The Role of collision ionization of K-shell ions in nonequilibrium plasmas produced by the action of super strong, ultrashort PW-class laser pulses on micron-scale argon clusters with intensity up to 5 10 W/cm

Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi   ; Ota, Masato*; Egashira, Shunsuke*; Sakai, Kentaro*; Minami, Takumi*; Abe, Yuki*; Tokiyasu, Atsushi*; Kori, Hideki*; Kuramitsu, Yasuhiro*; Sakawa, Yoichi*; Miyasaka, Yasuhiro*; Kondo, Kotaro*; Kon, Akira*; Sagisaka, Akito*; Ogura, Koichi*; Pirozhkov, A. S.*; Kando, Masaki*; Kiriyama, Hiromitsu*; Pikuz, T. A.*; Fukuda, Yuji*

It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be m.