Simulations of plasma channel formation by knife-like nanosecond laser beam

The results of the simulations performed in KIAM are presented. Formation of channels in gas targets using a ns-laser is considered in relevant regimes: output energy hundreds of Joules, nanosecond duration laser pulse, from 1 to 10 petawatt main laser pulse power. Such a kind of experiments are planned in the European laser center ELI-Beamline. They will develop a laser induced method of relativistic electrons acceleration, based on ideas investigated previously in NLBL. The magnetohydrodynamic codes NPINCH and MARPLE are used for 1D and 2D simulations of plasma channel formation in the region of elongated focus of knife-like nanosecond laser beam in under-critical gas density. Such plasma channel can be applied for transportation of high power femtosecond laser beams over large distances. The 2D simulations are performed to investigate the process of symmetrization of the channel, when the asymmetry of initial channel is caused by asymmetric deposition of the laser energy due to spatial structure of a plane focus of the laser beam. The simulations show how to reach the regimes of symmetric plasma channel formation. With 1D simulations the parameters of plasma channels for various cases under the condition of channel symmetrization are obtained.