Ionization dynamics of cluster target irradiated by XFEL light

Nakamura, Tatsufumi; Fukuda, Yuji; Kishimoto, Yasuaki*

XFEL light has unique feature of high photon energy of 1220 keV and high flux of 10/pulse/cm. The irradiation of XFEL light onto Carbon clusters which model bio-molecules leads to generation of high energy electrons of 1220 keV via inner-shell ionization. These high energy electrons induces electric field of the order of TV/m at the surface and inside the target, which leads to field ionization. Depending on the laser intensity, this field ionization quickly ionizes all the outer shell electrons. By using PIC simulation code, which includes field ionization, collisional ionization, and Auger effect, we show how the target is ionized depending on laser intensity and target size.