Low-threshold ablation of dielectrics irradiated by picosecond soft X-ray laser pulses
ピコ秒X線レーザーパルスによる誘電体の低しきい値アブレーション
Faenov, A. Y.; Inogamov, N. A.*; Zhakhovskii, V. V.*; Khokhlov, V. A.*; 西原 功修*; 加藤 義章* ; 田中 桃子; Pikuz, T. A.*; 岸本 牧; 石野 雅彦; 錦野 将元; 中村 龍史; 福田 祐仁; Bulanov, S. V.; 河内 哲哉
Faenov, A. Y.; Inogamov, N. A.*; Zhakhovskii, V. V.*; Khokhlov, V. A.*; Nishihara, Katsunobu*; Kato, Yoshiaki*; Tanaka, Momoko; Pikuz, T. A.*; Kishimoto, Maki; Ishino, Masahiko; Nishikino, Masaharu; Nakamura, Tatsufumi; Fukuda, Yuji; Bulanov, S. V.; Kawachi, Tetsuya
Ablation of LiF crystal by soft X-ray laser pulses with wavelength 13.9 nm and duration 7 ps is studied experimentally and theoretically. It is found that a crater appears on a surface of LiF for XRL fluence, exceeding the ablation threshold 10.2 mJ/cm in one shot, or 5 mJ/cm in each of the three XRL shots. This is substantially below the ablation thresholds obtained with other lasers having longer pulse duration and/or longer wavelength. A new mechanism of thermomechanical ablation in large bandgap dielectrics is proposed. The theory explains the low ablation threshold via small attenuation depth, absence of light reflection, and electron heat conductivity.