Through an intimate collaboration, the AIST and the NIRS has succeeded in generating quasimonoenergetic electron beam of 7 MeV energy from a 0.5 mm-long plasma by irradiating a laser pulse of 2 TW for 50 fs to a plasma of electron density as high as 1020 cm－3, which is an order of magnitude higher than that for the previous experiments. An evidence to demonstrate electron being accelerated by plasma wave has been obtained by diagnosing the laser plasma interaction. While the generation of monoenergetic electron beam with a laser plasma accelerator has been regarded unavailable up to now, the success in this study will provide a great step toward the practical use of the laser plasma accelerator.
