LAUSR

A scheme to radiate a highly collimated γ-ray pulse is proposed through the interaction between an ultra-intense laser pulse and a narrow tube target. The γ-ray pulse, with high conversion efficiency, can be generated as a result of electron acceleration in a longitudinal electric field. In a Particle-in-Cell simulation with a 10-PW laser, 18% of the laser energy is transferred into the forward γ-rays in a divergence angle less than 3 ° . It is also found that such a highly collimated γ-ray pulse can be produced with a large range of tube diameters and laser intensities. This scheme could be realized in experiment with the coming 10-PW class lasers in the near future.