Japanese Program Overview

1
Japanese Program Overview

• Kazuhiko HORIOKA1, Mitsuo NAKAJIMA1,
• Masao OGAWA2, Yoshiyuki OGURI2, Jun HASEGAWA2,
• Takeshi KATAYAMA3,
• Shigeo KAWATA5, Takashi KIKUCHI4,5,
• Masakatsu MURAKAMI6, Katsunobu NISHIHARA6,
• Ken TAKAYAMA7
• Department of Energy Sciences, Tokyo Institute of
  Technology1
• Research Laboratory for Nuclear Reactors, Tokyo
  Institute of Technology2
• Center for Nuclear Science, The University of
  Tokyo3
• The Institute of Physical and Chemical Research,
  RIKEN4
• Department of Engineering, Utsunomiya University5
• Institute of Laser Engineering, Osaka University6
• Accelerator Research Organization, KEK 7

2
Outline

• Researches contributing HIF in Japan are
  reviewed.
• Ion Source Development (TIT, RIKEN)
• Repetitive induction Modulator and Induction
  Synchrotron
• (TIT, KEK, JAERI)
• kHz Induction Modulator and Accelerator System
  (TIT, KEK, RIKEN, UU)
• Beam Physics in Final Transport (TIT, RIKEN, UU)
• Chamber Physics (UU)
• Beam Plasma Interaction Experiments (TIT, RIKEN)
• Target Physics (ILE, UU)
• New Concept (ILE)
• TIT Tokyo Institute of Technology
• RIKEN The Institute of Physical and Chemical
  Research
• KEK High Energy Accelerator Organization
• JAERI Japan Atomic Energy Research Institute
• UU Utsunomiya University
• ILE Institute of Laser Engineering, Osaka
  University

3
High flux Ions are directly extracted from laser
ablation plasma at TIT
Direct ion extraction from drifting plasma Cu
Ions are extracted from 20mm gap Beam current
? Faraday Cup Beam emittance ? Pepper-pot image
4
With properly adjusting the operating condition,
high flux low emittance ion beam can be
extracted from ablation plasma
Beam Image
Beam Image
Can overcome the Bohm limit Matching problem is
overcome by controlling the ion supply close to
the space charge limitting current of effective
gap Beam bunch of Cu ions with 100mA/cm2 level
with emittance of 0.25pmmmrad and flat-top
waveform was obtained
Matching condition
5
Grid-controlled laser ion source can produce low
emittance long pulse beams
Grid-controlled ion source was operated at
over-dense mode with long pulse 20µsec at
10mA/cm2 level Virtual anode in the
grid-controlled gap works as a momentum filter
for the beam extraction
M.Yoshida, J.Hasegawa et.al., Jap. J Appl. Phys.,
Vol.42, p.5367 (2003)
6
Development of high-brightness laser ion source
at Tokyo Tech.
Anode aperture with fine mesh
Without grid control
With grid control
Over-dense
Stable extraction of ion beams from the laser ion
source was achieved using grid-control.
Source-limit
7
Concept of Induction Synchrotron
Principle
Image of Accelerator
RF Synchrotron
for confinement
Acceleration gap
RF voltage
Super-bunch
RF bunch
Combined function of accel./confinement
Voltage with gradient
Modulator Circuit
Pulse voltage
for acceleration
for confinement
Separate function
Induction Synchrotron
MHz operation -gt serious heat-deposit
K.Takayama and J.Kishiro, Induction
Synchrotron, Nucl. Inst. Meth. A451, 304(2000).
8
Operation Performance of Pulse-Modulator at KEK
(RD)
Output2.6kV?Rep-rate1MHz
Set-up for Induction Accelerating Module
Pulse Modulator
Trans. Cable
DC Power Supply
Vacuum duct
Pulse Modulator (Inner Structure)
Timemsec
0 1
2 3
4 5
Single period
by KEK Induction Synchrotron Project
9
Exploratory Research Project (2003-2007) Super-bun
ch Acceleration Experimental Demonstration of
Induction Synchrotron Project leader Ken
Takayama(KEK)
Laser-asist H- injection
Feed-back system Impedance management

• Applications
• Proton Driver
• Modification
• of existing RF
• Synchrotrons
• Super-bunch
• Hadron Collider

2000-2003
Induction Acceleration System RD,
manufacturing Power Modulator Cavity
Super-bunch Acceleration in KEK 12GeV PS
2003 - 2005
Switching element RD
MOSFET SI-Thy in low temp. SiC-MOSFET
2006 - 2010
Budget US 5M In collaboration with TIT,
JAERI and Japanese industries
10
Pulse modulator
Arrangement of Devices/Cables
12GeV Main Ring
Induction Accelerating Cavity
DC Power Supply
Booster
CW 1MHz 2kV/unit, 250nsec FT operation
11
Concept for Waveform Control
Typical Waveform of Module (4kV-100nsec-kHz)
Parallel Stacking (4kV-500nsec)
Module Structure Operational Range
100kV-kHz(FET-Driver) Waveform Stacking (Can
make Step, Rising, Sinusoidal Waveforms) Robust
against Load Condition
Series Stacking (20kV-100nsec)
Voltage Driver
12
Beam-plasma interaction experiments are running
in RIKEN-TITech collaboration.

• 10 keV-4 MeV/u, 1H - 92U projectilesare
  available at RIKEN and TITech.
• Measurement of -dE/dx and projectileeffective
  charge zeff in a laser-producedplasma target
• Energy (velocity)-dependence
• Projectile z-dependence

RIKEN
Narita
TITech
Tokyo bay
0
10
20 km
RIKEN
Projectile energy (MeV/u)
RIKEN 18-45 MHz frequency-variable linac (0.7-4
MeV/u)
TITech
TITech tandem (1.7 MV)
Projectile mass
13
Beam-plasma interaction experiments using a dense
z-pinch plasma at Tokyo Tech.
Large enhancement of energy losses of xenon ions
was observed under target plasma densities above
1019 cm-3, which was caused by an increase in
projectile effective charge due to some density
effects.
Energy loss of fully-stripped oxygen ions showed
good agreement with theoretical predictions.
14
Beam-plasma interaction experiments with dense
plasma targets are being planned at
RLNR/Tokyo-Tech.

• Experiments performed so far using Tokyo-Tech 1.7
  MV tandem accelerator

Enhanced -dE/dx in plasmas
Enhanced charge in plasmas
Plasma target ? Li H 2e-, ne ? 1018 cm-3,
kT ? 10 eV,
15
Energy loss of a single projectile in a
fully-ionized dense hydrogen plasma was
calculated by an MD method.

• Sophisticated numerical / theoretical researches
  have been so far published by several authors.
• A simple MD code was developed for rough
  estimation
• Target plasma confined in a test volume
• Coulomb forces between all particles
• Periodic boundary condition
• Equation of motion integrated by a leap-frog
  method

ZwicknagelPhys.Rep99, MaynardNIMB98 GerickeLP
B02, Boine-FrankenheimPhys. Plasma.96, ? ? ? ?
?
ne 1020 cm-3, kT 5 eV
? Ions(H) ? electrons
16
Lower temperature induces strong coupling,
leading to nonlinearity of the projectile
stopping.
PeterPRE91

• For low ne, high kT and high vproj, the results
  by LV(linearized Vlasov eq.), BE(binary
  encounter) and the MD calculation agree well each
  other.
• The nonlinear effect was estimated using a
  projectile-plasma coupling parameter g

ZwicknagelPhys.Rep99 GerickeLPB02
Temperature decreased
17
The projectile charge is partially screened by
the free electrons in the cold dense plasma
target.

• Distribution of plasma electrons during the
  passage of the projectile
• High electron densities aroundthe projectile are
  observed alsoin the z-vz phase space
• ? 10-20 electrons are closelyflying with the
  projectile.

20 keV/u, q 40, ne 1020 cm-3, kT 10 eV
30 keV/u, q 40, ne 1020 cm-3, kT 10 eV
Y.Oguri, Tuesday Morning, Tu.I.04
18
Final Beam Bunching (1)
Pellet
Research of Beam Dynamics during Final Beam
Bunching
Pb1 10GeV, Beam Current 400A?10kA
Buncher
Beam
Beam
Chamber
Transverse PIC Simulation with Initial KV Beam
T. Kikuchi, M.Nakajima, K.Horioka, T.Katayama,
Phys. Rev. ST-AB 7 (2004) 034201. T. Kikuchi,
M.Nakajima, K.Horioka, T.Katayama, J. Plasma
Fusion Res. 80 (2004) 87.
19
Final Beam Bunching (2)
Various Initial Beam Profiles
Waterbag Beam
Gaussian Beam
Particle Distribution -gt Uniform in
Real Space
Emittance Growth 515
20
Final Beam Bunching -gt Final Focus
Investigation of Beam Profile during Final
Focus Stage after Final Beam Bunching
Charge neutralization in Chamber is assumed.
at Focal Spot
Cross Section
Gaussian?
Flattop (semi-Gaussian)
21
Activities in HIF at Utsunomiya University (UU)
S.Kawata, T.Kikuchi,
T.Someya, A.I. Ogoyski / Final HIB transport /
HIB illumination on target / Implosion
Insulator Guide supplies electrons. Simple
neutralization method
S.Kawata, T.Someya, T.Nakamura, S.Miyazaki et.
al., Laser Particle Beams, Vol.21, pp.27-32
(2003)
22
/ Neutralized Ballistic FINAL BEAM TRANSPORT
Plasma Electrons neutralize HIB charge
/Neutralized beam dynamics at the middle in a
reactor chamber -gt may induce ambipolar
field HIB expansion at HIB surface lt-
Neutralizing hot electrons induces charge
separation at HIB surface -gt induces a
strong electric field in radial -gt extracts
HIB ions rdially gt 3-100keV (
4-10GeV )
23
Ambipolar field HIB expansion
lt- Neutralizing hot electrons induces charge

separation at HIB surface -gt induces a
strong electric field in radial -gt extracts
HIB ions rdially
Wednesday, 09 June Morning "Final Beam Transport
and Target Illumination"
24
Pulse Duration Dependence on Implosion
Study on tolerance of beam pulse duration for
implosion
Basic
Beam Profile
Longer
Larger Input Energy has Larger Tolerance in Beam
Pulse Duration Error for Fusion Output Energy.
Shorten
Power TW
Driver Energy 7MJ
Pulse Duration ns
Density Profile during Implosion by 2D Simulation
6MJ
5MJ
4MJ
Fusion Output GJ
3MJ
Pulse Duration ns
25
HIB Illumination 3-D Code is ready. by
Ogoyski, Someya, Kikuchi, Kawata 3-D HIB
illumination code is ready An Implosion code is
now under construction
Wednesday Afternoon, June 9, T. Someya, et al.,
HIB Illumination on a Target
T.Someya, A.I.Ogoyski, S.Kawata, T.Sasaki, Phys.
Rev. ST-AB, 044701 (2004)
26
M. Murakami (1)
Optimization of ICF Pellet Injection Utilizing
Precession (ILE)
mist accumulation
Rotating the pellet by electromagnetic means
could minimize the non-uniform mist accumulation
on the in-flight pellet surface. Under
perturbed inertial moment of the pellet, the
rotation undergoes precession, which results in
uniform mist accumulation on the spherical pellet
surface.
Without rotation
Semi-analytical study gives the optimum
conditions on the pellet injection and modal
behavior of the mist-accumulated-layer thickness.
With rotation
Primitive injection
Without precession
With precession
?
?
?
Modal thickness non-uniformity ()
?
?
1. Two key angles for injectiona ?
2. Pellet rotation with precession
achieves uniform mist accumulation.
3. Optimum injection angle a 90
degree, b 66 degree
27
Murakami (2)
A New Twist to IFE - Impact Ignition -
M. I - 14
A totally new ignition scheme is proposed, in
which the compressed DT main fuel is ignited by
impact collision of another fraction of
separately imploded DT fuel.
Isocontour map at a time shortly before the
impact
Isocontour map at peak comp- ression shortly
after the impact

• Advantages of Impact Ignition
• (1) Simple Physics
• (2) High Coupling Efficiency
• (3) High Robustness
• (4) High Gain
• (5) Low Cost

Basic experiments are now being conducted under
the operation of Gekko XII glass laser System at
ILE, Osaka, Japan.
ILE Osaka University
28
Summary

• Several Institutes and Universities are
  contributing HIF research in Japan
• High-Flux Ion Source Development (TIT, RIKEN)
• Repetitive induction Modulator was Developed
  (TIT, KEK, JAERI)
• kHz Induction Voltage Modulator is Under
  Development (TIT, KEK)
• Beam Physics in Final Transport (UU, TIT, RIKEN)
• Chamber Physics (UU)
• Beam Plasma Interaction Experiments are Extending
  to Dense Plasma (TIT, RIKEN)
• Target Physics (ILE, UU)
• New Concepts are Proposed for Fast Ignition,
  Neutralizing Method (ILE, UU, TIT,..)
• TIT Tokyo Institute of Technology
• RIKEN The Institute of Physical and Chemical
  Research
• KEK High Energy Accelerator Organization
• JAERI Japan Atomic Energy Research Institute
• UU Utsunomiya University
• ILE Institute of Laser Engineering, Osaka
  University