Ion accelerations via the interaction of intense lase pulses with cluster targets

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

In order to understand the synergetic interplay between the Coulomb explosion of clusters and the background gas dynamics, an energy spectrum of carbon/oxygen ions from the CO clusters and that of protons from the background hydrogen gas are measured separately at 110 W/cm with a careful analysis of etch pit structures on CR-39. The maximum energies of carbon/oxygen ions and protons are determined as 1.1 MeV/n and 1.6 MeV, respectively. Moreover, we present a development of submicron-size hydrogen cluster targets using a cryogenic conical nozzle and their characterization with the Mie scattering method. Above 10 W/cm, the anisotropic Coulomb explosion of submicron-size hydrogen clusters could produce directional proton beams with energies of several tens of MeV, quite advantageous to the future applications, since they are inherently impurity-free, high rep.rate, and robust.