Experimental and theoretical studies on acceleration of background gas ions induced by Coulomb explosion of clusters

Fukuda, Yuji; Kanasaki, Masato; Jinno, Satoshi*   ; Sakaki, Hironao; Nishiuchi, Mamiko; Faenov, A.*; Pikuz, T.*; Kiriyama, Hiromitsu; Kando, Masaki; Kondo, Kiminori; Oda, Keiji*; Yamauchi, Tomoya*; Morishima, Kunihiro*; Watanabe, Yukinobu; Scullion, C.*; Smyth, A.*; Alonso, A.*; Doria, D.*; Borghesi, M.*; Matsui, Ryutaro; Kishimoto, Yasuaki

In this study, to understand the synergetic interplay between the Coulomb explosion of clusters and the background gas dynamics, we have conducted ion acceleration experiments using CO clusters embedded in background H gas with the J-KAREN laser at JAEA-KPSI. As a result, energy spectra for protons (from background gas) and carbon/oxygen ions (from clusters) are obtained separately for the first time. We found that the maximum energies of protons and carbon/oxygen ions are 1.5 MeV and 1.1 MeV/u, respectively. Based on the experimental results, the acceleration mechanism of background gas ions induced by Coulomb explosion of clusters is discussed with the help from numerical simulations which employ a particle-in-cell (PIC) method including relaxation and ionization processes of plasma particles (EPIC3D).