ENHANCED LASER ION ACCELERATION BASED ON NEAR-CRITICAL DENSITY PLASMA LENS

When a laser pulse propagating in a near critical density plasma, its quality can be spontaneously improved by this “plasma lens” through transverse self-focusing, longitudinal profile steepening and pre-pulse cleaning. High energetic density electrons can also be generated in this process, which is crucial for the high gradient acceleration field formation. Both effect can significantly enhance the ion acceleration efficiency. Such near critical density plasma lens can be generated in front of the solid target using a proper controlled pre-pulse, which is normally considered “harmful” for the laser acceleration. A 3 mJ Ti-Sapphire laser system has been build at Peking University in order to experimentally study the pre-pulse effect on a solid target. The plasma lens will be used in the CLAPA at Peking University next year.