MR magnets and QCS
Y. Arimoto
12/13/2022 Accelerator Review Committee

Contents••MR magnets•

NLC•

Cooling water maintenance•AlignmentQCS•

Vacuum leak of QCS cryostat•

Magnetic eld variation

Summaryfi•

Non-linear collimatorNon-linear collimator (NLC) installation andmodification at Oho straight section
Installation of a new collimator that is less likely tocause Transverse Mode Couple Instability (TMCI)! Conventional collimato• Installing at the location where β function is large• But the narrow collimato⇒ Since βk is large, the threshold at which TMCI occurs
becomes low! Non-linear collimato• The nonlinear kick of the skew sextupole magnet increases
the beam size
• It enables to collimation of the beam at a small beta function.
• It makes the physical aperture of the collimator large⇒Since the βk becomes small, the threshold becomes highS. Nakamura
SuperKEKB Machine Parameters<latexit sha1_base64="sR0+T3cjYIT8xRCoFeRpaIb789c=">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</latexit>

Bunch current threshold at
which TMCI occurs

Ith / P

1ii kiK. Oide, 第7回SuperKEKBの長期運転プランに関する検討会(2021.05.14)

In SuperKEKB, the physical aperture of the vertical collimator isnarrower than that of the horizontal collimator, so the βk at thevertical collimator must be smaller to increase the TMCI threshold.

.

.

rrr.

.

第122回Bファクトリー計画推進委員会

4Non-linear collimator: Location•NLC will be constructed at OHO straight section.
IPTSUKUBA
Construction site ofnon-linear collimator

NIKKOOHOFUJIT. Ishibashi

Non-linear collimator: Construction

S. Nakamura← IP (Tsukuba)
HER(e-) →LER(e+) ←Skew sextupole magnet

New collimator (D05V1)• Take away these wiggler magnets.
Twenty double-pole magnets, ten single pole magnets, ten
half-pole magnets.
The weight of the power cable, which is removed withmagnets, is about 3000 kg.
• Relocation quadrupole magnets.
• Install a pair of new skew sextupole magnet.
• Install a new vertical collimator (D05V1).
Now we are working to remove the wiggler magnets.

Skew sextupole magnet

Wiggler magnets~40 mBefore the installation work started（Wiggler magnets）
S. Nakamura

7

Current status
S. Nakamura

Splitting work for vacuum pipe removal

Cooling water draining operation

第122回Bファクトリー計画推進委員会

8

S. Nakamura

第122回Bファクトリー計画推進委員会

9Additional magnet power supply for NLC
D5電源棟
QFWOP_5
QDWOP_6

QFWOP

QN6OP
QN8OP
QN5OP
QN7OP

QN3OP

QN1OP

QN2OP_2

QDWOP_2
Wiring changes due tothe NLC installation

S. Nakamura
第122回Bファクトリー計画推進委員会

SNAP_210

S. Nakamura

Place and routing of new power supply• Number of new power supplies: 10 unit
• Reuse of 4 strips of the existing 2 quadrupole electromagnetic
power supply system• A total of 16 new power cables will be installed• Quadrupole electromagnets are rated at 500• Skew sextupole electromagnets are rated at 600• 400 sq-1c cable to be installed

Candidate forplacement of the power
supply for NLC2 power supplies/rack.

AAss

第122回Bファクトリー計画推進委員会

11

Skew sextupole magnets for NLC• Two new sextupole magnets need to be produced for NLC.
• Since due to COVID-19, it takes more than ten months to
obtain a hollow conductor, if we purchase the new one, theskew sextupole magnets will not be ready for operation infall 2023.

• To be ready for the next operation• The iron yoke will be newly fabricated• The coil will be reused from the other sextupole magnets(SL0.3).
(We have a spare magnet and one set of spare coils.)• Magnets will be delivered in August 2023.

Drawing of magnets for NLC••

Bore radius: 56 m
Lamination Length: 300 mm  .

,m R. Ueki

Cooling water system for MR Magnet
・1750 water cooled magnets are installed in SuperKEKB tunnel
・Pure cooling water is supplied to these magnets at 8 location pump system.
・The routine maintenance is important to remove impurities and keep the system in good condition-Strainer cleaning once a mont
Cleaning flow paths of magnets low flow rat
Replace aging componentetc.
Example of impurities

A strainer just before a pump

Entrance of water hose of a magnet

・Thanks to the routine maintenances

R. Ueki. 

.

,ehs

no failure of magnet cooling water has occurred for 31 months since October 2019.

Tunnel level wrt IP (mm)Tunnel level variation every year wrt IP2018 Sept
2022 AugIP•

The tunnel level goes down about 5 mm from 2018 to 2022.

M. Masuzawa

Seasonal variation of tunnel levels
noitisoDate)mµ(lev
LeP

Seasonal variation of about ± 0.5 mm is observed

M. Masuzawa

QCS cryostat oscillation at earthquake• When earth quake happened, we observed oscillation signal with the gap sensors at QCS cryostat
gap sensor shows that the oscillation amplitude in the vertical direction is two times smaller than the horizontal• Thedirection.

M. Masuzawa

QCSVacuum leak of QCS-R cryostat

Vacuum pressure of QCS cryostats

Degradation of vacuum pressure of QCS-R
Aug/3/2021

An additional TMP
removed
2 TMPs added

Pressure (Pa)QCS: Room temperature

Time (hours)
Leak rate: 4 ×10-4 Pa m3/s

He Leak check performed at LS1今回のリーク試験注意事項（LS1）••

Sep/2022

OリングところにHe-trapを作る–•

We made He-traps around O-rings.

•Heガスを付いている時間（＞5分）–•

We waited 5 minutes to see if thevacuum level changed.

•クライオスタットのボリュームが大きいのでHeDetectorまで時間がかかる•

リークdetectorの排気能力•

QCS-LとRの比較（Oリングの透過率の確認）

We performed this leak check in

Support rods cups: 16
Vacuum vessels, O-ring: 3+1
BPM windows: 4+2

cooperate with QCS and the vacuum
group.
•Heガスが空気より軽くて直ぐに逃げる

He-trap for beam pipes

We found a leak at the service
cryostat.
We will open the service cryostat andrepair at the end of this scal year.
2022/10fi•Helium Leak Test of QCS Cryostat

13by Z. Zong

Leak area of QCS-R
Service cryostat

Transfer tube: no Leak !

3

Leak rate (Pa*m /s)

Magnet cryostat: no Leak !

Leak !

Trend of He leak rate

5E-05

by Z. Zong

1E-05 16:02~ GHe to
1E-06

Service cryostat
O-ring at the middle

2 min2x10-5 Pa m3/s
1E-07
1E-08
1E-09

16:00

Vacuum level:
1.9E-3 Pa Pump guage
4.1E-3 Pa cryos. guage

16:10

16:20

Drift of vertical model tune

Model tune variation (Nov/2021)(a)

LER Current
HER Current

(b)

(c)

Tune
Model Tune

Tune
Model Tune

Tune
Model Tune

Earth quake

Energy scan

Energy scan

Energy scan

Energy scan

Restarted All QCS
Ramp up QCS current

Ramp down QCS current

Flux creep•The long-term drift of the magnetic eld on the accelerator magnets has beenreported by Fermilab, DESY, BNL.

•They mention that the ux creep is the cause of the drift.

•The ux creep is a fundamental phenomenon on type II superconductors (SC).

••The pinning center in the SC moves, and some pins go out of the SC.

•This reduces the magnetization in the SC.

The time dependence is given by:

B(t) = a log t + bfiflfl<latexit sha1_base64="Q0daza6LMUaJEPd3UQcENJySLzI=">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</latexit>

Time variation of B3 component observed atthe dipole magnet of DESY

Flux creep•

The long-term drift of the magnetic eld on the accelerator magnets has beenreported by Fermilab, DESY, BNL.

•They mention that the ux creep is the cause of the drift.

•The ux creep is a fundamental phenomenon on type II superconductors (SC).

••The pinning center in the SC moves, and some pins go out of the SC.

•This reduces the magnetization in the SC.

The time dependence is given by:

B(t) = a log t + b fifl

fl<latexit sha1_base64="Q0daza6LMUaJEPd3UQcENJySLzI=">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</latexit>

Long-term measurement of
quadrupole eld•

Jul/2022 - Mar/2022•

Quadrupole eld and multipoles weremeasured with the harmonic coil.

QC1P R&D magnet

QC1E Prototype magnet

Setup

Transfer tube for liquid helium

Shaft forHarmoniccoil

1000 L LHe Dewer

Liquid helium

Harmonic-coil shaft

Quadrupole
magnetHarmoniccoilfifiCryostat

Vertical cryostat•We observed the variation of quadrupole
component. They vary with a function of log(t).

•It indicates the variation caused by the ux creep.

•The time dependence of the variation depends onthe excitation pattern.

•∆R(t)
C2(t)/C0 -1

Measurement results: QC1P−3×100.1

QC1P R&D01638A→1600A−0.10A→1600A−0.2

The variation is large if we set the current in theup-ramp direction.
•−0.3

The quadrupole components of QC1P wereSolenoid on

varied by 3x10-4 in 6 hours−0.4
If we set the current in the down-ramp direction,
we can reduce the time variation of thequadrupole eld less than 0.5x10-4.

−0.5 210310410

flt (s)fi•Up ramp
Up rampDown ramp

•

•

•

When we set the current in the up
ramp direction, quadrupole component
increased by 1x10-4 in 6 hours.

∆R(t)C2(t)/C0 -1

Measurement results: QC1E−3×100.1

QC1E Prototype

0−0.1

The variation is almost zero when weset the current in the down ramp
direction.

−0.2

The variation is smaller than QC1P.

−0.3

−0.4

−0.5
210Up ramp
Up rampDown ramp3104

10t (s)••∆ νyModel tune with down-ramp
on LER
After this measurement, we set the currentof the QCS in the down-ramp direction.

Model tune up ramp
Model tune down ramp
Up rampUp rampDown ramp

0.01

LER
0Magnetic−0.01 measurement

After the beam-induced quench of QC1(R/L)P on Jun/9/2022, we restarted themagnets in the down-ramp direction andobserved no signi cant drift of the verticalmodel tune for LER.

Model tune
with up-ramp−0.02

Initialization pattern of QC1P

May/10/2021−0.03
Model tune
with down-ramp

1800
1600
1400

2.5%

1200
1000

Jun/9/2022

800
600

−0.05

400
200
0

08:30

08:40

08:50

fi Time 

I (A)

−0.04

09:00

310

410

510t (s)Summary•

Installation work of NLC is underway•

Thanks to routine maintenance, we have had no failure in cooling water since2019.

•Tunnel level survey shows that the ring goes down 5 mm from 2018 andseasonal level variation was about ±0.5 mm.

QCS•

We found the leak at the service cryostat of QCS-R. We will repair this at end of
this scal year.

•We con rmed that the magnetic eld of the quadrupole magnet varied 3x10-4
by 6 hours. We can reduce the drift by setting the current with down ramping.
fifi•MR Magnetfi•