Collimated GeV attosecond electron–positron bunches from a plasma channel driven by 10 PW lasers

摘要

High-energy positrons and bright γ-ray sources are of great importance both in fundamental research and for practical applications. However, collimated GeV electron–positron pair jets and γ-ray flashes are still rarely produced in the laboratory. Here, we demonstrate that by irradiating a near-critical-density plasma channel with two 10 PW-scale laser pulses, highly directional GeV electron–positron pairs and bright γ-ray beams can be efficiently generated. Three-dimensional particle-in-cell simulations show the formation of GeV positron jets with high density ( 8 × 10 21 / ?cm 3 ), attosecond duration (400 as), and a divergence angle of 14°. Additionally, ultrabright [ 2 × 10 25 ?photons? s ? 1 ?m m ? 2 ?mra d ? 2 ? ( 0.1 % ?bandwidth ) ? 1 ] collimated attosecond (370 as) γ-ray flashes with a laser energy conversion efficiency of 5.6% are emitted. These features show the significant advantage of using a plasma channel as compared with a uniform plasma and thus open up new possibilities for a wide variety of applications.