Investigation of optical emissions from the surfaces interacting with soft X-ray laser pulses

Ishino, Masahiko; Hasegawa, Noboru; Nishikino, Masaharu; Pikuz, T.; Faenov, A.*; Yamagiwa, Mitsuru; Kawachi, Tetsuya

The soft X-ray laser (SXRL) pulses with the fluencies of 10-30 mJ/cm were irradiated on the LiF, Cu, and Al plate targets. On all irradiated target surfaces, the ablation holes were confirmed. However, the optical emissions from the surfaces during the pulse irradiations were not observed. The model calculation predicts that the absorbed energy of SXRL pulse for a surface modification creates low electron temperature of only 0.1-1 eV in a material. The fact investigated by our experimental results is consistent with the theoretical calculations.