
12. No coupled bunch instabilities (CBIs) due to this structure occur.

We can supply total Vc : 2.4MV
at maximum.
Very low loading comparedto the (Super)KEKB-MRs
More compact than the SiC
bullets
Pumping port on each cavity

3-cavity concatenated system

3 cavies are driven by one klystronCommissioning will be started with 2 cavies. (The middle cavity is omitted.)12

<Topic>

DR-CavDR Cavity No. 2

High power test result of the Cavity No. 1 was reported last ARC.

The Cavity No. 2n Fabricated in JFY2013 with the same structure,method, and procedure as Cavity #1.
Inner surface of both end plates areelectropolished in the same way as the #1.
n High-power tested from May 12 to July 4 in2014

/cavity/cavity

Just after the delivery to KEK
In DR operation: 0.70 MV/cavity
13<Topic>

DR-Cav

Setup of High Power Testfor the Cavity No. 2@D1-A test standFine grooves against Multipactoring
Movable TunerTV Camera 3

Q-massHigh-Power Input Coupler

TV Camera 2

Directional
Couplers

TV Camera 1
Mirror Chamber １
Mirror Chamber ２
Header Cooling Pipes
Turbo-Molecular
Pump (300L/s)

Ion-Sputter Pump (400L/s)

LAN Cable (CAT.6)

Power Sensors
Power Meter

14

<Topic>

DR-Cav
No.1

Conditioning Histories
No.2

ü83 hours to reach 0.90MV/cavityü 95 hours to reach 0.90MV/cavityü107 hours to reach 0.95MV/cavity

Reported ’14

0.95MV

0.90MV→ stopped at reaching 0.9MV,
then migrated to stability test.

Conditioning was continued
until reaching 0.95MV.
(Radiation regulation limit @D1)

Auto conditioning sequencer was applied for the process.
The light blue lines indicate the reference vacuum pressure
specified by the computer controlled automatic aging.
If the vacuum pressure is higher than the reference, Pin isslightly stepped down until the vacuum pressure becomes
lower than the reference, and then Pin is slightly stepped up
as long as the vacuum pressure is lower than the reference.

üPin (Prefl) : input power to (reflected power from) the cavity
üWall-loss power: Pwall = Pin – Prefl = ~0.99 x Pin
üCavity No.2 reached 0.95MV/cavity successfully.
üComparable conditioning speeds btwn Cavity No. 1 and 2
15

<Topic>

DR-Cav

Stability Evaluation
with Keeping 0.90MV/cavity

After reaching 0.95MV,
Stability was evaluated bykeeping voltage at 0.9 MV
(In	
  DR	
  operaMon:	
  0.70	
  MV/cavity)

Example of the daily histories →keeping 0.9MV
keeping 0.95MV
for 30 min.

nCavity No.1: 3 breakdowns for 14.5 hours in total = 5.0+4.8-2.7 /24hrsnCavity No.2: 11 breakdowns for 80 hours in total = 3.3+1.3-1.0 /24hrs

Same stability between Cavity No. 1 and 2
within the statistics

16

<Topic>

DR-CavConclusion on Cavity No.2

nThe RF performance is equivalent to that of Cavity #1:lComparable conditioning speedlSame stability at 0.90 MV/cavity(In DR operation: 0.70 MV/cavity)“Passed“
Cavity #1 and #2 will be installed in the DR tunnel in
2016, and will supply a total Vc of 1.4MV to the DR.
• DR commissioning will start with 2 cavies.
• The fabrication of the No 3. relies on the budget.
• However, the need for the No.3 is not clear at present (It depends on the operation result).

17

<Topic>

SCC

Super-Conducting Cavity

18

<Topic>

SCC

Superconducting Cavity
8 modules have been installed in Nikko for HER.
Y. Morita

Pinput = 400 kW
Tested up to 750 kW.

Input Coupling Factor(Qext~50000) not changed

PHOM = 19 kW
Tested up to 19 kW.

Needs to be renewedsince some major parts
not available.

PHOM = 26 kW
Tested up to 26 kW.

Vc = 1.5 MV, Pbeam = 400 kW/cavity19

<Topic>

SCC

Large HOM Power

induced by high-charge and short-bunch beam(Presently-used)

SCC module

Ferrite Damper

Text

SBP ferrite damper

Copper Pipefor cooling

Stainless Steel Flange

LBP ferrite damper

Beam
Beam Pipe
150Φ
HIPped ferrite (thickness: 4 mm)• Expected large beam-induced HOM
power in SuperKEKB/HER
In design parameter, the HOM power isc a l c u l a t e d a s 3 7 k W / c a v i t y. A s
measures against the large HOM
power, the additional SiC damper wasstudied.
We have a lot of use-experiences of SiC, and SiC has several
advantages such as low-outgas, mechanical strength, easytreatment, .. etc.

SCC-HOM
parameters

KEKB

SuperKEKB(achieved, calc.)(design, calc.)

Beam Current

1.4 A

2.6 A

Bunch Length

6 mm

5 mm

Bunch Charge

10 nC

10 nC

Loss Factor

1.2 V/pC

1.4 V/pC

HOM power

17 kW/cavity

37 kW/cavity

20Simulation Studyof Additional SiC Damper<Topic>SCC

Wake field simulation using CST Particle Studio

1.3kW
load
8.7kW

Beam According to calculation using CSTInlet BPload
11.8kW

Outlet BP

particle studio with wakefield solver,
existing damper (LBP, SBP) loads are notlarge, but emission power through theoutlet beam pipe toward the downstream
cavity becomes to be large, 15 kW.
Eq.LF and Emitted Energies vs SiC Length

15.6kW (42%)

Eq. Loss Factor

Without SiC

With SiC (240mm)

Eq.LF[V/pC]

HOM Load
[kW]

Eq.LF
[V/pC]

HOM Load
[kW]

Total

1.38

37.4

1.94

52.5

Inlet BP
Outlet BP

0.05
0.58

1.3
15.6

0.05
0.20

1.5
5.4

SBP

0.32

8.7

LBP

0.44

11.8

0.34
0.44

9.2
12.0

SiC
240mm

--

--

0.90

24.4

HOM Power Emission throughOutlet BP

The emission power can be reduced to
1/3 by the additional damper. The load ofexisting dampers is not increased.
Additional damper can absorb more HOM
power emission as the length becomes
longer. In our practical condition, 240 mm
is suitable length.
21

Simulation Studyof Additional SiC Damper<Topic>SCC

Wake field simulation using CST Particle Studio

1.5kW
load
9.2kW

Beam According to calculation using CSTInlet BP

load
12kW

particle studio with wakefield solver,
existing damper (LBP, SBP) loads are notlarge, but emission power through theoutlet beam pipe toward the downstream
cavity becomes to be large, 15 kW.
Eq.LF and Emitted Energies vs SiC Lengthload
24.4 kWEq. Loss Factor

5.4kW

Additional SiC Damper

Without SiC

With SiC (240mm)

Eq.LF[V/pC]

HOM Load
[kW]

Eq.LF
[V/pC]

HOM Load
[kW]

Total

1.38

37.4

1.94

52.5

Inlet BP
Outlet BP

0.05
0.58

1.3
15.6

0.05
0.20

1.5
5.4

SBP

0.32

8.7

LBP

0.44

11.8

0.34
0.44

9.2
12.0

SiC
240mm

--

--

0.90

24.4

HOM Power Emission throughOutlet BP

The emission power can be reduced to
1/3 by the additional damper. The load ofexisting dampers is not increased.
Additional damper can absorb more HOM
power emission as the length becomes
longer. In our practical condition, 240 mm
is suitable length.
22

<Topic>

SCC

Development of
Additional SiC Dampers

New SiC damper modules were developed for SCC module. The SiC absorber
length is 120 mm, therefore, two damper modules are needed for one SCC module.
One SiC module needs to load 12 kW, because the expected HOM power loadedby the SiC is totally 24 kW at 2.6 A of beam current.

SiC damper module
Stainless steel flange

The additional SiC damper can be installed into downstream outside of gate valveof the SCC module. The cavity surfaces do not need to be exposed to the air. The
risk of degradation of the cavity performance can be avoided.

• Ferrite HOM damper (existing)• SBP damper:φ220x4x120

SBP ferrite damper• Additional SiC damper module• SiC : φ150x10x120• Cooing path: 5• Water flow rate: 15L/min• No. of modules: 2
LBP ferrite damper
Gate valve

Stainless steel jacket
Copper base

SiC (L=120mm)

Load Capability : > 12 kW

Cooling path

Beam
Beam Pipe
150Φ

Additional SiC dampers(to be installed)23

<Topic>

SCC

High Power Test Resultof the new SiC damper module

High Power Test Stand
SiC module

Absorbed Powers
Coaxial WG

Expected HOM load
at 2.6A: 12kW

Conditions and Results of High Power Test
Max. absorbed power: 18kW
Max. SIC temperature: 80 ℃
Max. flange temperature: 60℃
Cooling water: 15L/min
Inlet temperature: 25℃
Outlet temperature: 42℃

SiC Surface Temperatures

Expected HOM load
at 2.6A: 12kW

12 kW/module of absorption power, that is
expected HOM load, was achieved inenough low SiC surface temperature.

Conclusion:
We have established the new SiC HOM damper modules with adequate load performance for SuperKEKB !
Those modules will be installed into the beam line for confirmation of practical HOM damping effect.

24

<Topic>

HPRF

High Power RF System
Klystron
Kly. Power Supply
Waveguide system

25

High Power RF System<Topic>

HPRF(above-ground part)NS

to FujiOho

PS build.
D5 (for LER)+e

Water Pool-e

D4 (for HER)F

D5-F (1:1)

A

A C

H

D4-A (1:2)

Klystron

Klystron(for 2 ARES’s)

KPS

1.2-MW water load
(Cir. port#3)
to the tunnel(ARES)to IP

PS build.

Magic-T

30-kW dummy load
(Cir. port#4)
1.2-MW water load
(Magic-T port#4)

WR-1500

1-MW UHF circulator

WR-1500

400-kW
water load
(Cir. port #3)

30-kW dummy load
(Cir. port#4)

Examples of Site Condition

1-MW UHF circulator

Most components are about 30 years old. Maintenance of them is going on for all stations

26

<Topic>

Reinforcement @ Oho D4

HPRF
Oho

One type-B KPS will be moved to the DR in 2016
D4

KEKB
KPS
D4-AB
Type-A

Circulator

KPS
D4-DE
Type-A(Idle period)

KPS
D4-C
Type-B

KlystronA

C

B
A1,A2 ARES

Plan to manufacture
after T=0

Verticalthrough-holeto the tunnel

D

E

C1,C2 ARES

B1,B2 ARES

Relocation and reinforce ofthe high power RF system

For SuperKEKB (T=0)

Circulator

KPS
D4-EF
Type-A
(New)

KPS
D4-CD
Type-A

KPS
D4-AB
Type-A

KPS
D4-GH
Type-A

Makeup
Watar
Tank

Klystron

A B

C D
A B

C D

E F

to the tunnel

E F

G H

G

H
27

<Topic>

Reinforcement @ Oho D5

HPRF

One type-B KPS was moved to the D2 (for a test station)

KEKB

Oho
D5

KPS
D5-DE

KPS
D5-C

KPS
D5-AB

Type-A

Type-B

Type-A

Circulator
KlystronE

DC

to the tunnel

B

E, C

Circulator&1.2-MW WL

Pump
Unit

Type-A

B1, B2

A1, A2

The all works of relocation and reinforcement for D5
were completed.
All stations were changed to 1:1 configuration

For SuperKEKB
KPS
D5-EF

A

to the tunnel

Makeup
Watar
Tank

KPS
D5-CD

KPS
D5-AB

Type-A(New)

Type-A

KlystronF

to the tunnel
F E

E

D C

D

C

to the tunnel
B A

B

A
28

<Topic>

HPRF

Status & Plan of HPRF System(Summary)

Klystron‣Klystron: Klystron set up (D4: +3, D5: +2, D10: exchange for Toshiba) : finished: Manufacture of the cooling system for the reinforced stations (D4, D5) : finished

Air Cooled Heat
Exchanger

KPS(Klystron
Power Supply)(Klystron
Power Supply)‣KPS: Additional Two power supplies set up for the reinforced stations (D4-EF, D5-CD) : finished: Maintenance for the existing power supplies (D4, D5, D10, D11) : finished(D7, D8 ) : will be finished in October 2015

Klystron Cooling
SystemHigh-powercomponents
components‣High-power: Connection of the waveguide system : will be finished in March 2015
: Manufacture of new 1.2 MW water loads (D4: 6, D5: 6 -> total 12) : finished
set up to the stations : finished: Overhaul of the existing 1.2 MW water loads (19 loads) : finishedreplaces to the stations : will be finished in June 2015
: Manufacture and set up of the 30 kW dummy loads (25 units) : finished: Manufacture of the cooling system for the 1.2 MW water loads (D4, D5): finished: Maintenance of 1MW UHF circulators : will be finished in August 2015**Other maintenance work: will be finished in October 2015 **Addition and relocation for reinforcement were almost completed.
High power RF system will be all done well in advance of operation start.

29

<Topic>

LLRF

Low Level RF Control System

30

<Topic>

LLRF
Existing KEKB
Analog LLRF System( for one klystron )New LLRF Control System
has been developed for higher accuracy and flexibility.
Existing LLRF controls systems will be replaced with new ones step-by-step.

Block Diagramof FB & Tuner Cont.
Replace

New LLRF Systemfor one klystronµTCA crate

uTCA-platform
FPGA Boards(AMC Card)

16-bit ADC x 4ch,
16-bit DAC x 2ch

EPICS-IOC embedded

The good performance was demonstrated in the high power test with ARES cavity,
and the regulation stability was 0.02% in amplitude and 0.02 deg. in phase.

The µ=-1 mode feedback would be applied to a few or somestations. (Not to all stations)• Consisting of µTCA-platformed FPGA boards (AMC), & PLC.
• EPICS-IOC with Linux-OS is embedded in each of them.
• Common hardware for both of ARES & Superconducting Cavity.
• Klystrons (LLRF) : Cavity unit = 1 : 1 (SuperKEKB)

If not enough, The -1 mode signal will be distributed to the other stations.
In the KEKB operation, the µ=-1 mode FB was applied to only one station in eachring respectively and it was enough effective.

31

<Topic>

LLRF

Installation Status of new LLRF
@OHO D4 Control Room
Old systems

3 new LLRF
systems

SCC

Nikko

ARES
KLY+LLRF

Oho

+

Fuji
6 new LLRF
systems

Status & Plan

@OHO D5 Control Room

• New LLRF control systems were installed to 9 klystrons stations at Oho D4&D5 (6@D5 + 3@D4) , and the cabling wascompleted.

• The other stations will be operated by existing systems in the Phase-I. D4 stations are mixing the new and old systems.
• The RF cable loss measurement and the overhaul of the old systems were also finished for all stations.
• The new operation interfaces (GUI) for the acc. operators, which integrate both the new and old systems, should be
prepared before the phase-I starts.

• The DR-LLRF control system is almost the same as MR one, except 3-cavity vector-sum control is needed. It will be
produced and installed in JFY2015.

32

Implementation of KLY-PLL<Topic>

LLRF

for Compensation of KLY Phase Change due to Anode Voltage Control

Reported ’13
For efficiency optimization, the anode voltage is controlleddepending on klystron input power to reduce the collector loss.

KLY Anode Voltage

Input Power
KLY-PLL

Kly Input-Output Characteristics

Klystron Phase Lock Loop (KLY-PLL) was implemented
digitally in the FPGA for the cavity I/Q-FB control. (onlyphase compensation without KLY-AGC)

Reported ’14

80 deg.

The successful working was demonstrated
in low level test last year, but..

The phase shift of 80 deg. will be criticalproblem for I/Q FB control technique. ( Acceptable: ~60 deg. )Necessity for the high-power test with
klystron was pointed out in the last ARC

33

High Power Test @ 800 kW
for the KLY-PLL control<Topic>

LLRF

This test was including just
klystron checkup for highpower output of 800 kW.

LLRF System

It was the first time to output
over 800-kW since the KEKB
operation closed.

KLY
Kly. Loop Delay ~ 1us

1.2-MW Dummy Load

Loop Delay ~ 2us

Tuner
Cont.

Klystron

A-Cav

ARES Cavity
Simulator

C -Cav
S -Cav

Reflect

Cav-In

LLRF System

Tuner
Cont.

Latency: 800ns

Circulator

INTL
Cont.

Auto tuner and Beam loading canbe also simulated in real time.

ARES Cavity
Simulator

1.2-MW
Dummy
Load

34

<Topic>

High Power Test Results

LLRF

of the KLY-PLL and cavity FB control using ARES cavity simulator

Anode Voltage
The coefficient is optimized
for 850-kW max. output.

by using ARES Cavity Simulator
under the Closed Loop

Beam Loading Simulation

750kW

KLY Out

Kly-Input(@Ib=3.6A)
Φs=80deg.

KLY In/Out Characteristics
Operation:
750 kW

β=5

A-Cav Phase (simulator)
Auto Tuning Pulse Counts(@Ib=0)

Cavity VSWR

270kW
Compensated Phase by PLL

A-Cav Amp.(simulator)(simulator)(A-cav detuning: -290kHz)(Equivalent to 150-kW Cav-In for β=5)

Output Power
Regulation Stability @ 750 kW
Under Closed Loopof I/Q-FB & KLY-PLL

Amp.

0.1%.

Phase

Klystron linearity & gain is very goodin the operation range.

KLY-PLL worked successfully over 800-kW output range,
and no problem was found in the cavity FB control.

0.08 deg.

4 ms

35

Summary
The rearrangement and reinforcement of components are almost completed for Phase-I.
The remaining works to do will be done in advance of the RF conditioning start in 2015.

1. ARES Cavity• Relocation has been completed.
• 13 input couplers have been processed up to 750-800 kW.
• Upgraded input couplers has been installed for all ARES’s of D5 stations➡ Upgraded input couplers will be installed for D4 stations of the one-to-one configuration, beforeT=0 .

2. DR-Cavity• High Power Test of the Cavity No.2 was done, and the good performance as equivalent to that of the No.1 wasdemonstrated.
➡ The two cavities will be installed in the DR tunnel 2016. (Vc=1.4MV can be supplied.)• The fabrication of the No 3. depends on the budget (The need for the No.3 is unclear).

3. Superconducting Cavity• Additional HOM damper is required, then new SiC absorber was developed to reduce HOM-power emission.
• Good performance of the new HOM damper was verified by the high power test.
➡ The new HOM dampers will be installed into the beam line to confirm the effective performance in beam test.

4. High Power RF System• Rearrangement of klystrons and the power supplies were completed.
• Manufacturing of the reinforced HPRF components were completed.
➡ The remaining maintenance and connection of the waveguide system will be done in 2015

5. Low Level RF Control System• Installation of 9 new LLRF control systems and the cabling were completed at D4 and D5. The existing systems arealso used for the other stations. The LLRF hardwares for the MR are ready.
• KLY-PLL implemented in the FPGA worked successfully in the high power test.
➡ For the acc. operators, new user interfaces integrating the new and existing systems should be prepared.
➡ The DR-LLRF control system will be produced and installed next JFY.

36

Tank youfor your attention!

37

Backup Slides

38

Fundamentals of the ARES Cavity System
T. Kageyama, 2011.02

Δfπ/2 = ΔfA / (1+US/UA )-28 kHz-280 kHz

9

Detuning against beam loading

Flywheel Energy Ratio US/UA = 9 not changed.
39

T. Kageyama, 2011.02

Fine circumferential grooving on the outer conductor surface
in order to suppress multipactoring discharge.

T. AbeSuccessfully tested and used in actual KEKB operation.
40

T. Kageyama, 2011.02

Input Coupling Factor vs. Loop Height-3 %Unloaded Q Value

β (Input Coupling Factor)

copper spacers

Prototype

KEKB

Loop Height [mm]Loop Height
K. Yoshino, H. Sakai, T. Kageyama

A prototype coupler with a loop height of 60 mm
was fabricated in JFY 2009.
41

Instability due to RF cavities and cure
Instability due to RF cavities and cureT. Kageyama, 2011.02

Ring

Longitudinal/Transverse

Cause

Frequency (MHz)Growth time (ms)

Cure

LER

Longitudinal

ARES-HOM

1850

12

B-by-B FB

ARES-0/π

504

21

B-by-B FB-1 mode508.794-1 mode damper

LER

Transverse

ARES-HOM

633

7

B-by-B FBHERLongitudinal

ARES-HOM

1850

59(no need)

SCC-HOM

1018

58(no need)-1 mode508.794-1 mode damper

ARES-HOM

633

39(no need)

SCC-HOM

688

14

B-by-B FBHERTransverse

Longitudinal bunch-by-bunch FB will be needed
to suppress coupled bunch instabilities driven by RF cavities.
42

e-

e+

1.5 MV

7 GeV x 2.6 A

4 GeV x 3.6 A

P beam 400 kW

Vc = 15~16 MV

Vc = 9.4 MV

Pbeam = 8.0 MW

Pbeam = 8.3 MW

by

by

Vc

D11

8xARES + 8xSCC

22xARESNIKKOD10LER ARES

1 : 1

1 : 2

Vc

0.48 MV

0.34 MVP wall140 kW

70 kW

P beam

460 kW

230 kW

Input β

4.3

4.3

PPMD

14 kW

7 kW

Vc

0.5 MVP wall150 kW

P beam

600 kW

Input β

5.0

PPMD

21 kW

OHO

HER SCCHER ARES

D4SuperKeKB L = 8 x 1035 cm-2s-1

T. Kageyama, 2011.02

D5

RF Power for Ultimate Stage

Klystron
SCC
ARES

D8

FUJI

D7

2010.11.25

43

22 ARES Cavities
operated for LER (Ib=3.6A)
T. Kageyama, 2011.02

RF frequency

508.869 MHz

Flywheel Energy Ratio US /UA

9unchanged

Cavity Voltage Vc

0.48 MVP(wall) = 140 kW

Detuning Frequency Δfπ/2 / ΔfAC

-28 kHz / -280 kHz

P(beam) = 460 kW

Input Coupling Factor β

5.0

β (optimum) = 4.3

CBI (-1 mode) due to the Acc. modeτ = 4 ms

RF feedback

CBI due to the 0 and π modesτ = 21 ms

bunch-by-bunch FB

44

HOM Power Estimation for LER
T. Kageyama, 2011.02
KEKB LER
Sep. 21, 2004

SuperKeKBLERPower Handling Capability
verified at 1.25 GHz

Factor of Safety

Ibeam [A]

1.6

3.6

-

-

Nbunch

1293

2503

-

-

σz [mm]

7

6

-

-

k [V/pC]

0.40 (0.39†)

0.44

-

-

PHOM /ARES
[kW]

5.4†

17

-

-

PHOM /HWG
[kW]

1.05†

3.3

5.0

5.0/3.3 = 1.5

PHOM /Groove
[kW]

0.3†

0.93

1.2

1.2/0.93 = 1.3†based on calorimetric measurement

45

The -1 mode feedback
In the KEKB Operation• Beam current was limited due to the -1 mode
instability at 1 A in LER and 1.2 A in HER, much
lower current than expected.
• The -1 mode digital feedback selectively reduces
impedance at the driving frequency.
• After the -1 mode feedback was installed, thebeam current could be successfully increased.

1600
1400
1200
1000

Stored beam current

800
600
400
200
0

Feedback off
3:30 PM
03.6.30

Feedback on

3:45 PM

4:00 PMDate

FB OFFƒrf - ƒrev-40

ƒrf - ƒrev + ƒs

(a)

-0.97

-0.95

-60
-80
-100
-120

-1

-0.99

-0.98

-0.96

Frequency Δƒ/ƒrev

-1 mode sideband

FB ON
ƒrf - ƒrev

-40

(b)

-60

ƒrf - ƒrev + ƒs

-80
-100
-1

-0.99

-0.98

-0.97

-0.96

Frequency Δƒ/ƒrev

-0.95

46

ARES Cavity Simulator
T. Kobayashi, et. al., Proc. of the 9th Annual Meeting of Particle Accelerator Society of Japan, WEPS121 (2012)
ARES Cavity Simulator
IQ-Sampling of IF Signal
Ref. 508.9MHz
LO

1/6

530.1MHz508.9MHz

1/4

508.9MHzIF

RF Input

21.2MHz

CLK

84.8MHzADC

The ARES Cavity

Tuner control pulses (rear panel)
S-Tuner A-Tuner Beam
Signal Signal Intensity

Ref.

IQ-ID

508.9MHzRF Input（508.9MHz）

I/Q
DeM

CLK

(+10V, 10us, 2kHz)I

Δωs Δωa

ADC

Ib

ADC

I
DAC
DAC

Q

Reflection

Ref.

Pulse Train (CW/CCW)

I,Q

RF Input

T. Kageyama, et. al.

I/Q
Mod

508.9MHz

I/Q
Mod

Cav-S

Q

DAC
DAC

3-Cavity System
Simulator（FPGA）DAC
DAC(Pick-up)

I/Q
Mod

Cav-C
(Pick-up)

DAC
DAC

I/Q
Mod

Cav-A
(Pick-up)

Ref.

A-Cav
C-Cav

S-Cav

⎡ V n+1 ⎤ ⎡ 1− Δt ⋅ ω
a/2⎢ Ar ⎥ ⎢n+1⎢ VAi ⎥ ⎢ΔtΔω a⎢ n+1 ⎥ ⎢0
⎢ VCr ⎥ ⎢=⎢ V n+1 ⎥ ⎢ −K Δt ⋅ ω Q
ac/2 c⎢ Ci ⎥ ⎢n+1⎢ VSr ⎥ ⎢0
⎢ n+1 ⎥ ⎢0⎢⎣ VSi ⎥⎦ ⎢⎣Reflectionn⎧ n+1
Rs I Gr
n
V
=
β
⋅V
−
Sr
⎪ Rr
2 β
⎪
⎨
n
⎪V n+1 = β ⋅V n − Rs I Gi
Si
⎪ Ri
2 β
⎩

β、Qµ、 ΔωµRef.

RF Output
Reflection, A, C, S-cav.

−ΔtΔω a0

K a Δt ⋅ ω a/2Qa0

1− Δt ⋅ ω a/2−K a Δt ⋅ ω a/2Qa00

K a Δt ⋅ ω c/2Qc

1− Δt ⋅ ω c/2−ΔtΔω c00ΔtΔω c1− Δt ⋅ ω c/2−K s Δt ⋅ ω c/2Qc00

K s Δt ⋅ ω s/2Qs

1− ( β + 1) Δt ⋅ ω s/2

0−K s Δt ⋅ ω s/2Qs0

ΔtΔω s(1)Time-evolutionary simulation of baseband (I,Q-components) by FPGA in real-time.

(2)
(3)
(4)
(5)
(6)

Simulation of 3-cavity coupled system (π/2 mode operation).
Direct RF signal (509MHz) input & output.
Cavity reflection signal is simulated in real-time response.
Tuner control (tuning/detuning) can be also simulated with pulse train signal input.
Beam loading effect can be included.

(7)
(8)

Cavity parameters is variable arbitrarily.
Bench-top use or rack mounting⎤⎡ Vn⎥ ⎢ Ar⎥ ⎢ VAin0⎥⎢ n
K s Δt ⋅ ω c/2Qc⎥ ⎢ VCr⎥⎢ Vn
0⎥ ⎢ Ci⎥ ⎢ VSrn−ΔtΔω s⎥⎢1− ( β + 1) Δt ⋅ ω s/2 ⎥ ⎢ VSin
⎦⎣
0

Δt =

1
fclock⎤ ⎡ Δt ⋅ ω R I n
a/2 A Br⎥ ⎢⎥ ⎢ Δt ⋅ ω a/2 RA I Bin
⎥ ⎢
0
⎥ ⎢
+
⎥ ⎢
0
⎥ ⎢
n
⎥ ⎢ Δt ⋅ ω s/2 Rs I Gr⎥ ⎢n⎥⎦ ⎢⎣ Δt ⋅ ω s/2 Rs I Gi

ω µ /2 =ωµ
2QµΔω µ = ω µ − ω rf : Detuning

Kµ =

kµ
2

⎤
⎥ Beam Loading⎥ Term⎥⎥⎥⎥⎥⎥Cavity Driving⎥⎦Termµ : s, c, aβ :Input Coupling: Coupling factor with C-cav.

Rµ : Shunt Impedance

47

Response Property -Klystron Bandwidth(open loop)

Measured Result
Amplitude @dBD
10

10k

100k

Magnitude

1M

Frequency @HzD

Modulation Frequency [Hz]Td : Delay

Magnitude [dB]0fitting curve with

H kly [s] =

-10

-20

1
1+ s / ω kly + s 2 / αωkly=130 kHz

Phase

Td=650ns
α=2.1x1012-30

Phase@deg.D
180i e− s⋅Td

10k

100k

1M

Frequency @HzD
Phase@deg.D
180

10k

100k

1M

Frequency @H

Phase [deg.]

90
90

0

-90

Phase（delay=0）

0

-90

-180

-180

48
31

Disturbance Rejection Characteristics
x

fN

+
+

KLY

Delay

PI-cont+

CavityDelayin the closed loopyy=H[s]•x

Ref.
Amplitude @dBD
Magnitude
(h11)
10
0

1k

Calculation & Measurement
10k

100k

Frequency @HzD

1M Phase@deg.D
180

OpenLoop

1k90Frequency

10k

100k

1M

10k

100k

1M

Phase

-10
-20

0

P20,I20-90-30

P8, I40-40

P20,I20-180

Phase@deg.D
180

P20,I801kFrequenc

90

-50

0

P8, I40-90

Sync. Osc.

fs

Revolution-18049