Normal Conducting Accelerating
Cavities for the MRs and DR
of SuperKEKB
Tetsuo ABEFor SuperKEKB‐RF / ARES‐Cavity Group(T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi, and K. Yoshino)

The 18th KEKB Accelerator Review Committee Meeting
March 4, 2013

Main Ringg (MR)() Cavities

1

Accelerator Resonantly‐coupled with Energy Storage
3-cavity system stabilized with the /2-mode operationconsistsioff HOM-damped accelerating cavity (A-cav), Energy-storage cavity with TE013 (S-cav), Coupling cavity(C-cav)
with a pparasitic-mode damper.
pAlong the beam axisP
di l tto thi
Perpendicularthe bbeam axis

With Long Successful Operation at KEKB

2

Fundamentals of the ARES Cavity System

Δf a
Detuning against beam loading: Δf / 2 = fa / 10
1  Us / Ua
3

Upgrade/Work Main Items on the MR Cavities(*) F
For more ddetails,t il see th
the K
Kageyama’s’ presentationt ti slides
lid att MAC’11

1. Detuning against the beam loading at SuperKEKB‐LER / 22 ARES cavities with 3.6A (Appendix A) f/2 = fa/(1+Us/Ua) = ‐280kHz/10
280kHz/10 = ‐28kHz
28kHz < frev=99kHz
99kHz (*)
 Flywheel Energy Ratio: Us/Ua= 9 not changed (*)

2. CBI issues for SuperKEKB‐LER with 3.6A
 lCBI d
due to theh ‐1
1 moded ((t = 4ms):4 ) cured
d by
b the
h RF FB (‐1( 1 mode
d ddamper)) (*)
 lCBI due to the impedance imbalance between the 0 ‐  modes (t = 21ms): cured by the longitudinal BxB FB (*)
 lCBI due to the HOM impedance @1.85GHz (t = 13ms, Appendix B): cured by the longitudinal BxB FB (*)

3 HOM loads
3.
 WG Load: 5kW/WG verified at the test stand ( > 3.3kW/WG at SuperKEKB‐LER with 3.6A) (*)
 GBP Load: 1.2kW/Groove verified at the test stand ( > 0.93kW/Groove at SuperKEKB‐LER with 3.6A) (*)
 Increasing the cooling capabilities of the WG and C
C‐damperdamper loads

4. Installation of 2 ARES cavities to the D4 station for HER  done (*)
5. Relocation of the ARES cavities in the D5 station  done
 6 cavities
cavities: HER  LER

6. Removal of 4 sets of ARES cavities from the D7&D8 stations  done
7. Improving the vacuum evacuation system by introducing NEG pumps4Upgrade/Work Main Items on the MR Cavities(*) F
For more ddetails,t il see th
the K
Kageyama’s’ presentationt ti slides
lid att MAC’11

8. Input couplers with strengthen input coupling (max = 56) needed for stations with theyconfigurationg
Klys:Cav=1:1
 The coupling loop extended (17  60mm) as shown in the photos below (*)
 The prototype coupler successfully conditioned up to Pin=800kW at the D1‐A test stand (*)
 The prototype coupler verified up to Pin=770kW and Pbeam=610kW (> SuperKEKB spec.: Pbeam=600kW) at the D5‐C
station duringdtheh KEKB operation (*)
 So far, we have 4 couplers successfully conditioned at the D1‐A test stand.
 Now one coupler is being high‐power tested up to Pin=600kW (as of March 1, 2013).
 In JFY2012 (JFY2013),(JFY2013) we will obtain 5 (10) more couplers to be highhigh‐power
power tested.
tested It takes about one month in total for one coupler to be well‐conditioned, including the setup work (Appendix O).

9. ?

Used at the KEKB-MRs

With strengthen input coupling for the SuperKEKB-MRs

5

We need 14 well‐conditioned input couplers with strengthen input coupling
for stations with the Klys:Cav=1:1 configuration
around T=0.

Input couplers
t be
tob replacedld iin TT<00

Input couplers to be replacedin T<0 or in the first long shutdown
of SuperKEKB.
6

Damping
p g Ringg (DR)( ) Cavities

7

RF Accelerating Structure for the DR
Based on the ARES cavity with the long successful operation at KEKB
1. Accelerating-Mode Frequency: 508.887[MHz] (same as for the Main Ring (MR)
2. Cavity Voltage (spec.):
0.7[MV/cav] (Wall-loss power: ~120kW/cav)
3. Cavityy Voltageg ((challenge):g ) 0.8[MV/cav] ((Wall-loss power: ~150kW/cav))
4. Max. stored beam current: 70.8[mA]
5. HOM absorbers: Silicon Carbide (SiC) tiles (Appendix D)
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 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): 2.5 [V/pC] (for zmm)
12. No coupled bunch instabilities (CBIs) due to this structure occur (Appendix N).

We will use a 1MW klystron.
Very low comparedto the (Super)KEKB-MRs
More compact
than the SiC bullets
Pumping port on each cavity(Dimensions in mm)

400
Taper
p
Flange

1100

40


15
50

72

50
1200

Taper End

150
128
72
5308

50

50

300

150

256 150
72

72

300
50

200
Bellows

Taper EndBlue : Vacuum
Gray : HOM absorber (SiC)

We can supply total Vc : 2MV.

110
GV
8

Four Types of Components
1. Cavity (main body) (Appendix H)
2. HOM(Higher-Order-Mode)-WG(WaveGuide) load (Appendix I)
3 GBP (btwn) (Appendix J)
3.
4. GBP (end) (Appendix K)

Joint:

Welding for vacuum sealingRF shield inside Assembly of the above components like LEGO blocks

9Cavity‐GBP Joint Structure

ARES
Joint btwn C-cav and S-cav

(F th
(For
the d
details,t il see A
Appendix
di E
E.))

SUS

Weld Ring Gasket with Lip Sealing, like:“Welding  Disassembly ReWelding”
Possible Several Times

Finger-type RF shield- Successful experience at KEK/PF:

Be-Cu, @KEK/PF(Fixed with 16 M12 bolts)

Used in the Single-Bunch-Mode Operation- BeamB
current:
t 70 mA
A ((max.))- Bunch length: 24 mm
10Historyy and ScheduleYear
JFY2011

JFY2012

Items

Remarks

Cavity No.0 (prototype) x 1
GBP(btwn) (prototype) x 1
HOM‐WG load (prototype) x 1→High‐power tested at D1‐A test stand (finished)→High‐power tested at D1‐C test stand (finished)

Cavity No.1 x 1
HOM‐WG load x 4
GBP(btwn) x 1
GBP(end) x 1
GBP(dummy) x 1←Feedback from the prototypes

We are HereHere.

JFY2013Cavity No.2 x 1
HOM‐WG load x 4
GBP(btwn) x 1
GBP(end) x 1

JFY2014

Finish High Power Tests.
Installation to the DR tunnel

CY2015

Start of DR commissioning with Cavity No.1 and No.2 (Appendix F)

20XX

Cavity No.3
HOM WG load x 4
HOM‐WG

If needed

11

High
h Power Test (HPT)()
of Cavity No
No.0
0 (Prototype)12

Cavity No.0

 Just after the delivery
 No cooling pipes yet
 The support hascomplete alignment
mechanism.

(LM: Linear Motion)

LM GuidePerpendicular to the beam axis
LM guide along the beam axis to be added to Cavity No.1-3

13Cavity‐GBP Joint (Cavity No.0)
O-ring (rubber) for vacuum sealing during the HPT

For the details,
see Appendix E.

Welding lip for vacuum sealing

C it Sid
CavitySide

GBP Side
Sid

RF fingers

14Note: this test stand is also used for input-coupler conditioning.

Setup at D1‐A Test Stand

Waveguideg((WR-1500))
Input Coupler (reuse)
G
Grooves against Multipactoring

Movable Tuner(reuse; T . Kageyama)

TV Camera

Cavity No.0
Turbo-molecular
Pump

Sputter Ion Pump
Vacuum
Evacuation
System (H. Sakai)

Header Pipes(Y. Takeuchi)

Directional
CouplerLo Po er RF meas
Low-Power
meas.

Simulation(For Cavity Temperature: 20degC)(100%IACS assumed)Q0(cold)(ssim)

Q0(ccold)(meeas)

Check of the Unloaded Q (Q0)

(Tuner Position: 15mm inside (home position))Q0(cold)(meas) / Q0(cold)(sim) = 93% (OK)16

天Check of the External Q (Qext)
水平of the Input Coupler

Angle(by Low
Low-Power
Power meas
meas.))地HSet (cold) = Q0(cold) / Qext
=1.34 (over-coupling)> (HP)(HP: High Power)

Good Agreements between the meas. and simulation

17

How to Calculate Cavity Voltage (Vc )Pin , Prefl: Input and Reflected RF powers measured, respectively
Assuming the cavity to be tuned
Input Coupling Factor :

l

(HP)

(over-coupling)l

Unloaded Q :

(HP)

(HP)

(We use Qext= 21814 from the LP meas.)(LP: Low Power)

Shunt Impedance
p
:

(HP)

(HP)

(HP)

(HP)

(We use Rsh(HP)/Q0(HP) = Rsh(cold)/Q0(cold) =150from the simulation.)

Cavity Voltage :

(HP)

||
Pwall

18

RF Power Measurementswith Power Meters located in the D1 Control RoomIn the Radiation ShieldIn the D1 Local Control Room
Input Power to the Cavity: Pin

Reflected Power from the Cavity:y Prefl~70m-longC
Coaxiali lCablesDirectional
Couplers
19

Calibration Data taken on the Last Day↓

180kW (max.)
200 kW (max.)l(== Pwall)

Conditioning History●●Pin > 0
Plotting●Automatic Aging On
Conditions ●Pin < Ptarget

0.86MV(max.)
0.9 MV (max.) Pin and Prefl calibrated for calorimetricpowers to have Vc/Vc<3% Pin controlled to have the vacuum
pressure lower than the specified
value (shown as a light-bluelight blue line) in
the automatic conditioning program.
 As the conditioning progressed,
 Better vacuum Continuous emission in the cavity
observed with the TV camera
darker Vc=0.9MV/cav : max. limit due to theradiation level outside the facility.

Conditioning Time [hours]

If we weld the lip at the Cav.-GBP joint
without a O-ring (all metal),
we expect ~1x10^-6 Pa during HP operations.

20More Radiation Shields at D1‐A

(T. Kageyama)in addition to the permanent lead wall surrounding the cavity
At the beginning of this HPT,
we put lead blocks.

Thentoward higher Vc

Then

Finally,,,

more

And

more

21

(with a usual sensitivity)“Lightnings” observed with the TV camerain the early hours of the conditioning

Coupling loopof the input coupler

E.g. Pin = 20kW (Vc = 0.3MV)
Just after the 2nd lightning,lightning I/L(refl
I/L(refl.)) worked
worked.
No vacuum-pressure spike
Before the Lightnings

1st Lightning

2nd Lightning

After the cavity was well-conditioned,
 No “Lightnings” observed Almost no continuous emissions observed using a usual camera(however, using a highly-sensitive camera  Appendix G)

TV camera

Measurements of the Temperature Increaseof the Cooling Water for the Cavity

空洞冷却水（入側）温度：３０℃[MV/cav]
Pin = ~10kW

Pin = ~200kW

24

Q0(HP))

Measurements of Q0 v.s. Vc

5%[MV/cav]
Pin = ~10kW

Pin = ~200kW

25

Longest Vc Holding Times 0.9MV/cav (Pwall=200kW) => 8 min. (2012‐09‐07_11:03:30‐11:11:30)

 Terminated by I/L(refl.) with no vacuum‐pressure spike and no discharge in the TV camera We could not p
perform longer
g runs due to the radiation level outside the facility.
y 0.8MV/cav (Pwall=150kW) => 8 hours (2012‐07‐25_09:38‐18:12)

 Terminated by I/L(refl.) with no vacuum‐pressure spike and no discharge in the TV camera We cannot distinguish where is the primary cause, in the cavity or the LLRF control system.
In addition, we met the following two problems: (1) and (2) related to the LLRF control
system.
(1) The cavity was not tuned automatically in case of higher cavity frequencies.
 Solved with replacing the f-1 module by new one late in this HPT(with the help of the RF Control Group)
After replacing all the relevant LLRF modules, the following problem still remains unsolved.
(2) RF powers (Pin and Prefl) measured in the D1 control room fluctuated.
 RF powers measured in the radiation shield did not fluctuate.
 Cable deterioration?

Solving the above problems,
we will perform Vc-holding endurance tests for Cavity No.1 (Appendix M).

26

High Power Test (HPT)
off theth GBP Prototype
P t t

27

GBP (btwn)
Material: SUS
4
4 sets of SiC tiles (same as used for the HOM-WGs)
HOM WGs)
Max. HOM Power absorbed: ~200W/GBP (incl. the loss factor)
Max. Accl.-Mode Power absorbed: ~100W/GBP (for Pwall=180kW)
Loss factor: 0.2 [[V/pC]
p ] ((for zmm))(Dimensions in mm)

4-R10
4-R3
4
R3

544
340

45deg
4-R2

30

(Cross-section perpendicular to the beam axis)(Along the beam axis)

28

L-band Klystron(1.25GHz)

Setup at D1‐C Test Stand(Y. Takeuchi)

GBP
Gauge #1
TV camera
RF Power
Gauge #
#2

 Converting WG (WR-650GBP)
Load: Winged Chamber Prototype (see Appendix C)

544mmLips not welded; O-rings used for vacuum sealing30

Holding
for 1 hour
10min.

RF Power to the Load (P( f) [kW][]ed in all thhe SiC Tiles [kW]RF Power Absorbe

Vacuumm Pressure [Pa]Results of this HPT (1/3)

RF Power to the Load (Pf) [kW]No Vacuum-Pressure SpikeNo Abnormal Temperaturep
Increase
No Discharge Observed with the TV Camera

Pf(max) = ~3.4kW
Prefl(max)= ~10W
Max. Power Absorbed at the GBP: ~400W/GBP ( > 300W/GBP: max. power from the simulation 31)

Results of this HPT (2/3)~~ Visual Inspection of the SiC Tiles ~~No Damage on the SiC Tiles!
32

Results of this HPT(3/3)~~ Visual Inspection of the RF Fingers ~~Upstream

Downstream

No Damage on the RF Fingers!
33

Status of Cavityy No.1

34

Status of Cavity No.1
• By scraping the tuning bump, the accl.‐mode frequency was tuned
into “508.904MHz” for the conditions:– Tuner position: 15mm inside (home position)– Cavity Temp.: 30degC– Inside: Vacuum(Only 17kHz away from the target frequency of 508.887MHz)• Almost in the final stage
g of the fabrication→ To be delivered soon

• News
1. The inner surfaces of the two endplates of the cavity: Electro‐Polished (EP).
→ Faster conditioning and/or lower trips rate are expected. (next page)2 Preparing to take video pictures of the inner surfaces of the endplates during
2.
the high power test of Cavity No.1.

• X
35

1. EP for the Endplates of Cavity No.1
Material: OFC Class1 (C1011-C1)(C1011 C1), ~40m
40m EPW/o the tunin
ng bumpp

BeforeRa=~1.5m
Ry=~8m

W/ thee tuning bump

500

After

Ra=~0.2m
Ry=~1m

Status of Cavity No.1
• By scraping the tuning bump, the accl.‐mode frequency was tuned
into “508.904MHz” for the conditions:– Tuner position: 15mm inside (home position)– Cavity Temp.: 30degC– Inside: Vacuum(Only 17kHz away from the target frequency of 508.887MHz)• Almost in the final stage
g of the fabrication→ To be delivered soon

• News
1. The inner surfaces of the two endplates of the cavity: Electro‐Polished (EP).
→ Faster conditioning and/or lower trips rate are expected.

2 Preparing to take video pictures of the inner surfaces of the endplates during
2.
the high power test of Cavity No.1.

• X
37

2. New Eye to See the Inside of the Cavity
What’s going on, during HPTs, around theinner surfaces of the endplates
where the surface fields are at maximum.

TV camera
to be attached(H. Sakai)

Replace this blank flange by:

Mirror (Made of Al, packed yet in this photo)

TV camera
to be attached38

Summary on the DR Cavities (1/2)
1. The accelerating structure for the DR
 Based on the KEKB‐MR/ARES cavity with the long successful operation at KEKB Can supply total Vc = 2MV (spec.)

2. High Power Test of Cavity No.0 (Prototype) After 90hrs conditioning, Vc=0.9MV/cav (Pwall=200kW) achieved> 0.8MV/cav (challenge)
These V values are corrected>> 0.7MV/cav
0 7MV/cav (spec.)(spec )
with recalibration for calorimetric powerscand powers measured in the rad. shield→“Pass“3 High Power Test of the GBP Prototype3.

 Up to the RF power absorbed in the SiC tiles: 400W/GBP From the simulation, the max. power is 300W/GBP, including the HOMs, loss factor,
and
d the
h accelerating
lmode
d withh Pwall=180kW.
k
 No vacuum‐pressure spike, no abnormal temperature, no discharge
 No damage on the SiC tiles and the RF fingers→“Pass“
39Summary on the DR Cavities (2/2)
4. During this HPT at D1‐A test stand, we found problems
with the LLRF control system,ysuspectingpg its stableness.
 Measured RF powers, Q0, Vc, etc. shown here are all corrected for
calorimetric powers and powers measured in the radiation shield.
 We have been improving the LLRF control system, with which D1‐
A is now running for input‐coupler conditioning stably.

5 We will perform Vc‐holding
5.
holding endurance tests (Vc( = 0.9 andd 0.8
MV/cav) for Cavity No.1 with the improved and stable LLRF
control system of the D1‐A test stand.
stand
6. Cavity No.1 is coming with the inner surfaces of theendplates electro‐polished.
electro‐polished→ To be high‐power tested this coming spring

40

Fin

Appendicespp42

Appendix A

43(T. Kageyama, MAC’11)

Appendix B:

Longitudinal HOM Impedance and CBI Thresholdat SuperKEKB‐LER(Simulation Results)
w/ S-cav
cav
w/o S
S-cav

τ=13ms13
for SuperKEKB-LER / 22 ARES cavities
with 3.6 A beam current

44Appendix C(T. Kageyama, MAC’11)

45

Appendix D:

A Set
S t off SiC Tiles
Til forf theth DR Cavity/HOM‐WG
C it /HOM WG or GBP

6 SiC Tiles

Copper Plate with a Cooling Channel(Y. Takeuchi)

SUS Frame for Welding
Cooling-Water Pipe Joint

46

ARES
Joint btwn C-cav and S-cav

Appendix E (1/3):
Cavity‐GBP Joint Structure
SUS

Weld Ring Gasket with Lip Sealing, like:“Welding  Disassembly ReWelding”
Possible Several Times

Finger-type RF shield- Successful experience at KEK/PF:

Be-Cu, @KEK/PF(Fixed with 16 M12 bolts)

Used in the Single-Bunch-Mode Operation- BeamB
current:
t 70 mA
A ((max.))- Bunch length: 24 mm
47Appendix E (2/3):
Reasons why we adopted such structure
for the Cavity‐GBP joint• Successful experience at KEKB‐MR/ARES (C‐cav and S‐cav) on
leakproof vacuum sealing during high power operation with heatd fdeformationti off theth cavityit• We do not need to disassemble the structure so often. (twice at
max from our experience at KEKBmax.
KEKB‐MR/ARES)
MR/ARES)– “WeldingDisassemblyReWelding” possible 3 times in the spec.

• Finger
Finger‐type
type RF shield– Measure against heat deformation of the cavity during high power
operation– Should be safe for low beam currents, such as this DR.
– Successful experience at KEK/PF.
– Negligible
N li ibl wakefieldk fi ld andd HOM heating
h ti (< 1W ffrom th
the simulationi l ti (next(page)))• x48

Appendix E (3/3): Results of the Simulation
Loss Factor[V/pC]

Loss Powerfrom the Loss Factor[W]

Without the Fingers

0.017

9.7

With the Fingers

0.00048

0.27
This loss power is negligible!!

For the DR Parameters:- Bunch Charge: 8nC- Bunch Length: 6.5mm- # of Bunches: 4/ring- Circumference:135.5m

49Starting DR commissioning with the two cavities:
GBP ((dummy)y)Total Vc (sepc.): 1.4MV

Appendix F
Total Vc (sepc.): 2MV

Install the 3rd Cavity if needed50Appendix G: Continuous Emission v.s. Vc
Taken on the last day of the HPT of Cavity No.0 (well-conditioned)
Using a highly-sensitive cameraIf we use a usual camera, almost no emission observed.
(Edited by Mikio Tanaka (Mitsubishi SC))The colors are difference between Vc<0.7MV and Vc>0.7MV.
51

Appendix H (1/2): Cavity (main body)Material: Highly-Pure Copper (C1011-C1)
except for the flanges, ports, GBPs, and HOM-WGs
Mirror symmetry except for the E-bends, tuner, and monitor ports.
Two input-coupler ports, one of which is to be used as a pumping port

(Along the beam axis)

110deg

70deg

R=150

R=150

Cross-section: 240mm x 28mm

150

340

Tuner Port (ICF20
03)

525

Input-Coupler or Pumping Port (ICF203)

556 +- 3
View Port(ICF70)(Cross-section perpendicular to the beam axis)
150

256

150 (Dimensions in mm)

52Appendix H (2/2): Cavity (Main Body)
240
220

ICF34

200

ICF203

30
R10
4-R10
R10

256

63.9

55°

110

10(Nose Cone)

161.8

20
00(Nose Conee Top)

260

340

304

280(Nose Cone Region)
R

R10

16

28

(Along the Beam Axis)

ICF203

120 2
120.2
ICF70

(Perpendicular to the Beam Axis)

ICF203

Appendix I: HOM‐WG Load
6 SiC tiles (=1set)20

12

Cross-section: 240 x 28
Material of the WG: SUS
HOM Absorber: SiC (Silicon Carbide) ceramics•Brazed on a copper plate•Water-cooled via the copper plate•Same
Same as used for the KEKB-MRs/ARESKEKB MRs/ARESPower Capability: 1.2kW/set(@1.3GHz)
Max. HOM Power absorbed: ~30W/WG
Max. Accl.-Mode Power absorbed: ~130W/WG (for Pwall=180kW)

HOM

Flange on thF
he loadFlangeon the E-b
bend

300

50

50

((Dimensions in mm))

550

54

Appendix J: GBP (btwn)
Material: SUS
4
4 sets of SiC tiles (same as used for the HOM-WGs)
HOM WGs)
Max. HOM Power absorbed: ~200W/GBP (incl. the loss factor)
Max. Accl.-Mode Power absorbed: ~100W/GBP (for Pwall=180kW)
Loss factor: ~0.2 [[V/pC]
p ] ((for zmm))(Dimensions in mm)

4-R10
4-R3
4
R3

544
340

45deg
4-R2

30

(Cross-section perpendicular to the beam axis)(Along the beam axis)

55

Appendix K: GBP (end)Material: SUS
4 sets of SiC tiles
Max.
Max. HOM Power absorbed: ~200W/GBP
200W/GBP (incl. the loss factor)
Max. Accl.-Mode Power: ~100W/GBP (for Pwall=180kW)
4-R10(Dimensions in mm)

544

4-R3

340

253

45deg
4-R2

30

HELICOFLEX flange(Cross-section perpendicular to the beam axis)(Along the beam axis)

56Appendix L: GBP(dummy)Material: SUS
No HOM absorbers
To be used for the two-cavity configuration
556

4-R10
(Dimensions in mm)

4-R3

340
30

(Cross-section perpendicular to the beam axis)(Along the beam axis)

57Appendix M (1/6)

RF Power Fluctuation ((1))~~ Fast ~~Klystron Output PowerPi k Field
PickupFi ld

Arbitrary Scale
A

Arbitraary Scalee

Pin measured in the D1 control room58

Appendix M (2/6)

High‐Powerg
Pickupp Antenna
Port2: Pickup Antenna:

Port1: Input Coupler(Assuming 0.1%
0 1% accuracy)

59

Appendix M (3/6)

RF Power Fluctuation ((2))

Recalibration Constants~~ Slow ~~Pini (corr) = cin
i x Pini (meas)Prefl(corr) = crefl x Prefl(meas)

Recalibrated for calorimetric powers andpowers measured in the radiation shield

60

Appendix M (4/6)

Measures toward the HPT of Cavity No
No.11(I) We will measure Pin and Prefl with power sensors directly connected to thedirectional coupler in the radiation shield,
then transmit the values via the LAN to the D1 control room in digital
digital.
(II) We will lay new coaxial cables from the radiation shield to the D1 control room
for the cavity pickup (used in the feedback) and reflection (used in the I/L)
I/L).

We will p
perform Vc-holding
g endurance tests
for Cavity No.1 with the improved environment.

61

(I) RF Power Measurements of Pin and Prefl close to the Cavity
in the Radiation Shield of D1‐A Test Stand The power sensors are directly connected to the directional coupler.
 The power meter is also put in the shield with its ethernet interface
connected to the control network
network.
Power Sensor
Ethernet Cableon the Control Network
WaveGuide (W-1500)

Appendix M (5/6)

Power Meter

Directional
CouplerThis is the current setup for coupler conditioningat D1-A test stand.
62

Appendix M (6/6) (II) Coaxial Cables:
Radiation Shield <‐> D1 Control Room
OLD

NEW

Laid ~30 years ago
~70m-long cables of 10D-WF-H50-S4
Total cable loss (meas.) : ~5.2dB (spec.: ~3.6dB)

Laid in Jan., 2013
91m-long cables of 10D-WFLEX-FR
Total cable loss (meas.) : 4.4dB (spec.: 5.5dB)

Above the ground High Accessibility

Under the ground Low Accessibility

63

Appendix N (1/2):
Longitudinal Impedance of the RF section:
and
d CBI
Estimated from Finite-Difference Time-Domain parallel computations of GdfidL CBI threshold for Total Vc: 1.4MV
with the PC cluster (256 cores & 512GB memory)G
Growthh TimeTi＞ 20ms20＞ 5ms (rad. damping time)64Appendix N (2/2) :Transverse Impedances of the RF section:
and
d CBI

Estimated from Finite-Difference Time-Domain parallel computations of GdfidL
CBI threshold for Total Vc: 1.4MV
with the PC cluster (256 cores & 512GB memory)(Tuner Position: 30mm inside)

Growth Time ＞ 30ms
＞ 10ms (rad. damping time)65Appendix O
Typicall cyclel time off RF conditioningd
off one couplerl includes:l d1) Setup & low‐level measurements : 2 days (net time: 8x2 = 16 hours),
2) Vacuum evacuation: 4‐5 days (about 100 hours), and
3) RF conditioning up to Pin=800 kW : 15 days (weekdays only, net time: 8x15 = 120 hours),

so that the cycle time is 1) + 2) + 3) + weekends = ~1 month.

66

EOF