REMARKABLE PRESSURE RISE AT PUMPING PORT IN J-PARC MAIN RING

Masahiko Uota #, Masayuki Shimamoto, Yoshihiro Sato, Yasuhiro Takeda, Yoichiro Hori, Yoshio Saito

KEK

1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan

Abstract In J-PARC MR synchrotron with high power beam operation, the remarkable and endless pressure-rise over 10-4 Pa

or more is found when a ion-pump of the ring turns off by accident or on purpose. This high pressure exceeds the normal pressure distribution of pump series and causes the beam loss by nuclear interaction. The outgassing rate depends on the existence of external magnet field at the pumping port, the initial pressure and the operating beam power. A minus potential synchronized with the operating cycle are found at the electrode in pumping port. The formation of electron cloud is considered to the pressure rise.

J-PARC MRイオンポンプ OFF時の顕著な圧力上昇

1. J-PARC 50GeV (MR)

3.0430GeV 92×1012 (145kW )

MR1600m

MR 0.5—0.6 m3/s (IP) in-vacuum

[1,2] 2010 1 35kW

IP #111( 1 ) 5 60kW

IP 26×10-7 Pa

1.2×10-6 Pa

10-3 Pa

MPS( 1 )

IP

IP 2

2. 2011 MR IP 2

MR 1 module 15 50.8m 24 module2010 IP 1.5

/module 34mmodule

IPdispersion

3-50BT

RCS

Abort Dump

WALL

Slow

Ext

ract

ion

Neutrino Beam Line RFRF

KM

1

KM

2,3

KM

4,5

SM

1,2

SM

31~

34

0 25 50 100m

ESS2

SMS3

SMS2

SMS1

ESS1

InjK

COL1

COL2

COL3

ABS

InjSM1,2

GV

GV

GV GV

GV

GV

GV

GV

GV

GV(A)

GV2

GV(HD)

GV(N)

GV

GVGV

GV

GV

GV

GV

GV

GV

GV1

GV3

GV4

IP2

IP3IG4CG

4

RP3

@M

W

IG3CG3RP2@MWIP1IG1CG1

IG2CG2RP1 IG5IP4IG6(NC)

PLUG1

IG8CG6RP6

IG7CG5@MW

IG9

IP11

IG10

CG

7

RP7

@M

RPM

RP

CG,RPIP13

IP12

RP

IP,IG013

IP,RP,IG015

RP

RP

IG005,CG,RP

IG006

CG,RPIG004@MRPM

IP,IG008

IP,IG012

IP,IG011_1

IPIP

IPIP

IP14

IP5

IP6

IP7

IP8

IP10

IP107

IP097

IP093

IP087_1IP_SLOWEXT

IP085

IPIPIPIP

IPIP

IP

IPIP

IPIP

IP111

IP116

IP121

IP125

IP130IP135IP139

IP144

IP146

IP148

IPIPIPIPIPIPIPIPIPIP IP150_1

IP

IP159

IP165

IP169

IP174

IP179

IP183

IP188

IP193

IP197

IP202

IP207

IP211

IP216

IP102IP021

IP025 IP028

IP042

IP056

IP

IP100

IP114

IP128

IP142

IP172

IP186

IP200

IP214

IP030 IP035 IP039

IP044

IP049

IP053

IP058

IP

IP

IP

IP074

IPが粗 : 最近接IPまで34mIPが密 : 最近接IPまで15～18m

Arc A

Arc BArc C

Insertion A

Insertion C

Inse

rtio

n B

粗密

粗

密

粗

密

粗

2011/1IP入口にシールド(パンチングメタル) 密

2011/1ループアンテナ

2011/1円盤電極

AB

B

Aʼ

A

Aʼ

2: MR (2011 3 ).

10

-7

10-6

10-5

10-4

10-3

Pre

ssur

e [P

a]

16:1505/11/10

16:30 16:45 17:00 17:15 17:30 17:45 18:00

dat

60

40

20

beam

pow

er [

kW]

IG_028p IG_042p

IG_049p MRPWRv

IP039&044 off bycontroller down

Beam off byMPS(BLM)

~1e-6 Pa incontinuous operation

exponentially(or more) rise

cont. op.resume

1: OFF-IP (2010 ). ____________________________________________ # masahiko.uota@kek.jp

Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan)

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IPIP

2010 463kW IP

10-4 Pa

12IP

IP2010 100kW140kW

10-6 Pa3 2009 2011 3

3Ti

IP

130mm

80cm

DC

3.

3.1

1—2 IP

A

A’

B

4: IP OFF .

2010 2

IP OFF10-4Pa ON

10-4Pa 2—3IP

OFF

2010/11—2011/1 95—110kW3

OFF (B-A ) 4 2

IP

1 ( )

1 ON/OFF

A, A’

68m3—10 10-4Pa

B

10-7

10-6

10-5

10-4

10-3

Pre

ssur

e [P

a]

IP002

——

——

IP004

Injsep2(2)—

——

—InjK

ick(2)C

ollimatorA

reaD

Kick(-2010/8)

IP013

IP015

IP021

IP025

IP030

IP035

IP039

IP044

IP049

IP053

IP058

IP063

IP067

IP072

IP074

ES

S1(2)

——

——

ES

S2(2)

IP078

IP079

SM

S1(2)

——

——

SM

S2(2)

IP087

IP093

IP097

IP102

IP107

IP111(2009/12)

IP116

IP121

IP125

IP130

IP135

IP139

IP144

RF

area1R

Farea2

IP150

——

—K

M1(2)

——

——

——

KM

2(2)K

M3(2)

——

——

KM

4(2)—

——

——

——

—K

M5(2)

SM

1(2)—

——

—S

M2(2)

IP157

IP159

IP165

IP169

IP174

IP179

IP183

IP188

IP193

IP197

IP202

IP207

IP211

IP216

Main Ring 1567.5m

QD

X216

QD

X016

QD

X072

QD

X088

QD

X144

QD

X160

QD

X216

Insertion A(116.1m)

Arc A(406.4m)

Arc BInsertion B Arc C

Insertion C

FX Septum 1, 2

FX K

icke

r 1-

5

SX S

eptu

m 1

, 2

Inj.Septum 2

ESS

1, 2

RF

disp. max without IP

disp. max with IP

Collimator Area

IP028(2010/8)

IP042(2010/8)

IP056(2010/8)

IP070(2010/8)

IP100(2010/8)

IP114(2010/8)

IP128(2010/8)

IP142(2010/8)

IP172(2010/8)

IP186(2010/8)

IP200(2010/8)

IP186(2010/8)

Dat

a m

issi

ng b

y no

ise

3: .

A 34m 34m 68m,

A’ 17m 17m 68m, 2

B 34m 17m 51m,

Proceedings of the 8th Annual Meeting of Particle Accelerator Society of Japan (August 1-3, 2011, Tsukuba, Japan)

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A, A’B

• A, A’ B •

•

1–2×10-6Pa • (

)

3.2

A, A’ B(68m 51m)

1.5

A A’ 21 ( 2 IP)

( 5a)Q

A’ 1B Q Bend

( 5b) 5a QBend (

)

• dispersion

• Q

( Q 3m D.S.)

• Q Bend

5: a) missing bend Q , b) Q Bend .

bellowsbellows

bellows

outer tube

inner tube

contact point

floated Be-Cu fingers

pumping

binding ring

Ion Gauge (back)

2 Electrodes(Floated)

to OSC

Ion Pump

bellows

Ion Gauge (back)

2 Electrodes(Floated)

to OSC

6:

4. #146 RF

( )30mm

( 6) IP

RF

dispersion 2 IP144 IP14814m IP146

29m

phase 1 turn7

bunch

BPM

7: ( : , : ).

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8: LPF & 8 shots

RC( 1k 1μF) 150Hz LPF8

1( 8)

9

LPF C(1s) decay

( )

300.5nC/μPa

120mm 10nC/μPaB-A

ON/OFF

5.

/

consistent 3

(OFF )

3

6.

7. LPF RF

[1] M. Uota, et al., “J-PARC MR

”, Proceedings of the 7th Annual Meeting of Particle Accelerator Society of Japan (August 4-6, 2010, Himeji, Japan), p721.

[2] M. Uota, et al., “VACUUM SURFACE SCRUBBING BY PROTON BEAM IN J-PARC MAIN RING”, Proceedings of IPAC’10, Kyoto, Japan, p3858.

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

Ele

ctro

de P

oten

tial [

mV

]

-2 -1 0 1 2Operation Cycle [s]

8times average 5e-7Pa +IGoff IGon, IPoff, 1.2e-6Pa IGoff, IPoff, 1.5e-6Pa IGon, IPoff, 2.1e-6Pa IGoff, IPoff, 2.6e-6Pa IGoff, IPoff, 4e-6Pa IGon, 2IPoff, 8e-6Pa NO BEAM, 2.2e-6Pa

BE

P3P2

P1

IGon, 2IPoff, 8e-6Pa

IGoff, IPoff, 4e-6Pa

IGon, IPoff, 2.1e-6Pa IGoff, IPoff, 2.6e-6Pa

IGoff, IPoff, 1.5e-6Pa

IGon, IPoff, 1.2e-6Pa

5e-7Pa +IGoff

NO BEAM, 2.2e-6Pa

2011.2.15-163.2s cycle, 136kW

next P1

next P2

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

Peak

Vol

tage

[m

V]

1086420Pressure [μPa]

NO BEAM

Peak Voltage vs Pressure

IP ONIG ON/OFF

IP OFF

9:

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