Enhancing positron production using front surface target structures

We report a target design which produced substantial gain in relativistic electron-positron pair production using high-intensity lasers and targets with large-scale micro-structures on their surface. Comparing to an unstructured target, selected Si microwire array yielded near 100% increase the laser-to-positron conversion efficiency 10 MeV average emitted positron energy under nominally same experimental conditions. had established multi-scale particle-in-cell simulation scheme simulate both laser absorption subsequent productions thick metal target. The results are supported by simulations demonstrating performance is due higher of into electrons kinetic energies greater than enhanced direct acceleration enabled array.