A Spatial distribution of MeV ions in the interaction of intense laser pulses with cluster-gas targets

Kanasaki, Masato; Jinno, Satoshi   ; Sakaki, Hironao; Nishiuchi, Mamiko; Faenov, A. Ya.*; Pikuz, T.; Kondo, Kiminori; Oda, Keiji*; Yamauchi, Tomoya*; Matsui, Ryutaro*; Kishimoto, Yasuaki; Doria, D.*; Borghesi, M.*; Fukuda, Yuji

In laser-driven ion acceleration using cluster-gas targets, generated ions can be assigned to two components. One is a low energy component produced by Coulomb explosions of clusters. The other is a high energy component produced by a magnetic vortex acceleration mechanism. In the past studies, high energy ions were mainly measured by stacked CR-39 detectors to obtain the energy spectrum. In the present study, to reveal the acceleration mechanism, a spatial distribution of MeV ions was measured by CR-39 detectors which were encircled equidistant from the laser focus spot. The etch pit distribution on the CR-39 suggests that the acceleration mechanism cannot be explained only by Coulomb explosion mechanism, but by other complicated mechanisms.