[en] In the laser-driven ion acceleration technology, the authors proposed a method for generating high-repetitive multi-MeV pure proton beams by utilizing Coulomb explosion of micron-sized hydrogen clusters. In this research, they developed a device for generating micron-sized hydrogen cluster targets by injecting high-pressure hydrogen gas cooled by a cryostat into a vacuum through a conical nozzle connected to a pulse valve. The size distribution of hydrogen clusters was estimated mathematically from the angular distribution of scattered light based on the Mie scattering theory using the Tikhonov regularization method. The maximum cluster size was estimated to be 2.15 ± 0.1 μm when hydrogen was injected at 25 K and 6 MPa. Then, a demonstration experiment of 0.1Hz high-repetitive proton acceleration targeting hydrogen clusters was conducted at the J-KAREN-P facility. In the energy measurement using a Thomson parabola spectrometer, pure proton beams with a maximum of 7 MeV were observed. The three-dimensional particle-in-cell (PIC) simulation of the interaction process between high power laser pulse and micron-sized hydrogen clusters suggested the highly directional quasi-monochromatic proton generation up to 300 MeV accelerated in the laser propagation direction. Therefore, this method has the potential to become a promising candidate in the future for a high-energy high-purity proton source with a high repetition rate. (A.O.)