7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Estimation of laser parameters for generating enough number of energetic
heavy ions for applying as the injector of the next generation heavy ion
synchrotron accelerator
M. Hata1, S. Kojima1, T. Miyatake1,2, T.-H. Dinh1, Ko. Kondo1, N. Hasegawa1, M. Ishino1, M. Mori1,H. Sakaki1, M. Nishiuchi1, A. Kon1, M. Nishikino1, M. Kando1, T. Shirai3, and K. Kondo1
1
Kansai Institute for Photon Science (KPSI), National Institutes for Quantum Science andTechnology (QST), 2 Interdisciplinary graduate school of engineering sciences, Kyushu University,
Institute for quantum medical science (IQMS), 3 National Institutes for Quantum Science andTechnology (QST)e-mail (speaker): hata.masayasu@qst.go.jp
The National Institutes for Quantum Science andTechnology (QST) is currently conducting the quantum
scalpel project, which aims to improve the performanceand miniaturization of heavy ion cancer therapy devices,which are highly effective in treatment [1,2]. The“Quantum scalpel” means cancer therapy using aquantum beam without a real scalpel in a body. It’s atreatment method with minimal side effects, making it
possible for patients to go to the hospital (day surgery)and be treated for cancer while working. The fifth
generation of heavy ion cancer therapy devices, namely
the Quantum Scalpel consists of the laser ion injector,
super-conducting synchrotron, and super-conducting
rotating gantry as shown in Figure 1. It is required tominiaturize the ion injector and synchrotron to develop
compact heavy ion cancer therapy devices. In thequantum scalpel project, the synchrotron and injector
will be miniaturized by introducing super-conductingtechnology and replacing the conventional linear
accelerator with the laser ion injector, respectively. Laser
ion acceleration has a large acceleration gradient and its
technique is expected to develop a compact ion injector[3].
The requirement for the injector of the quantum scalpel
is the 10 Hz generation of more than 108 of 4 MeV/u
C6+ ions with 1% energy bandwidth. However, at thepoint of the laser acceleration, the 10% energy

bandwidth of these ions is allowable. The 10% energy
bandwidth of these carbon ions is compressed to 1%
using the phase rotation technique after the laser
acceleration and then they are transported to thesynchrotron.
We have conducted quasi-1D and 2D PIC simulations
including collisional and ionization processes to verify
the condition of C6+ generation. These simulation results
agree with the simple model that roughly predicts themaximum sheath strength and achievable ionization
degree. These simulations show the collisional effects on
C6+ acceleration. In addition, we have also conducted
3D pure PIC simulations to evaluate C6+ ion energy
spectra quantitatively. Finally, considering the results of2D PIC simulations including collisional and ionization
processes and pure 3D PIC simulations, we havediscussed the laser condition to generate 108 of 4MeV/u
C6+ ions with 10% energy bandwidth.
[1] K. Noda, “Progress of radiotherapy technology withHIMAC,” J. Phys.: Conf. Ser. 1154, 012019 (2019).
[2] H. Ishikawa et al., “Carbon-ion radiotherapy forurological cancers,” Int. J. Uro. 29, 1109–1119 (2022).
[3] M. Nishiuchi et al., “Dynamics of laser-driven
heavy-ion acceleration clarified by ion charge states”,
Phys. Rev. Res. 2, 033081 (2020).

Figure 1. Quantum scalpel system (a fifth generation compact and high-performance heavy ion radiotherapy system). It
consists of a laser ion injector, a superconducting synchrotron, and a superconducting gantry, and measuresapproximately 20 meters by 10 meters.