HIAT2015 - List of Authors (Takayama, K.)

Paper	Title	Page
MOPA16	Coherent Synchro-Beta Coupling in the KEK Digital Accelerator	77
	T. Monma, K. Takayama, T. Yoshimoto KEK, Ibaraki, Japan K. Takayama, T. Yoshimoto TIT, Yokohama, Japan K. Takayama Sokendai, Ibaraki, Japan
	The required acceleration voltage per turn in any circular accelerator is written by Vacc=ρC0dB/dt, where ρ, C0, and B are the bending radius, circumference of the orbit, and magnetic flux density, respectively. Since the guiding magnetic fields of the KEK Digital Accelerator, which is a fast cycling induction synchrotron, are excited sinusoidally, an ideal profile of Vacc is of half sine. From the engineering constraint of the current induction acceleration system, however, the output voltage is always constant between 1.5 kV and 2.0 kV. Thus the induction acceleration voltage pulse is discretely generated based on the specific pulse density program so as to satisfy a size of the required voltage integrated for a short time period. The induction acceleration cells are placed at the region where the magnitude of the momentum dispersion function is not zero but 1.4 m. It has been reported that the coherent motion of the beam centroid is strongly excited at the early stage of acceleration cycle . Discrete acceleration at the finite momentum dispersion function region is suspected to cause such a coherent motion. K.Takayama et al., "Induction acceleration of heavy ions in the KEK digital accelerator: Demonstration of a fast-cycling induction synchrotron", Phys. Rev. ST-AB 17, 010101(2014)
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MOPA17	Super-Bunch Induction Acceleration Scheme in the KEK Digital Accelerator	80
	T. Yoshimoto, K. Takayama TIT, Yokohama, Japan T. Adachi, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama KEK, Ibaraki, Japan T. Adachi, K. Takayama Sokendai, Ibaraki, Japan H. Kobayashi Tokyo City University, Tokyo, Japan X. Liu Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan
	One of our next missions for the KEK digital accelerator,* is to demonstrate super-bunch (very long beam) acceleration technique in which a beam length occupies over half of the ring at injection**. This machine uses an induction cell driven by a switching power supply (SPS) which can generate rectangular pulses with their timings precisely controlled by a field-programmable gate array (FPGA). A power supply for the SPS is planned to be upgraded from present DC setup to a time-varying type generating a beam-required acceleration voltage per turn. This suppresses an emittance blow-up longitudinally and allows the super-bunch acceleration stably. In this presentation, we discuss concrete super-bunch acceleration scheme with simulation results and its hardware developments. T. Iwashita et al, Phys. Rev. ST-AB 14, 071301 (2011). K. Takayama, T. Yoshimoto et al, Phys. Rev. ST-AB 17, 010101 (2014). * K. Takayama et al, Phys. Rev. Lett. 88, 144801 (2002).
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MOPA18	A Racetrack-Shape Fixed Field Induction Accelerator for Giant Cluster Ions	83
	K. Takayama, T. Adachi, K. Okamura, M. Wake KEK, Ibaraki, Japan Y. Iwata NIRS, Chiba-shi, Japan
	Funding: Grants-In-Aid for Scientific　Research　（B)（KAKENHI　No. 15H03589) A novel scheme for a racetrack-shape fixed field induction accelerator (RAFFIA) capable of accelerating extremely heavy cluster ions (giant cluster ions) * is described. The key feature of this scheme is rapid induction acceleration by localized induction cells. Triggering the induction voltages provided by the signals from the circulating bunch allows repeated acceleration of extremely heavy cluster ions. Under the hypothesis that the RAFFIA is an induction synchrotron ** with an adiabatically varying circumference, the given RAFFIA example is capable of realizing the integrated acceleration voltage of 50 MV per acceleration cycle for C-60 (A=720 and Q=7). Using 90° bending magnets with a reversed field strip and field gradient is crucial for assuring orbit stability in the RAFFIA. Interesting beam physics such as resonance crossing during an acceleration cycle is discussed, including the structural stability of the cluster ion itself in the bending fields. * K.Takayama, T.Adachi, M.Wake, and K.Okamura, Phys. Rev. ST-AB 18, 050101(2015). ** K.Takayama and R.J. Briggs, Chapter 11 and 12 in Induction Synchrotron (Springer, Heidelberg, 2011).
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MOPA22	Beam Confinement Dynmics in a Barrier Bucket	92
	M. Hirose Tokyo City University, Tokyo, Japan X. Liu, K. Takayama, T. Yoshimoto TIT, Yokohama, Japan X. Liu, K. Takayama, T. Yoshimoto KEK, Ibaraki, Japan K. Takayama Sokendai, Ibaraki, Japan
	Barrier bucket beam trapping has some history. For the first time Griffin proposed this method and demonstrated in Tevatron project in 1983. There the barrier voltage has been generated in the way that higher harmonic components of RF voltage are superimposed. Since then several groups tried this method and it has been utilized in a routine operation of Fermilab Antiproton Recycler . The induction synchrotron concept was proposed in 2000. Barrier bucket created by the pulse voltages has been assumed for beam confinement in this accelerator. Its concept was confirmed in the experiment using the 12 GeV PS in 2006. From the early days of barrier bucket development chaotic-like motions of trapped particles in the phase space have attracted our concerns . However there are no systematic studies focusing on this point. The paper will discuss what causes such chaotic motions and how it is sensitive to barrier bucket parameters such as the voltage pulse profile with a finite rising/falling time and its amplitude. We will propose what counter measures are effective in order to mitigate increasing of the longitudinal emittance caused by this instability. J. Griffin et al., IEEE Trans. Nucl. Sci. NS-30, 3502, 21-23 Mar. 1983. ** Ken Takayamaet et al. , "Induction Synchrotron" (Springer, Heidelberg, 2011).
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WEPB19	Laser Ablation Ion Source for Highly Charge-State Ion Beams	234
	N. Munemoto Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan S. Takano, K. Takayama, I. Yamane KEK, Ibaraki, Japan K. Takayama TIT, Yokohama, Japan K. Takayama Sokendai, Ibaraki, Japan
	Acceleration experiments of gaseous heavy ions delivered from the ECR ion source are in progress in the KEK Digital Accelerator(KEK-DA).　KEK Laser ablation ion source (KEK-LAIS) has been developed to generate highly ionized metal ions and fully ionized carbon ions since 2012. Basic parameters such as a charge-state spectrum, momentum spectrum, spatial distribution of the plasma current, extracted ion beam current, and emittance have been obtained. Since diffusion of a laser ablated plasma is known to be controlled by magnetic guiding fields*, these parameters are measured as a function of solenoid guide fields and its length. Meanwhile, 10Hz continuous ablation plasma experiment, which is a crucial trial for accelerator applications, will be carried out with a newly developed moving target. The stability in accelerator beam parameters such as the pulse width and intensity is confirmed. At the conference, the extraction of heavy ion beams from the LAIS and post acceleration will be also discussed, including beam optics through the low energy beam transport line to the KEK-DA. K. Takayama et al., Phys. Rev. ST-AB 17 (2014) 010101. N.Munemoto et al., Rev. Sci. Inst. 85, 02B922 (2014). * M. Okamura et al., Rev. Sci. Inst. 81, 02A510 (2010).
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FRM1C03	A Compact Hadron Driver for Cancer Therapies with Continuous Energy Sweep Scanning	291
	K.W. Leo Malaysian Nuclear Agency, Kajang, Malaysia T. Adachi, T. Kawakubo, T. Monma, K. Takayama KEK, Ibaraki, Japan T. Adachi, K. Takayama Sokendai, Ibaraki, Japan T.S. Dixit SAMEER, Mumbai, India K. Takayama TIT, Yokohama, Japan
	A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is given. In order to realize a slow extraction technique in a fast cycling synchrotron, which allows the energy sweep beam scanning, the zero momentum-dispersion D(s) region and high flat D(s) region are necessary. The lattice has the two fold symmetry with a circumference of 52.8 m, 2 m-long dispersion-free straight section, and 3 m-long large flat dispersion straight section. Assuming a 1.5 T bending magnet, the ring can deliver heavy ions of 200 MeV/au at 20 Hz. A beam fraction is dropped from the barrier bucket at the desired timing and the increasing negative momentum deviation of this beam fraction becomes enough large for the fraction to fall in the ES septum extraction gap, which is placed at the large D(s) region. The programmed energy sweeping extraction makes spot scanning beam irradiation on a cancer area in depth possible without an energy degrader avoiding the production of secondary particles or the degradation of emittance. Details of the lattice parameters and computer simulations for slow extraction are discussed.
	Slides FRM1C03 [5.557 MB]
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Paper

Title

Page

Coherent Synchro-Beta Coupling in the KEK Digital Accelerator

77

T. Monma, K. Takayama, T. Yoshimoto
KEK, Ibaraki, Japan
K. Takayama, T. Yoshimoto
TIT, Yokohama, Japan
K. Takayama
Sokendai, Ibaraki, Japan

The required acceleration voltage per turn in any circular accelerator is written by Vacc=ρC0dB/dt, where ρ, C0, and B are the bending radius, circumference of the orbit, and magnetic flux density, respectively. Since the guiding magnetic fields of the KEK Digital Accelerator, which is a fast cycling induction synchrotron, are excited sinusoidally, an ideal profile of Vacc is of half sine. From the engineering constraint of the current induction acceleration system, however, the output voltage is always constant between 1.5 kV and 2.0 kV. Thus the induction acceleration voltage pulse is discretely generated based on the specific pulse density program so as to satisfy a size of the required voltage integrated for a short time period. The induction acceleration cells are placed at the region where the magnitude of the momentum dispersion function is not zero but 1.4 m. It has been reported that the coherent motion of the beam centroid is strongly excited at the early stage of acceleration cycle *. Discrete acceleration at the finite momentum dispersion function region is suspected to cause such a coherent motion.
* K.Takayama et al., "Induction acceleration of heavy ions in the KEK digital accelerator: Demonstration of a fast-cycling induction synchrotron", Phys. Rev. ST-AB 17, 010101(2014)

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MOPA17

Super-Bunch Induction Acceleration Scheme in the KEK Digital Accelerator

80

T. Yoshimoto, K. Takayama
TIT, Yokohama, Japan
T. Adachi, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama
KEK, Ibaraki, Japan
T. Adachi, K. Takayama
Sokendai, Ibaraki, Japan
H. Kobayashi
Tokyo City University, Tokyo, Japan
X. Liu
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan

One of our next missions for the KEK digital accelerator*,** is to demonstrate super-bunch (very long beam) acceleration technique in which a beam length occupies over half of the ring at injection***. This machine uses an induction cell driven by a switching power supply (SPS) which can generate rectangular pulses with their timings precisely controlled by a field-programmable gate array (FPGA). A power supply for the SPS is planned to be upgraded from present DC setup to a time-varying type generating a beam-required acceleration voltage per turn. This suppresses an emittance blow-up longitudinally and allows the super-bunch acceleration stably. In this presentation, we discuss concrete super-bunch acceleration scheme with simulation results and its hardware developments.
* T. Iwashita et al, Phys. Rev. ST-AB 14, 071301 (2011).
** K. Takayama, T. Yoshimoto et al, Phys. Rev. ST-AB 17, 010101 (2014).
*** K. Takayama et al, Phys. Rev. Lett. 88, 144801 (2002).

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MOPA18

A Racetrack-Shape Fixed Field Induction Accelerator for Giant Cluster Ions

83

K. Takayama, T. Adachi, K. Okamura, M. Wake
KEK, Ibaraki, Japan
Y. Iwata
NIRS, Chiba-shi, Japan

Funding: Grants-In-Aid for Scientific　Research　（B)（KAKENHI　No. 15H03589)
A novel scheme for a racetrack-shape fixed field induction accelerator (RAFFIA) capable of accelerating extremely heavy cluster ions (giant cluster ions) * is described. The key feature of this scheme is rapid induction acceleration by localized induction cells. Triggering the induction voltages provided by the signals from the circulating bunch allows repeated acceleration of extremely heavy cluster ions. Under the hypothesis that the RAFFIA is an induction synchrotron ** with an adiabatically varying circumference, the given RAFFIA example is capable of realizing the integrated acceleration voltage of 50 MV per acceleration cycle for C-60 (A=720 and Q=7). Using 90° bending magnets with a reversed field strip and field gradient is crucial for assuring orbit stability in the RAFFIA. Interesting beam physics such as resonance crossing during an acceleration cycle is discussed, including the structural stability of the cluster ion itself in the bending fields.
* K.Takayama, T.Adachi, M.Wake, and K.Okamura, Phys. Rev. ST-AB 18, 050101(2015).
** K.Takayama and R.J. Briggs, Chapter 11 and 12 in Induction Synchrotron (Springer, Heidelberg, 2011).

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MOPA22

Beam Confinement Dynmics in a Barrier Bucket

92

M. Hirose
Tokyo City University, Tokyo, Japan
X. Liu, K. Takayama, T. Yoshimoto
TIT, Yokohama, Japan
X. Liu, K. Takayama, T. Yoshimoto
KEK, Ibaraki, Japan
K. Takayama
Sokendai, Ibaraki, Japan

Barrier bucket beam trapping has some history. For the first time Griffin proposed this method and demonstrated in Tevatron project in 1983*. There the barrier voltage has been generated in the way that higher harmonic components of RF voltage are superimposed. Since then several groups tried this method and it has been utilized in a routine operation of Fermilab Antiproton Recycler . The induction synchrotron concept was proposed in 2000. Barrier bucket created by the pulse voltages has been assumed for beam confinement in this accelerator. Its concept was confirmed in the experiment using the 12 GeV PS in 2006**. From the early days of barrier bucket development chaotic-like motions of trapped particles in the phase space have attracted our concerns . However there are no systematic studies focusing on this point. The paper will discuss what causes such chaotic motions and how it is sensitive to barrier bucket parameters such as the voltage pulse profile with a finite rising/falling time and its amplitude. We will propose what counter measures are effective in order to mitigate increasing of the longitudinal emittance caused by this instability.
* J. Griffin et al., IEEE Trans. Nucl. Sci. NS-30, 3502, 21-23 Mar. 1983.
** Ken Takayamaet et al. , "Induction Synchrotron" (Springer, Heidelberg, 2011).

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WEPB19

Laser Ablation Ion Source for Highly Charge-State Ion Beams

234

N. Munemoto
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan
S. Takano, K. Takayama, I. Yamane
KEK, Ibaraki, Japan
K. Takayama
TIT, Yokohama, Japan
K. Takayama
Sokendai, Ibaraki, Japan

Acceleration experiments of gaseous heavy ions delivered from the ECR ion source are in progress in the KEK Digital Accelerator(KEK-DA)*.　KEK Laser ablation ion source (KEK-LAIS) has been developed to generate highly ionized metal ions and fully ionized carbon ions since 2012**. Basic parameters such as a charge-state spectrum, momentum spectrum, spatial distribution of the plasma current, extracted ion beam current, and emittance have been obtained. Since diffusion of a laser ablated plasma is known to be controlled by magnetic guiding fields***, these parameters are measured as a function of solenoid guide fields and its length. Meanwhile, 10Hz continuous ablation plasma experiment, which is a crucial trial for accelerator applications, will be carried out with a newly developed moving target. The stability in accelerator beam parameters such as the pulse width and intensity is confirmed. At the conference, the extraction of heavy ion beams from the LAIS and post acceleration will be also discussed, including beam optics through the low energy beam transport line to the KEK-DA.
* K. Takayama et al., Phys. Rev. ST-AB 17 (2014) 010101.
** N.Munemoto et al., Rev. Sci. Inst. 85, 02B922 (2014).
*** M. Okamura et al., Rev. Sci. Inst. 81, 02A510 (2010).

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FRM1C03

A Compact Hadron Driver for Cancer Therapies with Continuous Energy Sweep Scanning

291

K.W. Leo
Malaysian Nuclear Agency, Kajang, Malaysia
T. Adachi, T. Kawakubo, T. Monma, K. Takayama
KEK, Ibaraki, Japan
T. Adachi, K. Takayama
Sokendai, Ibaraki, Japan
T.S. Dixit
SAMEER, Mumbai, India
K. Takayama
TIT, Yokohama, Japan

A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is given. In order to realize a slow extraction technique in a fast cycling synchrotron, which allows the energy sweep beam scanning, the zero momentum-dispersion D(s) region and high flat D(s) region are necessary. The lattice has the two fold symmetry with a circumference of 52.8 m, 2 m-long dispersion-free straight section, and 3 m-long large flat dispersion straight section. Assuming a 1.5 T bending magnet, the ring can deliver heavy ions of 200 MeV/au at 20 Hz. A beam fraction is dropped from the barrier bucket at the desired timing and the increasing negative momentum deviation of this beam fraction becomes enough large for the fraction to fall in the ES septum extraction gap, which is placed at the large D(s) region. The programmed energy sweeping extraction makes spot scanning beam irradiation on a cancer area in depth possible without an energy degrader avoiding the production of secondary particles or the degradation of emittance. Details of the lattice parameters and computer simulations for slow extraction are discussed.

Slides FRM1C03 [5.557 MB]

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