Measurement of electron oscillation by a plasma wave and a laser pulse

Kotaki, Hideyuki; Hayashi, Yukio; Mori, Michiaki; Kando, Masaki; Koga, J. K.; Bulanov, S. V.

Laser wakefield acceleration is regarded as a basis for the next-generation of charged particle accelerators. In experiments, it has been demonstrated that LWFA is capable of generating electron bunches with a very short duration of the order of ten femto-seconds. The oscillation of the electron beam by the transverse wakefield and the electric field of the laser pulse generates X-rays. The X-rays will be an useful tool for measurement of the ultrafast phenomena. The experiments have been performed with a Ti:sapphire laser system. The laser pulses with 160 mJ energy are focused onto a 3-mm-diameter helium gas-jet. The pulse width of the laser pulse is 40 fs. We observe two types of the electron oscillation. One of the oscillation is due to the transverse plasma wake. The other is due to the electric field if the laser pulse. The electron beam oscillation should be generated ultra-short X-rays. The X-rays will be an useful tool for measurement of the ultrafast phenomena.