MR Magnets
Shu Nakamura, Ryuichi Ueki, Masashi Furusawa,
Yasunobu Ohsawa, Mika Masuzawa

2024/3/26

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Contents• Skew sextupole magnets for non-linear collimator• New power supplies• IR restoration• Some failures in the power supply• Summary

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Skew sextupole magnets for
non-linear collimator

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Production skew sextupole magnets

R. Ueki• Since obtaining a hollow conductor took more than ten months, the skew sextupolemagnets would not be ready for operation in fall 2023 if new coils were fabricated.
• The steel yokes were newly fabricated; one set of coils was reused from a spare sextupole
magnet (SL300), and another set was used from spare coils.
• The sextupole magnets were delivered at the end of August.
• Magnetic field measurement was done in the first week of September.
• Next week, the skew sextupole magnets were installed in the beamline.

Luminated iron yokes
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Sextupole magnets for NLC

Drawing4

Magnetic field measurement of skew sextupole magnets

R. Ueki• The operation current is 227 A.
• The difference between each magnet’s value and the average value in B3L isabout 2×10-4.
The pair of skew sextupole magnets are driven by the same power supply,
so the difference in B3L appears as it is.
However, the difference is acceptable.

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5• Each skew sextupole magnet has trim coils, and the trim coils were connected to generate a skew
quadrupole field.
• B2L sensitivity depends on the main sextupole coil current due to the saturation of the iron yoke.

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Correction coil excitation curve

R. Ueki6

R. UekiWorks in Oho straight section during LS1

Processing baseplate

Installation beam chamber
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Production and alignment new baseplate

Alignment of Q-mag

Installation of SNAP

Processing Q-mag standAlignment and survey
7New Power supplies

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Magnets and power supplies configuration
Two power supplies drove 5 or 6 quadruple magnets, respectively.

D5BeforeQFWOP_5

QDWOP_6← IP (Tsukuba)
After

QFWOP

QN8OP

QN6OP
QN5OP
QN7OP

QDWOP_2

One power supply drives one or two magnets.
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QN3OP

QN1OP

QN2OP_2

SNAP_29Power supplies arrangement
Ten power supplies for Q and skew sextupole magnet are needed.
Two small PSs for the trim coil are needed.

Jan. 2024

QDWOP_2(reuse)

Oct. 2024(Plan)QFWOP(reuse)

QN1OP D5-3-15

QN1OP D5-3-15

QN2OP_2

QN3OP D5-3-16

QKSNAP1(D5-5-10-11)
QKSNAP2(D5-5-10-12)

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QN5OP D5-3-17
QN6OP
QN7OP D5-3-18
QN8OP

D5-3-13

SNAP_2(w/o polarity changer)

D5-3-14

QN2OP_2

QN3OP D5-3-16

QKSNAP1(D5-5-10-11)
QKSNAP2(D5-5-10-12)

QN5OP D5-3-17QN6OP
QN7OP D5-3-18
QN8OP

D5-3-13
D5-3-14

SNAP_2(with polarity changer)

QDWOP_2
QFWOP10Power supplies arrangement(cont.)

Jan. 2024

QDWOP_2(reuse)

QFWOP(reuse)

QN1OP D5-3-15
QN3OP D5-3-16

QKSNAP1(D5-5-10-11)
QKSNAP2(D5-5-10-12)

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QN5OP D5-3-17
QN6OP
QN7OP D5-3-18
QN8OP

D5-3-13

SNAP_2(w/o polarity changer)

D5-3-14

QN2OP_2

Production of 10 (+ spare) new power supplies has started.
Contract signed in April 2022.
Delivery was scheduled for March 2023.
However, due to COVID-19 and other factors, deliverywithin LS1 (by summer 2023) was impossible.
As a result, the newly manufactured power supplies weredelivered in March 2024.
The required number of power supplies was secured byreusing PSs, borrowing spare PS in DR, and restarting
power supplies that had been stored for parts removal.
(Thereby ensuring the required number of units plus one.)
However, in October 2023, a PF's power supply failed, anda power supply with a compatible rated output was lent.
Thus, we are currently operating without a spare PS.
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Power supplies arrangement(cont.)
Skew sextupole magnets need to change the polarity.
A power supply with a polarity changer has to be used.
However, the alternative power supply does not havethe polarity changer, so an extension cable is used.

The installation of the
newly manufactured
power supplies will be
heldduringtheshutdown
inthesummer of 2024.
Ready for the power
supply arrangementchange, the power
cables were wired at
an extra length.
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Oct. 2024(Plan)

QN1OP D5-3-15

QN2OP_2

QN3OP D5-3-16

QKSNAP1(D5-5-10-11)
QKSNAP2(D5-5-10-12)

QN5OP D5-3-17
QN6OP
QN7OP D5-3-18
QN8OP

D5-3-13
D5-3-14

SNAP_2(with polarity changer)

QDWOP_2
QFWOP12

Works in D5 power supply building

Delivery and storage the power supplies.

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Power cable connection.

Reinforcement with steel to install the racks over the cable pits.

Additional breakers were added to the distribution13board.

IR restoration

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R. UekiWorks in Tsukuba straight section during LS1

QCSL moving forward

QCSR moving forward

Alignment of magnets
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Magnets restoration

Survey of magnets at L and R side15

R. UekiFirst collision tuning (Feb. 19)
The difference between both beam was 85 um.

iBump vertical offset (HER) 15 um*SAD coordination

LER local bump -100 um

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Some failures in the power supply

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Unintended interlock triggering
CH2
CH3

CH7

CH4

After these parts were replaced, this phenomenon no longer
occurs.

CH8

CH1

CH6

CH1 : Thermoswitch (Open at high temp.)
CH2,3 : AC current (1A/1mV)
CH4 : Drive voltage of Contactor#2(2R) (10V/1V, AC100V)
CH5 : DC voltage (500V/1V)
CH6 : Relay(5R) (Close when voltage is applied.)
Ch7 : Drive voltage of Contactor#1(1R) (10V/1V, AC100V)
CH8 : Drive voltage of the relay(5R) (10V/1V, AC100V)
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CH5

The power supply(SD3ORE_2) frequently mis-detectedinterlocks(AC Over Current) and stopped.
The beam operation was also stopped several times.

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Unintended current reduction

The power supply(QFROE_4) sometimes unintentionally reduces
the output current.
The only interlock the power supply displays is “Tracking”, but theoutput current is zero A.
A malfunction due to noise in the control circuit is suspected.
The control power supply was replaced, but the problem recurred.
Other measures are under consideration.

Tracking(Trig)
Control PS
U202-1
U201-1
Output Voltage
Output Current
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Summary• Skew sextupole magnets fabricated with new yokes and old coils
performed properly and were installed in the beamline.
• New power supplies were not available in time due to COVID-19
and other factors, so a spare power supply and old power
supplies were reconditioned to cover the cost.
• New power supplies were delivered this March and will be
installed next summer.
• IR restoration is good.
• Some power supplies have problems.
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