Development of Pulse Magnets
for Injection and Abort Systems

T. Mori (KEK)SuperKEKB Review
Mar. 4, 2014

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Construction Schedule Phase 1
 The new HER injection/abort system is installedThis is urgent issue & main topic of this talk

 The KEKB LER injection/abort system is preserved

DR is not ready at the beginning of Phase 1
Emittance is large; new LER system doesn’t work well for Phase 1

The LER current must be low to protect the abort window (< 500mA)

 Phase 2 The new LER injection/abort system is installed

DR is ON
 New LER chambers have smaller apertures than those of KEKB

They should be installed at the same time not to make cavity structures
New injection channel can’t be used for large emittance beam of Phase 1

2

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

3

List of BT Pulsed Magnets
MR-BTInjection

DR-BT

AbortInjection

HER

LER

H-kicker

6(3+3)

6(3+3)

412(1+1)

V-kicker--

11-

SeptumQuad

4-

HER

Extraction

2--LER-

12-

5 horizontal kickers for HER abort considered

1Pulse uniformity problem (shown in later slides)

1-Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

MR INJECTION

4

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

5Method & Parameters 2 candidates for HER

Baseline: betatron injection; same as KEKB Backup: synchrotron injection
 Injection system:

2 kicker systems to make injection bump (𝜋 phase advance) Kicker pulse: 2μs
 kicker pulse height fluctuation affecting the height of the bump: 1mm
 Effective septum width: 3.5mm (KEKB: 5mm)
Including non-uniform field region

Totally 4.5mm gap required by hardware Injection parameters are determinedaccording to ring & Linac parameters

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

6Parameters for Betatron Injection
 Required ring aperture for beam(2.5𝜎𝑥𝐼 ) injection is calculated asfunction of 𝛽𝑥𝐼Ring parameters
ParameterValue𝛼𝑥𝑅 = 0 is assumed
 𝛽𝑥𝐼 is determined at minimum ring aperture𝛽𝑥𝑅 = 40 m

𝛽𝑥𝑅 = 80 m
𝛽𝑥𝑅 = 100 m
𝛽𝑥𝐼 = 15.3 m

𝛼𝑥𝑅

7.93

𝛽𝑥𝑅

100m

𝜀𝑥𝑅

4.6 × 10−9m

𝜀𝑥𝐼

1.46 × 10−9 m

Injection parameters
Parameter Value
Δ𝑥7.8mmΔ𝑥′-0.62mrad

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

7

Betatron Injection Orbit
Center of beam duct

Injection param. ValueStored beam orbit
Duct inner wall

Septum
QI4E
Injected beam orbit

Partition wall ofinj. channel BPM(2mmt assumed)

Kicker height

28.5mmSlope angle−1.88mrad

𝐾1 (QI4E)0.1498

Height at QI4E

29.5mm

3𝜎𝑥𝑅

2.0mm

Δ𝑥7.8mmΔ𝑥′−0.62mrad

2.5𝜎𝑥𝐼0.37mm

We plan to install BPM on injection channel
 Increase of 𝐾1 QI4E increases the risk of wall hit


Betatron injection orbit can be designedwith current HER optics & hardware designableSynchrotron injection orbit also designed; almost same as betatron injection

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

8Septum Magnet Prototype

MR beam duct mockup(SUS430)
HERMagnetLER

Septum conductor width1mmEffective septum width

3.5mm

Gap8mmCore length

1m790mm

Pickup coil
0.5mm Si-steel sheet

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

9Field Measurement

10Gauss

MR ductCore Field profile with SUS430 duct is fine
 Leakage field sufficiently suppressed Necessary and sufficient design

 Simulation study for shim shape on goingMar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Power Supply for Septum
Inverter (IGBT)HV unit

De-Qing unit

DCcondenser
High precision
auxiliary charger



Main discharging circuit

Upgrade for SuperKEKB
Thyristor  Inverter (IGBT) Transistor  De-Qing unitControlled charge timing; double trigger driven

High precision auxiliary charger introduced

Current R&D issuePulse stability is not perfect:fluctuation > 1 × 10−3 seen in beginning 1-2 seconds
 De-Qing drift?
10Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

11Kickers for MR Injection

Magnets and power supplies will be reusedIssues


Thyratrons (1 thyratron/kicker)
KEKB type(EEV CX1154C) is expected to be exchanged every year with 25Hz injection
 Long lifetime type(EEV CX1826A) (is already installed in HER for test)
6-year achieved in KEKB, CX1154C lifetime in KEKB: 3-year with 5 – 10Hz continuous inj.
Demerit: price × 2
Another candidates

Replaced by semiconductor device
Spec. of MR injection kickers(Si thyristor, solid state thyratron, etc?)
TypeWindow frame
Pulse compression circuit (Rise time 5μs  1μs)
(Standard thylistors + saturable inductance)
CoreFerriteBeam chambers

No upgrade planned for Phase 1
 HERLERHeat generation on fringe part is possible
 Cu or Cu-coated kovar fringe is considered

Max voltage

32kV

Max current

2kA

Pulse shape

Half sine

Pulse width~2μs

3 chambers are planned to be exchanged for Phase 2

Waveform shaping circuit
Radiation tolerance unknown Placed under the kicker magnet
T. Mimashi

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

MR ABORT12

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Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Abort Kickers
Magnet

Newly designed & constructed

Ceramic beam camber


HER
Single ceramic (hollow type ceramic for water channel)
 Sleeve: kovar + 100μm Cu coat
 Problem: Ti wire evaporation coating failed
 Sputtering system constructed for 5μm Ti coat




LER
Double ceramic tube
 Sleeve: Cu
 Problem: many vacuum leaks during fabrication
 Sleeve structure changed

Entire Ti coated inner wall surface
Selected by the achievement on KEKB Stripped coat with high current beam is not trivialPower supplyPulse shaping issue
 Radiation hardness of pulse transformer


13

Kicker Magnet Construction

T. Mimashi

Ceramic Chamber
HERLER

KEKB

0.29kW

0.56kW

SuperKEKB

1.8kW

2.7kW

T. Mimashi

No local heating observed

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Sputtering System Parameter tuning Current rate

60hours/chamber
 𝐵 = 160Gauss 𝑉 ≅ 300V
 𝐼 = 300mA

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Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Power Supply Circuit

Placed under kicker magnet

 Issue Radiation hardness problem

 200mm polyethylene for neutron reduction
 7mm Pb shield17

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201418

Output Current of Power Supply
Inductance 4.5μH/165Ω+940pF
Voltage 39.3kV(W/ additional inductance)
Rise time (150ns)
Kicking beams out (10μs)

Peak 1750Ap(103%)
Flat 1700A(100%)
Rise time (2%-90%): 150ns
 Sufficient(500A/div,5μs/div)
10μs-flat: 8.8% Drop (it is not fatal)
 1 − 2mm shift on abort window Target: <5%Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

DR INJECTION & EXTRACTION

19

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201420

DR Injection & Extraction Arrangements

Extraction

Injection

SeptumSeptumMar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

DR Injection & Extraction Septa
Injection

Extraction

Deflection angle (mrad)

80

103

No. of magnet

1

1

Field strength (T)

0.36

0.47

Type

Eddy-current

Eddy-current

Aperture (mm)70(H)x24(V)

98(H)x30(V)Core length (mm)800800Coil turns

12Septum thickness (mm)

2.5

2.5

Waveform

Full-sine

Full-sine

Pulse width (μs)

300

300

Peak Current (A)

8000

5700

Max repetition rate (Hz)5050

Stability

<1E-3

<1E-4

In-vacuum

Out-vacuum
w/ ceramic duct
Injection septum

Ceramic duct for extraction septum

RF system near Ext. septum requires pressure < 10−7 Pa
 Out vacuum septum for extraction
Power supplies are same type as MR septa

M. Tawada

21

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

22

Summary of Remaining R&D Issues
 MR injection
 Septum

Stability of power supply
 Shim shape study Kicker

Thyratron lifetime issue: long life type is planned to be used
 Radiation tolerance for pulse shaping circuit MR abort
 Ceramic chamber: Ti sputtering Power supply: pulse shaping & radiation hardness

 DR injection/extraction
 SeptumDesign KickerPower supply R&D

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Thank you for your attention.

23

Mar. 4, 2014

BACKUP

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201424

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Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

MR INJECTION

25

Need for synchrotron injection
 Very low survival rate with betatron injection into HER is expected If offset ⊿𝑥 from IP for betatron oscillation,
 Kicked vertically by beam-beam force from the colliding beam
Tracking example with beam-beam interaction

𝑒+𝑒−IP

Offsetinteraction*
Injected oscillating beam

* Finite 𝑦-amplitude⟹ Large beam-beam kick∵ Hour-glass effect

Survive: 24%
Y. Ohnishi

 Synchrotron oscillation ⇒ no offset ⊿𝑥 (∵ 𝜂 ∗ = 0)

Synchrotron injection (as a backup option of betatron inj.)
Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Mar. 4, 2014

26

Dispersion & Momentum spread Dispersion by matching 𝜂 = −1.6 m
 𝜀𝑥 = 4.6 nm

𝑒 − Beam

Injection point Momentum spread 𝜎𝛿I = 0.1 % is assumed
Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Mar. 4, 201427

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Development of Pulse Magnets for Injection and Abort Systems, T.
Mori, MAC2014

28

Synchrotron injection orbitAlmost same as betatron injection case, only slightly tighter
Injection param. Value
Kicker height

29mm

Slope angle−1.89mrad

𝐾1 (QI4E)

0.1437Height at QI4E

30mm

3𝜎𝑥𝑅

1.5mm

Δ𝑥

7.2mm

Δ𝑥′

−0.52mrad

Synchrotron injection orbit can also be designed

Acceptance for Synchrotron Injection☆Synchrotron injection is intended to avoid stored beam blow up by injection beam
Schematic view of KEKB HER septum
Main ring

11mm

Septum Magnet

Cu

B⨀⨀

CoreCuSi-steelsheet × 2𝑤eff⊿𝑋𝑤eff ~ 5[mm](KEKB)SuperKEKB parameters• 𝛽𝑅 = 60[m]• 𝜀𝑅 = 4.6[nm]• 𝜎𝛿𝑅 = 0.059[%]• 𝑛𝑅 = 3.0• 𝛽𝐼 = 20[m]• 𝜀𝐼 = 1.46[nm]• 𝜎𝛿𝐼 = 0.1[%]• 𝑛𝐼 = 2.5•• ⊿𝑋 = 𝜂𝛿0 = 𝑛𝐼 𝛽𝐼 𝜀𝐼 + (𝜂𝐼 𝜎𝛿𝐼 )2 + 𝑤eff + 𝑛𝑅 𝛽𝑅 𝜀𝑅 + (𝜂𝜎𝛿𝑅 )2• 𝛿0 = (𝑝𝐼 − 𝑝𝑅 ) 𝑝𝑅
• 𝛿0 + 2𝜎𝛿𝐼 = 0.65[%] (by Y. Ohnishi)• 𝜂 = −1.6[m] (Achieved, sofar) of Pulse Magnets forDevelopment
Mar. 4, 2014

Injection and Abort Systems, T. Mori,MAC2014

29

Injection Kicker magnet(Total 12 thyratrons are used ) KEKB continuous injection (5〜10Hz)> SKEKB 25Hz injection KEKB: life time of thyratron (CX1154C) ->3 years-SuperKEKB : life time of thyratron : 1 year?
three possibilities(1) Use long life thyratron (CX1826A)(2) Replace thyratron to semiconductor device(SI thyristor? or commercial available Solid State Thyratron
Replacement ? )(3) Standard Thyristors + Saturable inductance(Pulse compresscircuit) 5μsec -> 1μsec
We chose (1) Long Life thyratron for HER (CX1826A has beenused for 6 years in KEKB)

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

MR ABORT

31

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Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

32

K. OideAbort optics with DC sextupole Instead of pulsed quadrupoles, a DC sextupole isused for enlarging the horizontal beam size.
 A DC sextupole is installed between the abort
kickers and the abort window. The deflectedbeam feels an additional quadrupole kickeffectively.
 Another DC sextupole is needed to make a pairof sextupoles for cancellation of the geometricalnonlinearity.
The pair of Sextupoles is connected by I or - Itransformation.

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Abort system of KEKB

33

Abort fail-safe system
DCCT detects current
Weak bend shut down
Beam scatters all aroundK. Satoh•••

Horizontal abort kickers kick the stored beam out of vacuum chamber (Rise time〜500ns)
Beam is extracted through Ti window to the atmosphere before entering Lambertson magnet
Vertical kicker sweeps beam vertically: energy deposit on Ti window is diffused
The beam is bent downward by Lambertson and leads to Dump

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Mar. 4, 2014

Abort system of SuperKEKB

KEKB

SuperKEKB

Horizontal kicker：
fast kick to abort window
Vertical kicker：
slow sweep vertically•Beam profile on abort window

Vert. kick±𝜎𝑥Powerdensity
maximum
atturning
points !!

Low emittance beam has higher possibility of destroying
abort window than KEKB beam
Enlarging horizontal beam size required additionallyLER

HER

Horizontal kicker：
fast kick to the Abort window
Vertical kicker：
slow sweep vertically
PULSED quadrupole：enlarge the horizontal beam size

Horizontal kicker：
fast kick to the Abort window
Vertical kicker：
slow sweep vertically
DC sextupole：enlarge the horizontal beam size

Abort fail-safe system like KEK is also designed
Schematic view of new beam profile on abort window±𝜎𝑥

6μm shift

Vert. kickVertical kicker•

34

T. Mimashi

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201435

Abort Beam Optics with Betatron Injection
herfqlc5605_AbortSext_BI_20121128a2_Extracted.deck

HER

N. Iida𝑒 − Beam

Beam dump
Abort window
Abort kickers
Abort sextupoleMar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201436

HER Optics for Betatron Injection/users/iida/sad/skekb/injection/her/herfqlc5605_AbortSext_20120316a2.deck

Matching：
βx1=βx2βy1=βy2νx1-νx2=1.5
νy1-νy2=1.0
AbortSext(1)AbortSext(2)1: AbortSext(1)2: AbortSext(2)ηx=0
at the center𝑒 − Beam of the sexts.

Injection point

Abort region

εx=4.511nm
εy=11.28pm
Emittance change
is negligible.

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201437

Dynamic aperture
Case1:K2=0 (W/o sextupoles)𝜏 = 610 s

Dynamic apertures & Touschek lifetimes are tested
with insertion of a pair of sextupoles.
The life time is optimized for each sextupoles.
Case1: SEXT FSXAB1 =(L =.334 K2 =0 ) -> 610 sec Case2: SEXT FSXAB1 =(L=.334 K2 =2.777278350689298 ) -> 600 sec Case3: SEXT FSXAB1 =(L =.334 K2=4.52820764294694 ) -> 620 sec

Case2:K2=2.777

Case3:K2=4.528

𝜏 = 600 s

𝜏 = 620 s

No performance drop found.

Y. Ohnishi

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201438

Abort Beam Optics for Synchrotron injection
herfqlc5605_AbortSext_20121128a2_Extracted.deckHER

e- BeamBeam dump
Abort window
Abort kickers Abort sextupoleMar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201439

HER Optics for Synchrotron injection/users/iida/sad/skekb/injection/her/herfqlc5605_20111227_AbortSext_20120316a2.deck

AbortSext(1)AbortSext(2)e- BeamMatching：
βx1=βx2βy1=βy2νx1-νx2=1.5
νy1-νy2=1.0
1: AbortSext(1)2: AbortSext(2)ηx=0Abort region
Injection pointat the centerof the sexts.

εx=4.646nm
εy=11.62pm
Emittance changes
are negligible.

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Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

40

Protection from Coherent Oscillation
 Avoiding abort beams hit outside of abort window Vertical

Acceptance determined by vertical mask Coherent oscillation amplitudes:


LER: 4.7 × 10−8 m−8 HER: 3.8 × 10m


Amplitudes small enough: no protection applied Horizontal
Max. displacement at abort window calculated(orbit)+3.5𝜎𝑥 + 𝜂𝛿(1%)＋(coherent oscillation)
 HER：50mm
 LER：47.6mm


Coherent oscillation amplitudes
HER: 6.8 mm(6𝜎𝑥 ) LER: 6.8 mm(5𝜎𝑥 )

5 or 6𝜎𝑥 coherent oscillation amplitudes make interlock
BPM trigger abort signal

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Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

41

Protection from Coherent Oscillation

Abort beam may hit outside of abort window
Vertical oscillation
Vertical acceptance determined by vertical mask
 Vertical amplitudes:


LER: 4.7 × 10−8 m−8 HER: 3.8 × 10m


Amplitudes small enough: no protection

Horizontal oscillation(orbit)+3.5𝜎𝑥 + 𝜂𝛿(1%)＋(coherent oscillation)
 Max. amplitudes at abort window

HER：50mm


LER：47.6mm
Synchrotron入射：Coherent振動＝6.8mm＝5.7σx
Betatron入射：Coherent振動＝6.8mm＝6.2σx
Coherent振動＝6.5mm＝5.4σx

Coherent oscillation amplitudes
HER: 6.8 mm(6𝜎𝑥 ) LER: 6.5 mm(5𝜎𝑥 )

5 − 6𝜎𝑥 coherent oscillation amplitudes trigger abort signal

Power Supply
 Issues Pulse compress circuit

We could get enough rise time (< 200nsec), but 10μsec
flatness is not enough.



Add dummy inductance to the coil

Flatness is improved from 14.6% -> 8.8% (or better)Power Supply 3

Operation Current(Horizontal kicker)

LERHER

1.4kA (4GeV)
1.46kA(4.16GeV)

1.26kA (7GeV)
1.55kA (8.6GeV)

Maximum currentof Power supply

1.7kA

Current drop

8.8%

# of kicker magnets

Horizontal 1
Vertical 1
Pulsed quad 2

Horizontal 4
Vertical 1

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

Output Current of Power Supply
Inductance 4.5μH/165Ω+940pF
Voltage 39.3kV(W/ additional inductance)(500A/div,500ns/div)
Peak 1750Ap(103%)
Flat 1700A(100%)
Rise time (2%-90%) 150ns
 Sufficient

Whole pulse(500A/div,5μs/div)
10μs 8.8% Drop44

Output Current(500A/div,500ns/div)
Peak 2250Ap(110%)
Flat 2050A(100%)
Rise Time(2%-90%) 150ns

Inductance 2.2μH//165Ω+940pF
Voltage 37.0kV

Whole Pulse(500A/div,5μs/div)
10μs Drop 14.6%

Mar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

DR INJECTION/EXTRACTION

46

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Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC2014

47

Kickers for DR Injection/Extraction
 Power supply study on going Both rising & falling times should be fast for otherbunchesMar. 4, 2014

Development of Pulse Magnets for Injection and Abort Systems, T. Mori, MAC201448