Present Status

1
Present Status of the Induction Synchrotron
Project
Ken Takayama and Superbunch G. High Energy
Accelerator Research Organization
(KEK) Contents Outline of the project Experimenta
l results in the KEK 12GeV PS All-ion accelerator
as an application Perspective Summary
RPIA2006, March 7th at KEK
2
Brief History of Induction Synchrotron Research
at KEK
Year Major topics Events
1999 Proposal of the Induction Synchrotron concept by Takayama and Kishiro nFACT99
2000 RD works on the 1MHz switching power supply started. EPAC2000
2001 RD works on the 2.5kV, 1MHz induction acceleration cell started. Proposal of Super-bunch Hadron Collider PAC2001 Snowmass2001
2002 ICFA-HB2002, FNAL EPAC2002,RPIA2002
2003 Project of 5M with 5 years term started using the KEK-PS. (Apr.) PAC2003 ICFA-HB2003, BNL
2004 The first engineering model of the switching P.S. was established. 3 induction acceleration cells (2kVx36kV) were installed. (May) First experimental demonstration of induction acceleration in the KEK-PS (Oct. - Nov.) Barrier trapping at the injection energy of 500MeV, a 500nsec-long bunch was achieved. (Dec.) APAC2004 EPAC2004 ICFA-HB2004, GSI CARE HHH2004
2005 Proposal of All-ion Accelerators Another 3 induction acceleration cells (2kVx36kV) were installed (Sept). Quasi-adiabatic non-focusing transition crossing was demonstrated in the hybrid synchrotron (RF capture induction acceleration), (Dec.) PAC2005
2006 Another 4 induction acceleration cells (2kVx48kV) were installed.(Jan.) First demonstration (Feb.) of the induction acceleration of a single bunch trapped in the barrier voltages the full demonstration of the IS concept RPIA2006
3
Exploratory Research Project (2003-2007) Experimen
tal Demonstration of Induction Synchrotron
Gate control system
Applications Proton driver Modification
of existing RF synchrotrons Super-bunch
Hadron Collider All-ion accelerator Hybrid
accelerator
Induction Acceleration System RD,
manufacturing Switching P.S. Ind. Cell
Super-bunch Acceleration in KEK 12GeV PS
Switching element RD
Beam Physics of Super-bunch
MOSFET SI-Thy SiC-MOSFET
in future collaboration and succeeding Projects
in collaboration with TIT, Nagaoka Tec. Univ. ,
JAEA, Nichicon, NGK, Sindengen, NAT
4
Funding Outline (fixed)
K
We are here.
Including the salary of Postdocs and full-time
engineering staff but does not include the
salary of KEK permanent staffs
5
Induction Synchrotron

• Separation of Acceleration and Confinement
• Acceleration system driven by a switching power
  supply

Induction acceleration cell for acceleration
Induction acceleration cell for confinement
Accelerator Ring
for proton and other ions
Proton or Ion bunch
Super-bunch
Vacc
Vbarrier
time
time
6
Difference between RF Synchrotron and Induction
Synchrotron seen in Phase-space
RF bunch
Super-bunch
DE
allowed maximum energy spread
Induction Synchrotron
RF Synchrotron
This space is not available for acceleration.
7
Possible scheme to generate induction
step-voltage for a barrier bucket and
super-bunch acceleration assuming the basic
flip-flop operation of an single unit
Specification of a cell element Symmetric
bipolar Vout 2 kV output t 300 nsec flat-top f
1 MHz
V
t
1
t
2
t
3
t
for super-bunch acceleration
3V
t
1
t
2
t
3
t
3t
t
Super-imposing in time
for barrier-bucket trapping
8
KEK 12GeV PS
Neutron/Muon Laboratry
Main Ring (C340m)
500MeV Booster
40MeV Linac
750keV Pre-injector
Experimental hall for fixed target experiments
9
Scenario of the POP Experiment
Induction acceleration system output voltage
2kV/set
Super-bunch Stacking Acceleration (500MeV -gt 8GeV)
Acceleration Induction (500MeV-gt8GeV) Confinement
RF with 3 sets
9-12 times injection
Super-bunch formation at 500MeV with 3/6 sets
Dilution in the phase space
A final goal is to modify the KEK PS (RF
synchrotron) to an Induction Synchrotron at the
last stage of its 30 years life.
10
KEK PS Accelerator Complex Induction
Accelerating System
Gate trigger generator observing station at CCR
Switching power supplies
12GeV PS MR C0340m
Induction cells (3 cells)
40MeV Linac
500MeV Booster
Induction Cavity
DC power supply
Matching resistances
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Switching Power Supplyswitching sequence, output
pulse
2.5kV, 20A, 1MHz, 500nsec
Details will be given by Tokuchi this afternoon.
V
S1
S3
1)
Gate pulse
dI/dt0
2)
S2
S4
Switching arm S1 (7 MOSFETs in series)
Output voltage
1)
2)
Key point pulse voltage can be generated at
timing and with pulse duration that you want, by
controlling a gate pulse of the MOSFETs.
12
Induction Acceleration Device consisted of 4
Cells(2kV/cell) and a single inner chamber
L110 mH R330 W C260 pF
Expedient parameters for cell driving
Outlet of coolant oil
-
Excitation Current flow
0.6 m
electric contact
Accelating Gap (ceramic)
1m
Nanocrystalline alloy (Finemet)
Inlet of coolant oil
13
Equivalent Circuit for Induction Accelerating
System
Switching P.S.
DC P.S.
Transmission line (40m long)
Induction Cell
V2
V1
C13
C11
R
C
V0
C0
L
Z0(120W)
V3
C12
C14
CT
Z
(matching resistance)
IZ (always monitored at CCR)
V0 V2
V3
ZIZ (calibrated)
14
Monitored signals of induction voltage and an RF
bunch signal in the step 1 experiment
1.6 kV/cell
1 (8Gev)-1.5(500MeV) msec

• Beam bunch signal was monitored at the 4th
  acceleration gap.
• Synchronization between two signals has been
  confirmed through
• an entire acceleration.

15
Machine Parameters (Step1) and Control/Monitoring
System
Beam Monitor (BM)
Circumference 339m Trans. energy gt
6.68 Inj./ext. energy 500MeV/8GeV Rev.
frequency 667-880 kHz Ramping time
1.9sec RF voltage 48 kV Harmonic
numb. 9 Induction voltage 4.8 kV
KEK PS
RF
IC
RF bunch
frf/h
FET-Gate Trigger-pattern Generator
Pulse Modulator
DSP Unit (Active Delay)
B(t)
Oscilloscope
1.9 sec
CCR
TC
Details will be given by Torikai on 3/8.
t
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Theoretical background to confirm induction
acceleration
Force balance in the radial direction
given by ramping pattern of bending field
Acceleration equation
Desired acceleration condition
Voltage received by bunch center
observable as a relative
position of an RF bunch to RF phase
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Experimental Facts Change in fs, Beam Intensity,
and B
Vrfsinf
fs
p-12.40
12.40
Vind(5.6kV) - Vind no Vind
p-5.70
5.70
f
-10
p10
0
p
TC
after transition
before Transition
6x1011ppb
8 GeV
500 MeV
K.Takayama et al., Phys. Rev. Lett. 94, 144801
(2005).
18
(No Transcript)
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Step 2 Confinement by Induction
Step-barriers Formation of a 600nsec-long bunch
t0msec after injection
injected proton bunch
6kV barrier-voltage
100nsec
t100msec after injection
Shallow notch potential
600nsec
trapped protons
Details will be given by Torikai in afternoon
session.
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RF On every 50 turns just after injection
150msec after injection every 1 turn
Mountain View
RF bucket Trapping
600nsec-long Super-bunch
just after injection every 50 turns
RF Off
Notch Potential Trapping
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Full Demonstration of the Induction Synchrotron
Concept from 500 MeV to 1.3 GeV (Step 3)
Vacc 7.2kV (1.8 kV x 4sets), Vbb 10.8 kV
(1.8kV x 6 sets)
N 8 x 1011/bunch Bunch length 400 nsec
without DR feedback
with DR feedback
Bunch signal
Bunch signal
signal
signal
Acceleration starts.
Acceleration starts.
Every RFs are turned off.
Details will be given by Torikai this afternoon.
22
Memorial Photo of a full demonstration of the
Induction Synchrotron Concept
February 27, 2006
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Focusing-free Transition Crossing (FFTC)
Dp/p
g lt gT

• Focusing voltage is turned off around
• Transition energy.
• Acceleration voltage is provided as
• a flat voltage.
• In RF Synchrotron (in hybrid scheme)
• RF voltage is turned off around
• Transition energy.
• Induction voltage is triggered for acceleration.
• In Induction Synchrotron
• Barrier voltage only is turned off around
• Transition energy.

f
Dp/p
drift
f
g gT
opposit drift
f
g gt gT
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Demonstration of Quasi-adiabatic Non-focusing
Transition Crossing
Shimosakis idea Linear change in RF amplitude
n1
Amplitude C never changed.
Amplitude of RF
(a) Dt and (b) DE size depend on n. (c) Bunch
length control by QNTC(n1). (sim)
Theory and experimental details will be by
Shimosaki on 3/9.
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Crucial Engineering Issues to realize the
Induction Synchrotron

• How does the acceleration follow the transient
  field ramping
• under a constant induced voltage?
• 
  
• -gt pulse-density
  control
• How is the beam centroid kept on the center of
• the vacuum chamber?
• DR feed-back -gt intelligent on-off control of
  the gate pulses
• combined with the
  beam position
• Details will be given by K. Torikai (KEK) on
  Wednesday.

26
Acceleration in the Induction Synchrotron Change
in an effective acceleration voltage by control
of the gate-pulse density (Patent)
Rapid cycle synchrotron
Slow cycle synchrotron
Resonant circuit power supply
Patterned power supply
B(t)
linear region
Bmax
dB/dt
2p/w
transient region
Bmin
dB/dt
t
t
Acceleration region
Acceleration region
Required accelerating voltage is almost constant
except the transient regions. This was
demonstrated in the KEK-PS
(Vacc)maxrC0w(Bmax-Bmin)/2
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Further RD Works
Next Generation of Switching Power Supply

• Switching power supply to drive a low impedance
• acceleration cell at 1MHz -gt novel
  solid-state switching elements
• talks by Jiang/Shimizu this afternoon
• and Nakahiro (Nagaoka T.U.) on Wendesday

Important Beam Physics Issues of the Induction
Synchrotron

• Over-focusing and defocusing due to the droop
  voltage
• Chaos-like diffusion caused by the discrete
  barrier voltages
• talk by Y. Shimosaki (KEK) on Wendesday

28
Motivation for All-ion Accelerators (AIA)
from the experimental demonstration of induction
acceleration in the KEK-PS

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

Allow to accelerate even quite slow particles
Betatron motion doesnt depend on ion mass and
charge state, once the magnetic guide fields are
fixed.
A single circular strong-focusing machine can
accelerate from proton to uranium.
Concept of an all-ion accelerator
almost injector-free for a low intensity
K.Takayama, K.Torikai, Y.Shimosaki, and
Y.Arakida, All Ion Accelerators, (Patent
2005-129387)
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Schematic View of AIA
Switching P.S.
DC P.S. (fixed V0)
Gate Controller
Bending and focusing magnet
Induction Acceleration cell
extraction
injection
Bunch monitor
High voltage Ion source
Beam lines
Details will be given on Friday and its typical
application is described in the poster session.
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KEK-PS operation schedule Road Map
2004
Calendar Year
2003
2005
2006
2007
2008
2009
Financial year
H16
H18
H15
H17
H19
PS
J-PARC
Test experiment ?
Slow-extraction
Booster
NML
Induction Sync. Project
Suceeding project

We are here.
(1) Induction acceleration
1.9sec 8GeV 1RF bunch
0.8sec 8GeV 1-2RF bunches
(2) Super-bunch formation
700 nsec-long beam at 500MeV
Handling exercise
(3) Super-bunch acceleration
1.9sec 8GeV 250nsec-long SB
Make scenario RD on Int. Standard Preparation of
Infra Experimetal demonstration
US-Japan Collaboration in RHIC and other rings
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Summary

• A reliable full module for the induction
  accelerating system consisting of
• 50kW DC P.S., Pulse Modulator,
  Transmission Cable, Matching Resistance,
• Induction Cell, which is capable of
  operating at 1 MHz, has been confirmed
• to run over 24 hours without any troubles.
• The digital gate control system with a function
  of beam feed-back has been developed.
• The induction acceleration of protons(6x1011ppb)
  in a circular
• accelerator ring has been observed, where
  a single RF bunch was accelerated
• from 500MeV to 8GeV (flat-top) with an
  energy gain of 4.8 kV/turn.
• A 600nsec-long proton bunch trapped in a shallow
  notch potential,
• which is generated with induction
  step-voltages, has been demonstrated.
• The quasi-adiabatic non-focusing transition
  crossing was demonstrated in the
• hybrid synchrotron (RF capture and
  Induction acceleration).
• A 400 nsec-long proton bunch captured in the
  barrier bucket was accelerated
• up to 1.3GeV with the induction
  acceleration voltage.
• This is a full demonstration of the
  Induction Synchrotron Concept.
• These results are crucial
  milestones to realize Super-bunch Hadron
  Colliders.
• and suggest that the acceleration in circular
  rings has entered into a new era
• with induction devices driven by
  a switching driver.

32
Appendix
33
Repetition dependence of the induced voltage
1 kHz
100 kHz
1 MHz
10 kHz
34
Microwave Instability observed in the KEK PS
ggt gT Phase Jump glt gT
Pulse shape just before TC
35
Microwave Instability comparison with simulations
Line density (simulation)
Phase space dist.
Line density (measurement)
Longitudinal Emittance
36
Possible Applications of Induction Synchrotron
Concept
energy region Application Relying characteristics Relying characteristics
energy region Application separated function arbitrary switching frequency
high energy E gt TeV Super-bunch Hadron Collider super-bunch MHz
medium energy 10 GeVlt E lt 1 TeV Proton Driver super-bunch MHz
low energy 1MeVlt E lt10GeV All-ion Accelerator from p to U Including Cluster-ion bunch combining kHz -gt MHz operation
37
????T010 msec (f0100kHz)
frf10 f0
??????T01 msec (f01MHz)
frf f0