beam commissioning of the kek digital accelerator · bm1 q1 bm3 (f) q2 (d)...
TRANSCRIPT
Beam Commissioningof the
KEK Digital Accelerator
• Digital Accelerator• KEK Digital Accelerator (KEK-DA)• ECR ion source and Einzel Lenz chopper• Injection Kicker• Beam Bunch Observation• Confine, Squeeze, Acceleration of the Beam• Summary
Taiki Iwashita (KEK)
HIF-HEDEP US-Japan Workshop @ Osaka Univ. Oct. 12~14, 2011
KEK-DA Collaborators
• KEK ※T. Iwashita, T. Adachi, T. Arai, D. Arakawa, K. Okamura, E. Kadokura, M. Kawai, T. Kawakubo, T. Kubo, K. Koyama, H. Someya, A. Takagi, K. Takayama, H. Nakanishi, M. Hashimoto, M. Wake
• Sokendai (Graduate University for Advanced Studies) Leo Kwee Wah
• Nagaoka University of Technology W. Jiang
• Nippon Advanced Technology K. Okazaki
• Pulse Power Japan Laboratory A. Tokuchi
Induction Cell(Transformer)
V
SwitchingPowerSupply
Digital Accelerator (DA)
Time
Confinement Voltage
Acceleration Voltage
Ion Bunch
SW2SW1
SW3SW4
Timing C
ontrol Unit
• Proposed by Takayama & Kishiro (KEK) in 2000
• Proof of principle experiments at KEK 12GeV PS in 2006
• RF cavity of conventional synchrotron is replaced by induction cell (Transformer)
• Switching power supply using high power MOS-FET is free from the limitation of band width of RF cavities and amps
• DA can accelerate all species of Ions without large injector → wide field of applications are expected
• Gate trigger signal is generated from bunch monitor signal
• Acceleration / Confinement are separeted function → Increase freedom of beam handling
IonBunch
BunchMonitor
KEK Digital Accelerator
4
B3
T. Iwashita et al., “KEK Digital Accelerator” Phys. Rev. ST-AB 14, 071301 (2011).
Induction cell
ECRIS & HVT
LEBT
HEBTExperiment AreaBeam Dump
ECRIS
Z0(120)V0
Z R CL
Induction cell
V3
Switching power supply
C0
Trasmission line(40m long)
(matching resister)
DCPowerSupply
CT
Induction Acceleration Hardware Overview
Primary loop
Finemet (nano‐structurecrystalline, Hitachi Metal)
Proton beam
Stacked induction cells(output:2 kV/cell)
2.5kV, 20A, 1MHz, 500nsec
Switching arm S1(7 MOSFETs in series)
Development by KEK・Nichicon
MOSFET board
Cupper heat sink
Cooling water
MOSFET(rear)
Gate driver IC(rear)
Gate triggerlight signal
DC‐DC converter for Gate drive power
5
Gas Feeder
Hexapole Magnet
Horn Antenna
Extraction Electrode
Mirror Magnet
Ceramic Insulatorfor pre-acceleration (14kV)
ECR Ion Source and High Voltage Terminal
• Permanent Magnet ECRIS installed inside 200kV High Voltage Terminal• He1+ is provided for acceleration experiment• C, N, O, etc can be available by changing gas
200kV High Voltage Terminal
Einzel Lenz
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.0
Ion
Beam
Cur
rent
, Ib[A
]
Micowave Power, Pin[W]
A
Microwave Power [W]
Ion Current
0.100sccm0.150sccm0.175sccm0.200sccm0.225sccm0.250sccm0.275sccm
Einzel Lenz Chopper
Control beam width by changing voltage of center electrode of Einzel Lenz
• Chop 5msec width beam from ECRIS make 5sec beam requested by acceleration scheme
Magnets
Magnets
Microwave (9.3GHz)
Gas (He, Ne, Ar)
Extraction Electrode
Einzel Lenz
+14kv 0 v
0 v 0 v
Plasma
ECRIS
5msec ion beam
5sec beam
Turn on/off Pulse HVby Solid StateMarx Generatorwith High power MOS-FET
T.Adachi et. al,. ‘‘A Solid-state Marx Generator driven Einzel lens Chopper’’, Review of Scientific Instruments 82, 083305 (2011)
Gate Open +11kVGate Close +17kV
EL chopper: Simulation / Experiments5mS He1+ Ion Beam
-2.00E-06
0.00E+00
2.00E-06
4.00E-06
6.00E-06
8.00E-06
1.00E-05
1.20E-05
-2.00E-03
-1.00E-03
0.00E+00
1.00E-03
2.00E-03
3.00E-03
4.00E-03
5.00E-03
6.00E-03
7.00E-03
8.00E-03
After TWT Amp Trigger (S)
Ifc (
A)
5μS Chopped Beam
0.00E+00
2.00E-06
4.00E-06
6.00E-06
8.00E-06
1.00E-05
1.20E-05
1.40E-05
1.60E-05
1.80E-05
5.00E-06 7.00E-06 9.00E-06 1.10E-05 1.30E-05
Ifc (
A)
0.4mS delay
1mS delay
3mS delay
7 8 9 10 11 12 13 14 15 16 17 180
2
4
6
8
10
12
14
Einzel Lens Voltage, V1/KV
Ion B
eam
Curr
ent, Ib/
μA
Ib Vs V1
IGUN Simulation:17kV of center electrode can stop 14keV beam
5sec width beam bunchTest bench results
5msec He1+ ion beam
[sec]
(Veridical)
Luminescent Plate+ CCD camera
Wire profile monitor(Horizontal)
BM2BM1
BM3Q1(F)
Q2(D)
Q3(F) Q4 (D) Q5(F) Q7(F)Q6(D)
Horizontal Vertical
βx
βy
Beam Profile measurement at beam transport line
EAnode (+)
InjectedBeam
s
x
Simulated phase space motioninside the field
x(m)
dx/ds
Electrostatic Injection Kicker
Anode (+) Ground
Vacuum Chamber
SubsidiaryElectrodes
SubsidiaryElectrodes
HV
(kV
)
Kicker voltage profile
Time (ms)
First Beam of KEK-DA
12s from Chopper trigger
5s
Bunch Monitor
Chopper Trigger2nd turn is stoppedby luminescent plate in the ring
Circulating Beam
15mV
1msec
Beam Confinement with Barrier Bucket(without acceleration)
Vbb on
Beam is alive 10 msec later from injection
Vbb offBeam decays at 10 msec later from injection
Medium Loss (1.4 ms)due to COD
Slow Loss (4 ms)due to Residual Gas Scattering
Loss by Residual Gas: neutralized &stripped & scattering
Fast Lossdue to Emittance Mismatch and Injection Error
Ion Beam Intensity
Neutralization (capturing e‐)
Being stripped, Losing e‐
Ion bunch
ion
Residual gas in vacuum
Charge‐state change
Beam Loss
Injection Optics
after
Time (sec)
Beam intensity (au)
Outside Intside
R1R2
R3 R4
ES Position Monitor
ZZZZZ
RRRRR ,
R+ = R2+R3, R- = R1+R4
Z+ = R1+R2, Z- = R3+R4
FFT analysis
Betatrontunes
Qx=2.19 (design 2.17)
Qy=2.30 (design 2.30)
After injection error correctionwith correctionwithout correction
Beam monitor
TOF calculationT(t)=L/V(t)
SetTimer T(t)
Amp. &Front EndProcessing
1MHz switching power supply
Waveshaping
BeamL
V(t)
DSP (Digital Signal Processor)
Optical Convertermodule
CCR(Central Control Room)
Induction Acceleration Cell
Optical fiber
Control System of induction Acceleration in KEK‐DA
PC for DSP control
USB
Beam timing pulse
NIM
Logic circuit
Matchingresistance
Oscilloscope for monitoring inductionoutput voltage
Signal divider(for alternativeOperation)
ECRIS Pulse chopper timing signal
R monitor Beam bunch signal
Timing pulse
Rsignal
Bunch Squeeze Experiment
time
time
Barrier Voltage
Beam Bunch
Injection
3.5msec
7msec
Barrier Voltage
DSP (Digital Signal Processor) changes timing ofBarrier Voltage by 8nsec/turn
(by T.Iwashita and T.Adachi)
ProjectedProjected
Squeezing in Mountain View & its projection
1st turn2nd turn3rd turn
Hundreds of turnAt injection
Stop squeezing at 7ms
Beam bunch
Simulated Phase Space Motion of Squeezing Experiment
tBarrier Voltage
bucket
Beam Density Profileat Injection
End of Squeezing
5s
1.5s
momentum spread=0.025% off-set=0.23%
ms s
Experiment Simulation
At injection
Cross point
final
t
t
t
1st turn
125th turn
820th turn
5 sec 5 sec1st turn
125th turn
820th turn
1st turn
820th turn
Comparison: Experiment VS. Simulation
estimated fromExperiment
Analog Devices
Beam monitor
300MHz
Amp. &Front EndProcessing
1MHz switching power supply
Beam
L
V(t)
FPGALess overhead,much compact than present DSP systemOptical
Convertermodule
CCR(Central Control Room)
Induction AccelerationCell
Optical fiber
Replace DSP by FPGA (Next Generation)
PC for FPGA control
JTAG
Beam timing Signal
Matchingresistance
Signal divider(for interm
ittentOperation)
ECRISChop timing signal
Xilinx Vertex5400MHz
ADC
Oscilloscope for Monitoring inductionoutput voltage
R monitor
Rsignal
Timing Signal
Beam bunch signal
Induction Acceleration In minimum B fields
max
max
2
max
2
Sweep distance in the horizontal direction:
(1)
where1.4 m
4 cmAllowed maximum momentum spread:
4 2.8 10140
Meanwhile,1
px D sp
D s
x
pp
p Ep E
20
2 402 3
2 30
6
4
(2)
where12
2 1 200 keV2 1.07 104 931 10 keV
4 931 0.2 10 keV
3.724 10 keV
1 0.8 keV0.8
1.07 10
acc
A m c Q e V
Q eVA mc
E A mc Q eV
E Q eV N turn Np Np
3
6
2
3
=2 10 (3)3.724 10
2.8 10 14 turn2 10
N
N
No acceleration voltage
with 0.8 kV acceleration voltage
13 turns
xmax
Ion Beam expected at KEK-DA
Species Z Q EnergyMeV/u
PPP PPS (10Hz)
He 4 2+ 88.0 2.1×1010 2.1×1011
O 16 6+ 50.4 7.0×1010 7.0×1011
Ne 20 6+ 32.6 7.0×1010 7.0×1011
Ar 40 8+ 14.6 5.3×109 5.3×1010
2010-2012 Bmax=0.84T, 10Hz operation、200kV injection
2012- (Magnet upgrade, install Laser Ablation Ion Source)
Bmax= 1.1T, 10Hz operation、200kV injection
Species Z Q EnergyMeV/u
PPP PPS (10Hz)
He 4 2+ 146.8 1.8×1010 1.8×1011
3He 3 2+ 248.5 1.75×1010 1.75×1011
C 12 6+ 146.8 5.8×109 5.8×1011
Ar 40 8+ 120.5 1.9×109 1.9×1010
Fe 56 26+ 127.8 1.3×109 1.3×1010
Au 197 79+ 96.8 4.4×108 4.4×109
Summary• KEK-DA started beam commissioning from June 2011• Fortunately damage from earthquake was very limited• 10~20A of He1+beam is provided from ECRIS• Barrier trapping, bunch squeezing, acceleration
experiments are going on
Next Plan• Accelerate & Extract Helium beam including He2+
• Accelerate N, O, Ne, Ar, etc.• Build a new application line
T. Iwashita et. al, "KEK digital accelerator"Physical Review Special Topics - Accelerators and Beams, July 2011 Vol.14, Issue 7
T.Adachi et. al,. ‘‘A Solid-state Marx Generator driven Einzel lens Chopper’’, Review of Scientific Instruments 82, 083305 (2011)