Recent Progress in X-Ray Laser Research in JAEA

Recent progress in x-ray laser (XRL) research in Japan Atomic Energy Agency (JAEA) is reviewed. The repetition-rate of the x-ray laser has been improved from each 20 minutes to 10 seconds (0.1 Hz) by installing new driver laser, TOPAZ, which allows us to promote the applications of fully spatial coherent 13.9 nm laser in the wide variety of research fields such as material science, single-shot x-ray holography and atomic physics. In order to improve the present performance of the x-ray lasers, we have investigated the possibilities of the enhancement of the peak brilliance using v-groove target and the generation of circularly polarized x-ray laser under a strong magnetic field. Towards shorter wavelength x-ray lasers, we have investigated several schemes. One is the use of reflection of the light by relativistic plasma mirror driven by laser-wake-field, and the other is photo-pumping scheme using K alpha emission from a solid target.