Source Development of Novel Coherent X-Rays and Their Applications in JAEA
This paper reviews recent progress in the source development of intense coherent x-rays and the applications in the research fields such as material science and laser processing in Japan Atomic Energy Agency (JAEA). In the source development, the polarization of the fully spatial coherent 13.9 nm soft x-ray laser (SXRL) in the transient collisional excitation (TCE) scheme was investigated experimentally. The result indicated that the SXRL beam was strongly polarized in the direction perpendicular to the target surface. In the alternative schemes toward the short wavelength region, intense higher-order harmonics with the photon energy of more than 300 eV was observed from a relativistic plasma generated with the laser intensity higher than 1018 W/cm2. In the applications of the 13.9 nm TCE laser, we observed temporal evolution of surface distortion of Pt sample pumped by a 80 fs optical pulse by use of x-ray laser interferometer using double Lloyd’s mirrors and reflectometer. In the study of SXRL ablation, the melting depth of the substances using single shot SXRL exposure was measured, and the result was quantitatively consistent with the calculated result based upon the spallative ablation model by molecular-dynamics code.
This work is partly supported by auspices of Japan Grant-in-Aid for Scientific research, Kiban (B), No. 25289244.