Induction acceleration of heavy ions in the KEK digital accelerator: Demonstration of a fast-cycling induction synchrotron

Phys. Rev. Accel. Beams

Wake

et al. 2019

Beam dynamics of the racetrack-shape fixed field induction accelerator for giant cluster ions were established. Linear optics theory and Runge-Kutta particle tracking approaches were developed, and the consistency between two approaches was confirmed. Use of gradient field bending magnets with a reverse field strip and ramping quadrupole doublets were crucial to achieve the orbit stability. A physically limited size of the huge bending magnet in the longitudinal direction generated the inherent closed-orbit distortion that substantially affected the orbit stability. In addition, the inherent field component B s along the orbit coordinate "s" induced horizontal-vertical (H-V) couplings. A possible correction method of this closedorbit distortion was proposed. A net effect of the H-V coupling was evaluated. Longitudinal motion with a time-varying transition energy, which is one of characteristic features in the racetrack-shape fixed field induction accelerator, was studied with the help of computer simulations.

Section: B Acceleration (Induction Device)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Beam dynamics of the racetrack-shape fixed field induction accelerator

Taufik

Phys. Rev. Accel. Beams

Wake

et al. 2019

“…The reference design does not employ a large-scale injector such as an RFQ or hadron linac, as well as the existing induction synchrotron [3]. The ion source is embedded in the 200-kV high-voltage platform (HVP).…”

Section: Lattice Design With Large Flat Dispersion Function Andmentioning

confidence: 99%

“…In this paper, a practical method to realize energy sweep extraction from a fast-cycling synchrotron is proposed. We assume a fast-cycling induction synchrotron [3]. A hadron bunch captured in the barrier bucket is continuously accelerated by the induction flat voltage, and a fraction of the beam bunch is spilled out from the stable barrier bucket by nonadiabatically changing the timing of the acceleration voltage controlling trigger signal in the desired time period.…”

Section: Introductionmentioning

confidence: 99%

Compact hadron driver for cancer therapies using continuous energy sweep scanning

Wah

Monma

Phys. Rev. Accel. Beams

et al. 2016

Self Cite

A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is presented. To realize a slow extraction technique in a fast-cycling synchrotron, which allows energy sweep beam scanning, a zero momentum-dispersion DðsÞ region and a high flat DðsÞ region are necessary. The proposed design meets both requirements. The lattice has two-fold symmetry with a circumference of 52.8 m, a 2-m dispersion-free straight section, and a 3-m-long large flat dispersion straight section. Assuming a 1.5-T bending magnet, the ring can deliver heavy ions (200 MeV=u) at 10 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 large enough for the fraction to fall in the electrostatic septum extraction gap, which is placed at the large DðsÞ region. The programmed energy sweep extraction enables scanning beam irradiation on a cancer site in depth without an energy degrader, avoiding the production of secondary particles and the degradation of emittance. Details of the lattice parameters and computer simulations for slow extraction are discussed. An example extraction scenario is presented. Qualities of the spilled beam such as emittance and momentum spread are discussed, as well as necessary functions and parameters required for the extraction system.

“…The concept of the induction synchrotron was demonstrated as a type of slow cycling synchrotron in 2006 [4]. Recently, a small-scale induction synchrotron, called the KEK digital accelerator, where heavy ions are directly injected into the ring from a 200 kV ion source, has been successfully used to accelerate heavy ions [5]. Ions in an induction synchrotron are accelerated and captured by pulse voltages generated by the 1-to-1 pulse transformers known as "induction acceleration cells" (ICs).…”

Section: Introductionmentioning

confidence: 99%

Racetrack-shape fixed field induction accelerator for giant cluster ions

Takayama

Phys. Rev. ST Accel. Beams

Wake

et al. 2015

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. The given RAFFIA example is capable of realizing the integrated acceleration voltage of 50 MV per acceleration cycle. Using 90°bending magnets with a reversed field strip and field gradient is crucial for assuring orbit stability in the RAFFIA.