Laser-driven ion acceleration by high intensity short-pulse high-contrast laser system at JAEA

Nishiuchi, Mamiko; Sakaki, Hironao; Nishio, Katsuhisa   ; Orlandi, R.  ; Sako, Hiroyuki   ; Pikuz, T.; Faenov, A. Ya.*; Esirkepov, T. Z.; Pirozhkov, A. S.; Matsukawa, Kenya*; Sagisaka, Akito; Ogura, Koichi; Kanasaki, Masato*; Kiriyama, Hiromitsu; Fukuda, Yuji; Koura, Hiroyuki   ; Kando, Masaki; Yamauchi, Tomoya*; Watanabe, Yukinobu*; Bulanov, S. V.; Kondo, Kiminori; Imai, Kenichi; Nagamiya, Shoji*

For the applications of compact injector, we conduct the ion acceleration experiments using relatively compact and high-contrast short pulse laser system, J-KAREN at KPSI JAEA. The on-target laser intensity of 10 Wcm with 200TW, less than 10J of energy, is achieved by controlling the temporal and spatial pulse profiles. Without applying plasma mirror system, the maximum proton energy of 43 MeV is obtained with aluminum (Al) 0.8 um thick target. In some shots we observe that the protons and Al ions are accelerated up to 30 MeV and 12 MeV/u, respectively. With the soft X-ray spectroscopy the Al ions are found to be almost fully stripped, which is caused by the synergy of three major effects: optical field ionization due to the laser and plasma collective fields; the electron impact ionization; and the X-ray single photon ionization. The observation of almost fully stripped Al ions proves that laser-driven ions acceleration is a promising ion source for the conventional accelerator. In addition, the observed energy of 12 MeV/u of the Al ions shows that the laser-based ion acceleration method can be the basis of a compact heavy ion injector for nuclear physics.