Guiding of 100 TW Relativistic Laser Pulses by 10 mm Plasma Channels

Koga, J. K.; Chen, L.-M.; Kotaki, Hideyuki; Nakajima, Kazuhisa; Bulanov, S. V.; Tajima, Toshiki; Gu, Y. Q.*; Peng, H. S.*; Hua, J. F.*; An, W. M.*; Tang, C. X.*; Lin, Y. Z.*

First experiments for electron acceleration with the laser-gas plasma interaction have been carried out with 30 fs, 100 TW relativistic Ti:Sapphier laser pulse into a long slit (1.2 10 mm) gas plasma. The 10 mm length plasma channel formed that was longer than 20 times the Rayleigh length. Plasma density was the key factor for this long channel stimulation under 100 TW laser pulse irradiation that was much higher than critical power for relativistic self-focusing. For the first time, channel characteristics such as laser bending, hosing and cavity formation were demonstrated experimentally. In case of long channel guiding, accelerated electron bunch was tightly collimated with low emmitance mm mrad and quasi-monoenergetic electron bunch ( 70 MeV) was obtained as well. Accelerated electron charge current with electron energy 1 MeV was 10 nC/shot which was highest value in laser accelerator, to our knowledge, and ascribed to the contribution of long plasma channel. These well controlled laser-driven acceleration is an important cornerstone of relativistic engineering.