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The KEK-All Ion Accelerator (KEK-AIA)

Tanuja Dixit

The Graduate University for Advanced Studies, SOKENDAIHigh Energy Accelerator Research Organization, KEK, JAPAN

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Contents• Introduction of Induction synchrotron

concept and its POP experiment• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in the AIA• New cell – 2 μsec long pulse cell• Gate control system • Summary

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Induction Synchrotron Concept

RF VoltageRF Bunch t

Voltage with gradient

Combined function

Acceleration/Confinement

Pulse voltage

For Acceleration

For Confinement

Separate function

t

t

Induction SynchrotronRF Synchrotron

Accelerator Ring

Induction cellfor acceleration

Induction cellfor confinement

Proton or Ion bunch

Vbarrier Vacctime time

Super-bunch

for proton and other ions

Difference between RF Synchrotron and Induction Synchrotron seen in Phase-space

ΔE

Induction SynchrotronRF Synchrotron

RF bunch Super-bunch

allowed maximumenergy spread

This space is not available for acceleration.

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Induction acceleration system and controls for POP

Cross-sectionof vacuum pipe

Induction Cell for Acceleration

Induction Cell for Confinement

KEK-PS

SwitchingPower Supply

Bunch Monitor

SwitchingPower Supply

DSP(1GHz)

DSP(720MHz)

Transmission line Transmission line

ΔR Monitor

Proton Beam

PatternController 1

PatternController 2

P2 Trigger Delay

Δp/p>0

S1S1

S2S2

S3S3

S4S4

dI/dtdI/dt=0=0

1)1)

2)2)

Gate pulseV

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Injection(500MeV)

Start of acceleration End of acceleration

(6GeV)

beam position (10 mm/div)

Beam current (1012/div) acceleration voltagepulse (1kV/div)

bunch signal K.Takayama et al., “Experimental Demonstration of theInduction Synchrotron”, Phys. Rev. Lett. 98, 054801 (2007)

P2 (just start of accel.) P2+400 msec near end of accel. (6GeV)

Movie of the POP experimentT.Dixit et.al. “ Adiabatic damping of bunch length in Induction Synchrotron” NIM-A 582 (2007)

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Contents• Introduction of Induction synchrotron

concept and its POP experiment• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in AIA• New cell – 2 μsec long pulse cell• Gate control system • Goal and time table

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from the Induction Synchrotron to All-ion Accelerators

Stable performance of the switching power supply from ~0Hz to 1MHzMaster trigger signal for the switching P.S. can be generated from a circulating beam signal

Allow to accelerate even quite slow particles

All-ion accelerators

A single circular strong-focusing machine can accelerate from proton to uranium,maybe including cluster ions.

from the experimental demonstration of induction acceleration in the KEK-PS

K.Takayama, K.Torikai, Y.Shimosaki, and Y.Arakida, “All Ion Accelerators”, (Patent 3896420, PCT/JP2006/308502), and J. of Appl. Phys. 101, 063304 (2007)

almost injector-freefor a low intensity beam

β 1

1 MHz

100 kHz

10 kHz

1 kHz

100 Hz

10 Hz

frf=f0

fswitch=f0

f0(revolution)=cβ/C

cβ

Synchronizationcondition

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Contents• Introduction of Induction synchrotron

concept and its POP experiment• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in AIA• New cell – 2 μsec long pulse cell• Gate control system • Summary

9

Monitor system

Low current bunch monitor

Low current ΔR monitor

Main Magnet/Orbit

Low field operationCOD correction

Source/ Injection groupECR ion source

200 keV beam lineElectrostatic kickerExtraction kicker

AIAAcceleration system

Acceleration scenarioNew cell

Gate control system

AIA Working Groups

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AIA using KEK PS-Booster

extraction kicker #1 - #3

injection bump & stripping foil

extraction kicker #4

extraction bump 1

extraction bump 2

low field extraction septum high field

extraction septum

LINAC Debuncher

RF

RF KEK 12GeV-PS 500 MeV Booster Rapid Cycle Synchrotron

40 MeV BTL

Booster Ring

beam monitors

two kickers

low field septum

Induction Cells

AIA Induction Synchrotron

Booster Ring Ion Source

Electric Kicker for injection

Induction Cells

"8" figure back-leg coils

Parameters Value

Magnetic flux, Bmin 0.02916 T

Magnetic flux, Bmax 0.8583 TFrequency of magnet ramping

10 Hz

Bending radius, ρ 3.3 m

Circumference, C0 37.71 m

Maximum acceleration voltage

3.24 kV

40Argon

E. Nakamura, Y.Arakida, T.Dixit, et.al, Proceedings of PAC07, Albuquerque, NM USA

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Booster Synchrotron –A Rapid cycle synchrotron

t

Bmax

2π/ω

Acceleration region

dB/dt

Acceleration voltage requirement always transient from 0 V to peak to 0 V

Solution - Pulse density control

0( )

acdB tV C

dtρ=

( ) cosacdc ac B

B t B B tω= −

Vac=3.24 kV (peak)

for 10 Hz operation

Near injection, revolution time is large therefore longer flat acceleration voltage pulse is required

3.02.52.01.51.00.50.0

kV

50403020100 msec

2

4

681

2MHz

Designed Acc. VoltageRevolution Frequency

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Pulse density control• Trigger based system – acceleration voltage

pulses can be controlled using trigger

Acceleration voltage requirement is dynamic ∝ dB/dt

Induction acceleration cells output is fixed

Pulse density control

Δt

t

ac cellV dt VΔ

=∫V

t

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Contents• Introduction of Induction synchrotron

concept and its POP experiment• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in AIA• New cell – 2 μsec long pulse cell• Gate control system • Summary

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Confinement voltage

ACCELERATION

SCHEME for AIA

Bunch

Acceleration voltage

Prerequisites

•4 usec injected bunch

•2.2 kV and 2 usec Acceleration voltage pulse

•1.8 kV and 250nsec confinement voltage pulse

4

3

2

1

0

kV

50403020100msec

Vac(des.)Vcell

III

IIIIV

15

4

3

2

1

0

kV

50403020100msec

Vac(des.)Vcell

III

IIIIV

Confinement voltage

ACCELERATION

SCHEME for AIA

Bunch

Acceleration voltage

16

4

3

2

1

0

kV

50403020100msec

Vac(des.)Vcell

III

IIIIV

Confinement voltage

ACCELERATION

SCHEME for AIA

Bunch

Acceleration voltage

17

4

3

2

1

0

kV

50403020100msec

Vac(des.)Vcell

III

IIIIV

Confinement voltage

ACCELERATION

SCHEME for AIA

Bunch

Acceleration voltage

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Simulation resultsNo. of particles – 10000 Initial beam Δp/p - ± 0.4% (assumption)

Momentum aperture - ± 1% Barrier voltage - 1.8 kVBeam survival & Energy gain Vs Time

100

80

60

40

20

0

Sur

viva

l %

50403020100time msec

60

40

20

0

Energy MeV/au

1.0

0.8

0.6

0.4

0.2

0.0

Nor

mal

ised

Em

ittan

ce

5040302010jitter in nsec

Normalised emittance vs jitter

100

80

60

40

20

0

Surv

ival

in %

50403020100jitter amplitude in nsec

Survival vs jitter amplitude

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Simulation results

Pulse density Vs Time

1.0

0.8

0.6

0.4

0.2

0.0

Puls

e de

nsity

1.00.80.60.40.2time msec

1.0

0.8

0.6

0.4

0.2

0.0

Puls

e de

nsity

2.01.81.61.41.21.0time msec

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Argon Ion Longitudinal phase space plots

-1.0

-0.5

0.5

1.0 dp/p %

-1000

0

1000

V

-4x10-6 -2 0 2 4sec

At injection

Blue- Barrier voltage pulse Green-Acceleration voltage pulse Red- Particles

-1.0

-0.5

0.5

1.0 dp/p %

-2000

-1000

0

1000

2000

V

-2x10-6 -1 0 1 2 sec

At 5.11 ms

-1.0

-0.5

0.5

1.0 dp/p %

-4000

-2000

0

2000

4000

V

-400x10-9 -200 0 200 400sec

At 20 ms

-1.0

-0.5

0.5

1.0dp/p %

-2000

0

2000

V

-150x10-9 -100 -50 0 50 100 150 sec

At 40 ms

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New requirement-

•Long acceleration voltage pulse

•Dynamic allocation of induction acceleration cells using DSP’s

Designed Acceleration voltage , Revolution Frequency Vs Time

3.02.52.01.51.00.50.0

kV

50403020100 msec

2

4

681

2MHz

Designed Acc. VoltageRevolution Frequency

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Contents

• Introduction of Induction synchrotron concept and its POP experiment

• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in AIA• New cell – 2 μsec long pulse cell• Gate control system • Summary

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Existing Induction acceleration cell

•Maximum rep-rate of 1 MHz

•Maximum output voltage of 2 kV with a droop of 15% in 250 ns

( ) exp where Z is total impedance (Cell + Matching resistance) L is Inductance of Cell

droop Zt L∝ −

10

5

0

-5

-10

A

7.5x10-67.06.56.05.5 sec

V0 C0 Z0(120Ω)

Z

R C

L

Induction CellV1

Switching P.S.

C11

C12

C13

C14

Transmission line(60m long)

(210 Ω matching resistance)

CT

V2

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SPICE SIMULATION

V0 C0 Z0(120Ω)

Z

R C

L

Induction CellV1

Switching P.S.

C11

C12

C13

C14 CT

V2R11

R12

R13

R14

DC P.S.

Equivalent circuit

• Flatness due to multiple reflections

•Undershoot because of downstream circuit conditions

1000

800

600

400

200

0

-200

V

4x10-63210sec

SPICEMeas.

1 TURN to 2 TURN

Demerit -

Secondary voltage becomes HALF

Vs=Vp/2

1 turn cell

L=110 μH

C=260 pF

R=330 Ω

Rm=220 Ω

2 turn cell

L=440 μH

C=180 pF

R=1280 Ω

Rm=134 Ω

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Wire Measurement

-1500

-1000

-500

0

500

1000

1500

V

6x10-6420-2 sec

Serial trigger Math signal

-2000

0

2000

V

13x10-612111098sec

Parallel trigger Math signal

GND Stand

Insulation

Ch1 Ch2

OSC

Pb1

V+V-

Wire

Wire experiment setup for 3 cells (2 turn)

InsulationGND Stand

Insulation

Ch1 Ch2

OSC

Pb1

V+V-

Wire

Wire experiment setup for 3 cells (2 turn)

Insulation

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Contents• Introduction of Induction synchrotron

concept and its POP experiment• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in AIA• New cell – 2 μsec long pulse cell• Gate control system• Summary

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5 DSP’s needs to be synchronized for start and stop of generation of SET/RESET pulse of acceleration

DSP usage

DC power supply

DSP Optical trigger unit

Switching Power Supply

Power lineAcceleration cell

beam simulator

Gate control

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Contents• Introduction of Induction synchrotron concept and its POP experiment• Motivation for AIA• KEK-PS Booster modification for AIA• Acceleration scenario in AIA• New cell – 2 μsec long pulse cell• Gate control system • Summary

beamcommission

modification works•beam line

•replacement of RF by IAS

ECR ion source cluster ion source

Accelerator09082007Year

beamcommission

modification works•beam line

•replacement of RF by IAS

ECR ion source cluster ion source

Accelerator09082007Year

The KEK-All Ion Accelerator �(KEK-AIA)ContentsInduction Synchrotron Concept Induction acceleration system and controls for POP ContentsContentsAIA using KEK PS-BoosterPulse density controlContentsSimulation resultsSimulation resultsNew requirement-ContentsContentsDSP usage Contents