Present Status ofVacuum System Upgrade forSuperKEKB
Y. Suetsugu
for KEKB Vacuum GroupOutlines of vacuum system design
Production
Design for remained parts
Installation
Summary*Details about the pre-installation work and the beam collimator design arepresented next by Shibata-san and Ishibashi-san, respectively.
*Vacuum system around IP is presented by Kanazawa-san.
2013/3/4

KEKB Review 20131

Outlines of vacuum system design
The design basically continues the policy in KEKB,
introducing new ideas developed during the operation.
 Point 1: Ultra-high vacuumKeep small emittance, Reduce background noise to detector,
Avoid ion instability [HER] Realize vacuum pressure on the order of 10-7 Pa with beam
P(CO)=1~2x10-7 PaDistributed pumping system utilizing NEG strips
Pumping speed: 0.14 m3/s/m for CO after activation.

Point 2: Low beam impedance
Keep small beam emittance andshort bunch length, Avoid single
and multi-bunch instabilities
 Beam pipes with antechambers.
 Low impedance components,
Step-less connection flange,
New bellows chambers,
gate valves, collimators
2013/3/4

KEKB Review 2013

SR2

Outlines of vacuum system designPoint 3: Suppression of Electron cloud effect [LER]
Avoid emittance growth, beam size blow up
 Solenoid field, TiN coating And new technique:
Clearing electrode,
Grooved surface
Electrode

GroovePoint 4: Utilization of KEKB resources

Reuse vacuum components in KEKB as much as possible
 Basically, Infrastructures, such as electric lines, cooling waterpipes, are basically reused, after maintenance.
 Modernize the control system in anticipation of next 10 years
operation



Basic design had almost finished, and the production ofvarious components has started in full swing since last
fiscal year.
2013/3/4

KEKB Review 20133

Production: Beam pipe

LER wiggler sections and their downstream region:
already delivered
Nikko and Oho (LER and HER) Copper beam pipes with antechambers
Oxygen free copper (c1011)
 Type-S： 122, 377 m
 Type-Q: 47, 76 m
Type-S in LER wiggler magnets has
two clearing electrodes.
Type-Q

Type-SElectrode

2013/3/4

KEKB Review 20134

Production: Beam pipeArc sections: already deliveredAluminum-alloy beam pipes with antechambers
Formed with a extrusion method (A6063)
 Aluminum-alloy flange (A2219)
Type-S: 271, 754 m
Type-Q: 310, 622 m






With BPM block

Type-B: 106, 485 m
(1861 m in total)

R=74.7 m, With groove structures

Type-Q

Type-B

Aluminum-alloy flange

BPM blockType-S

2013/3/4

GrooveKEKB Review 20135

Production: Beam pipeBeam pipes for other sections


HER symmetry section: already delivered

LER Oho RF cavity section:
already delivered

Antechamber and circular (taper)
Aluminum alloy, 16, 38 m

Beam monitor section: in production
Circular, Copper, 4, 12m

Rotatable SX section: in productionRace track, Copper, 24, 35 m

Circular, Racetrack, Copper, 13, 16 m

Fuji cross point: in productionRace track, Aluminum alloy
7 m [LER]: 11 m [HER]

Beam pipes of ~2400m (85%) will be prepared this fiscal year
2013/3/4

KEKB Review 2013

6

Production: Pump
ScreenGetter pump: Almost delivered

Main: Three layers of NEG strips ST707 3D

Activated by micro-heaters (sheath heaters)
inserted between strips

Installed into an antechamberScreens between pump and beam

3 layer NEG strips

NEG strips, Heaters, transformer,
Feed-though were already delivered.
 Aux: Ion pumps (reuse)Installation of NEG
NEG strip

Screen(Φ4mm、6mmpitch)Feed-through2013/3/4

Feedthrough

KEKB Review 20137

Production: Components
Bellows chambers: Almost delivered
With Comb-type RF shield, Fit to antechamber cross section
 Copper: Mainly for Wiggler, Straight, HER arc
 Aluminum alloy: Mainly for LER Arc
 Last year: ~930, this year ~300 (including some of LC region)
Copper bellows chamber

Aluminum alloy bellows chamber

Inside2013/3/4

InsideKEKB Review 20138

Production: Components
Gate valves: Almost delivered
With comb-type RF shield Fit to antechamber cross section
 Stainless steel (copper shield)RF shield

Other components: Being produced in series

Metal gaskets

For special connection flange Copper and aluminum alloy

Metal pipes for cooling water,compressed air
 Various types of connectors, etc.


Metal gaskets

Gate valve

Control instruments: Being upgraded in seriesControl systemMonitoring system

Replace CAMAC system to advanced one based on Ethernet.
Increase monitoring system, improve data recording system

Pump system (NEG activation system)

2013/3/4

KEKB Review 2013

9

Design: Remained

Beam pipes for local correction section (LER and HER)
Aperture was fixed.
 Basically the same design to the arc section
 Use Copper at upstream side considering
back ground of the detector
 Will be produced next fiscal year

HER ~270 m, LER ~270 m
 Bellows chambers are in production.
50x44 ellipse+ Antechambers

f80+ Antechambers

f90+ Antechambers
The same to Arc2013/3/4

KEKB Review 201310

Design: Remained

Beam pipes for the beam injection andabort system regions, and SR monitorregions (Fuji straight section)
The design will be fixed soon.
 Components required for the Phase-1
will be produced next year and the year
after next.
SR monitor region ~30 m [LER, HER] Injection and abort region ~ 30 m [LER, HER]
2013/3/4

KEKB Review 201311

Installation: preparation

Pre-installation work is now in progress

Workflow before installation

Package

Delivery
Clean room

Storage
Inside check

LER
Assembling

Clean roomHERPre-baking
TiN coating
BakingAssembling(pumps)
BakingPresented byShibata-sanStorage

Storage(Filled with N2)
Installation
2013/3/4

KEKB Review 201312

Preparation before installation
Some problems found during pre-installation work
Mold and rust in packages (~20 %)→Open packages ASAP.
 Cracks at welding lines (3 pipes) ,Bending at welding line (1)→ Change in our assembly and handling processes
 Scratches on the reference surface of BPM blocks (~90%)→ Polishing Vacuum leak at a welding line (1 pipe)→ Repaired by extra welding Contamination, dust and particles inside (~80%)→ Removed or wiped with alcohol in the assembling process Burr inside the holes for BPM electrodes (~60 %)→ Grind and removed in the checking process Damage of screw holes (4 pipes)→ Insertion of Helicoil


Make effective and timely responses to each case2013/3/4

KEKB Review 201313

Installation


Installation for wiggler sections has just started
Installation for Oho wiggler sections has finished2013/3/4

KEKB Review 201314

Installation


Installation for arc sections will start soon (in June?)
Supports are previously delivered in the tunnel.
 Some beam pipes were installed for test.
Type-S

Type-B

2013/3/4

Type-QKEKB Review 201315

Installation
Rough schedule

2013/3/4

KEKB Review 201316

SummaryProduction of vacuum components and purchase of
instruments for control system etc. have started in fullswing since last fiscal year.
Designs and R&Ds for the remaining sections (Local
correction section, etc., ~15 % of the total) and beamcollimator are in progress.
Pre-installation work, that is, TiN coating, Baking of
beam pipes are undergoing.
Installation of the beam pipes into the tunnel has juststarted from the wiggler sections. The installation
continues coordinating with other hardware works.
Thank you for the cooperation!
2013/3/4

KEKB Review 201317

Back up2013/3/4

KEKB Review 201318

Average pressure in arc


1m beam pipe (with TiN coating)
Thermal gas desorption rate (filled by 25℃ air)
– Qth = 7.77x10-9x5.4x10-1=4.2x10-9 Pa m3/s/m (After 60hourspumping)Average photon density (3.6 A):– LER: 5.3x1018 photons/s/m

If η = 1x10-6 [molecules/photon]– Qpsd= 2.2x10-8 Pa m3/s/mFor the effective pumping speed of 0.1 m3s-1m(After activation of NEG),
P = Q/S = 2.2x10-7 Pa

2013/3/4

KEKB Review 201319

Loss factors
Loss factors and kick factors for main components
2011/2/1 末次
Component

Resistive wall

Loss factor [V/C] Number of items
AlCu

Pumping port
Flange connection
Bellows
Gate valve
SR maskMovable mask
Taper
BPM
BxB FB BPM
FB kicker
IP chamber
GrooveGroove (RW x 0.14)*
Clearing ElectrodeCle Ele (RW-W)**
Cavity (ARES)
Total
Al

1.14E+09
8.22E+08
3.65E+02
1.45E+07
2.00E+09
3.00E+09
1.82E-03
1.00E+11
3.83E+08
1.63E+08
5.90E+08
5.01E+11
8.00E+08
1.00E+08
1.60E+08
2.00E+08
8.70E+08
4.35E+11* RW 50%増し x 80/(90*π)** タングステン 40mm分

2013/3/4

3000 [m]3000 [m]3000 [m]2000
900
401000
8 ?
100
450
10
11550 [m]550 [m]160 [m]160 [m]18

KEKB Review 2013

Loss factor(total) [V/pC]
3.42
1.10E-06
0.03
1.80
0.12
1.82E-120.80
3.83E-02
0.07
5.90E-030.50
8.00E-04
5.50E-02
8.77E-02
3.20E-02
1.39E-01
7.83
14.9 +α

Kick factor(total) [V/pC/m]

35.00

˜1000

2.50?
5.50
27.00
1.20

20

Countermeasures against Electron Cloud

Summary of countermeasures

Sections

L [m]

L [ %]Countermeasure

Material

Total

3016

100

Drift space (arc)1629 m54

TiN coating + Solenoid

Al or Cu

Steering mag.

316 m

10

TiN coating + Solenoid

Al or Cu

Bending mag.

519 m

17

TiN coating + Grooved surface

Al or Cu

Wiggler mag.

154 m

5Clearing Electrode

Q & SX mag.

254 m9TiN coating

Al or Cu

RF section

124 m

4

(TiN coating +) SolenoidCu

IR section

20 m0.7(TiN coating +) Solenoid

Al or Cu

NewCu

Electron density less than 1.0×1011 e-/m3 is expected.

2013/3/4

KEKB Review 201321