a1 Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China (firstname.lastname@example.org)
a2 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China (email@example.com)
For high-energy gain of electron acceleration by a laser wakefield, a stable or guiding propagation of an ultrashort, high-intensity laser pulse in a gas-target plasma is of fundamental importance. Preliminary experiments were carried out for the propagation of 30-fs, ~100-TW laser pulses of intensities ~1019W/cm2 in plasma of densities ~1019/cm3. Self-guiding length of nearly 1.4 mm was observed in a gas jet and 15 mm in a hydrogen-filled capillary. Fluid-dynamics simulations are used to characterize the two types of gas targets. Particle-in-cell simulations indicate that in the plasma, after the pulse's evolution of self-focusing and over-focusing, the high-intensity pulse could be stably guided with a beam radius close to the plasma wavelength. At lower plasma densities, a preformed plasma channel of a parabolic density profile matched to the laser spot size would be efficient for guiding the pulse.
(Received November 20 2011)
(Revised April 23 2012)
(Accepted April 30 2012)
(Online publication May 28 2012)