Simulation Study of Positron Beam Generation via Irradiating an Ultra-Intense Laser on a Hollow Target

摘要

By simulation with the relativistic PIC code EPOCH, it is found that a hollow target is more beneficial than a plane one for the collimation and compression of the positrons. Irradiating an ultra-intense laser (4 × 10~(23) W/cm~2) on a hollow target, 8:74 × 10~(15) positrons are generated. Due to the focusing effect of the transverse electric field formed in the hollow wall, the divergence angle is around 21?, while the maximum density of the beam is 4:77 × 10~(21) cm~(-3). When the laser intensity is doubled, both the yield (5:31 × 10~(16)) and the maximum density (1:57 × 10~(22) cm~(-3)) are greatly increased while the beam divergence gets even smaller (15:7?).